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5 Environmental Economics and Environmental Policy Upon completing this chapter, you will be able to:

➤ Describe principles of economic theory and summarize their implications for the environment ➤ Compare the concepts of economic growth, economic health, and sustainability ➤ Explain the approaches of environmental economics and ecological economics ➤ Describe the aims of environmental policy and assess its societal context ➤ Discuss the history of U.S. environmental policy and identify major U.S. environmental laws ➤ Characterize the institutions involved with international environmental policy and describe how nations

handle transboundary issues ➤ Outline the environmental policy process and evaluate its effectiveness ➤ Discuss the role of science in the policy process ➤ Contrast the different approaches to environmental policy

Contaminated beach near Tijuana River mouth

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Pacific Ocean

Atlantic Ocean

UNITED STATES

SOUTH AMERICA

San Diego

CANADA

MEXICO

Tijuana

CE N T R A L C A S E S T U DY

San Diego and Tijuana: Pollution Problems and Policy Solutions

“Never doubt that a small group of thoughtful, committed citizens can change the world—indeed it is the only thing that ever has.”

—Anthropologist Margaret Mead

“It is the continuing policy of the Federal Government . . . to create and maintain conditions under which man and nature can exist in productive harmony and fulfill the social, economic,

and other requirements of present and future generations of Americans.” —National Environmental Policy Act

T he beaches south of San Diego boast some of the world’s best waves for surfing.

These days, however, most surfers avoid the temptation. For it is here that the heavily

polluted Tijuana River flows across the international border from Mexico and empties

into the Pacific Ocean, disgorging millions of gallons of untreated wastewater.

“When it rains, I call it the sewage tsunami,” says surfer and environmentalist Serge Dedina. “For 40 square miles, from Im- perial Beach to Coronado, there is a brown plume as far as the eye can see.”

Such incidents occur when heavy rains overwhelm the abili- ty of sewage treatment plants to process wastewater. San Diego’s coastal waters receive stormwa- ter runoff when rains wash pollutants into local rivers. Across the border in the Mexican city of Tijuana, the aging, leaky sewer system becomes clogged with de- bris, causing raw sewage to overflow into the streets and, eventually, into the Tijuana River.

Winding northwestward through the arid land- scape of northern Baja California, Mexico, the Tijuana River crosses the U.S. border south of San Diego (FIG- URE 5.1A). A river’s watershed consists of all the land from which water drains into the river, and the Tijuana River’s watershed covers 4,500 km2 (1,750 mi2) and is home to 2 million people of two nations. The Tijuana River watershed is a transboundary watershed (so named because it crosses a political boundary—in this case, an international border), with approximately 70% of its area in Mexico. On the Mexican side of the bor- der, the river and its tributaries are lined with farms,

apartments, shanties, and facto- ries, as well as leaky sewage treat- ment plants and toxic dump sites. Rains wash pollutants from all these sources into the Tijuana Riv- er and eventually onto U.S. and Mexican beaches (FIGURE 5.1B).

Although pollution has flowed in the Tijuana River for decades, the problem grew worse in recent years as the re- gion’s population boomed, out-

stripping the capacity of sewage treatment facilities. As impacts intensified, people on both sides of the border pressed policymakers for action. As a result, Mexico and the United States worked together to construct a wastewater treatment plant to handle ex- cess waste from Tijuana. The South Bay International Wastewater Treatment Plant (IWTP) began operat- ing just north of the border in 1997 and treats up to 95 million L (25 million gal) of wastewater each day. Unfortunately, the facility reached its capacity with- in three years because Tijuana’s population grew so quickly, and excess wastewater began flowing downriver.

Since then, beach closures and pollution-related health advisories have been commonplace. Garbage carried by the river litters the beaches. “Every day I find broken glass, balloons, or can pop-tops. I’ve

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wastewater lowers concentrations of dissolved oxygen, killing economically valuable fish and shellfish. Pollution and beach closures reduce recreation and tourism both in Mexico and in southern California, whose beaches each year host 175 million visitors who spend over $1.5 billion. As a result, finding ways to reduce pollution will help the region economically.

Economics is the study of how people decide to use re- sources to provide goods and services in the face of demand for them. By this definition, environmental problems are also economic problems that vary with population and per capita resource consumption. Indeed, the word economics and the word ecology come from the same Greek root, oikos, mean- ing “household.” Economists traditionally have studied the household of human society, while ecologists study the broad- er household of all life.

Several types of economies exist An economy is a social system that converts resources into goods, material commodities manufactured for and bought by individuals and businesses; and services, work done for others as a form of business. The oldest type of economy is the subsistence economy. People in subsistence econo- mies meet their daily needs by subsisting on what they can gather from nature or produce on their own, rather than working for wages and then purchasing life’s necessities.

A second type of economy is the capitalist market econ- omy. In this system, interactions among buyers and sellers de- termine which goods and services are produced, how much is produced, and how these are produced and distributed. Capitalist economies contrast with state socialist economies, or centrally planned economies, in which government de- termines how to allocate resources. In reality, today’s capital- ist and socialist economies have borrowed much from one another and are in fact hybrid systems (often termed mixed economies).

In modern mixed economies, governments typically in- tervene in the market for several reasons: (1) to eliminate un- fair advantages held by single buyers or sellers; (2) to provide

even found hypodermic needles. It’s really sad,” one resident of Imperial Beach told her local newspaper.

Mexican residents of the Tijuana River watershed suffer more pollution because most live in poverty relative to their U.S. neighbors. Close to one-third of Tijuana’s homes are not connected to a sewer system, and in poor neighborhoods such as Loma Taurina, riv- er pollution directly affects people’s day-to-day lives by contaminating water for drinking and washing and by promoting risks of disease, especially when flood- ing occurs. The rise of U.S.-owned factories, or maqui- ladoras, on the Mexican side of the border also has contributed to pollution, through the direct disposal of industrial waste and by attracting thousands of new workers to the already crowded region. In many ways, economic inequities spanning the border region have aggravated its problems with water pollution.

As we explore environmental economics and en- vironmental policy in this chapter, we will periodically return to the Tijuana River watershed and see how people are making progress by using science and poli- cy to help address the region’s pollution challenges. ■

ECONOMICS: APPROACHES AND ENVIRONMENTAL IMPLICATIONS Many environmental problems share the mix of impacts we see in the Tijuana River watershed—harming human health, altering ecological systems, inf licting economic damage, and contributing to inequities among people. In the Tijuana River watershed, pollution affects the region’s economies—while economic inequities, in turn, worsen pollution. Sewage-taint- ed water carries pathogens (organisms that cause illness), pos- ing health risks and leading to higher medical costs. Untreated

U.S.

Tijuana River

Tijuana

San Diego

Tijuana River Watershed

Pacific Ocean

MEXICO

International Wastewater Treatment Plant

(a) Map of the Tijuana River watershed (b) Wastewater enters the ocean near Tijuana

FIGURE 5.1  The Tijuana River winds northwestward from Mexico into California just south of San Diego, draining 4,500 km2 (1,750 mi2) of land in its watershed (colored green in map) (a). Pollution entering the river affects people on both sides of the border and sometimes creates a visible brown plume of wastewater entering the Pacific Ocean (b). The photo shows an aerial view from the north, with Tijuana in the background.

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tragedy of the commons, p. 3–4). However, Scottish philoso- pher Adam Smith (1723–1790) believed that self-interested behavior could benefit society, as long as the behavior was constrained by the rule of law and private property rights and operated within fairly competitive markets. Known today as a founder of classical economics, Smith felt that when peo- ple are free to pursue their own economic self-interest in a competitive marketplace, the marketplace will behave as if guided by “an invisible hand” that leads their actions to ben- efit society as a whole. Smith’s philosophy remains a pillar of free-market thought today.

Neoclassical economics incorporates psychology and cost-benefit analysis Economists subsequently adopted more quantitative ap- proaches as they aimed to explain human behavior. Neoclassi- cal economics examines the psychological factors underlying consumer choices, explaining market prices in terms of con- sumer preferences for units of particular commodities. In neoclassical economic theory, buyers desire the lowest possi- ble price, whereas sellers desire the highest possible price. As a result of this conf lict, a compromise price is reached, and the “right” quantities of commodities are bought and sold. This balance is often phrased in terms of supply, the amount of a product offered for sale at a given price, and demand, the amount of a product people will buy at a given price if free to do so (FIGURE 5.3).

To evaluate an action or decision, neoclassical economists often use cost-benefit analysis. In this approach, economists total up estimated costs for a proposed action and compare these to the sum of benefits estimated to result from the ac- tion. If benefits exceed costs, the action should be pursued; if costs exceed benefits, it should not. Given a choice of alterna- tive actions, the one with the greatest excess of benefits over costs should be chosen.

This reasoning seems eminently logical, but problems often arise because not all costs and benefits can be easily identified, defined, or quantified. For example, it may be easy to tally up the costs of installing equipment to reduce pollution, yet difficult to assess the effects of pollution on people’s health or lifestyles. Moreover, monetary values can often be assigned more easily to economic benefits (such as jobs created by a factory) than to environmental costs (such as long-term health impacts of the factory’s pol- lution on a community), so economic benefits tend to be overrepresented in cost-benefit analyses. As a result, envi- ronmental advocates often feel these analyses are biased in favor of economic development and against environmental protection.

Neoclassical economics has profound implications for the environment Today’s capitalist market systems operate largely in accord with the principles of neoclassical economics. These systems have generated unprecedented material wealth for our socie- ties. Alas, four fundamental assumptions of neoclassical eco- nomics often contribute to environmental degradation.

social services, such as national defense, medical care, and education; (3) to provide “safety nets” for the elderly, victims of natural disasters, and so on; (4) to manage the commons (p. 3–4); and (5) to reduce pollution and other threats to health and quality of life.

Economies rely on goods and services from the environment Economies receive inputs (such as natural resources) from the environment, process them in complex ways that en- able human society to function, and then discharge outputs (such as waste) into the environment. Although these in- teractions between human economies and the nonhuman environment are readily apparent, traditional economic schools of thought have long overlooked the importance of these connections. Indeed, most mainstream economists still adhere to a worldview that largely ignores the envi- ronment (FIGURE 5.2A)—and this worldview continues to drive most policy decisions. However, modern economists belonging to the fast-growing fields of environmental eco- nomics and ecological economics (pp. 93–94) explicitly recognize that human economies are subsets of the envi- ronment and depend crucially upon it for natural resources and ecosystem services (FIGURE 5.2B).

Economic activity uses natural resources (pp. 2–3), the substances and forces we need to survive: the sun’s energy, the fresh water we drink, the trees that provide us lumber, the rocks that provide us metals, and the fossil fuels that power our machines. We can think of natural resources as “goods” produced by nature.

Environmental systems also naturally function in a man- ner that supports economies. Earth’s ecological systems purify air and water, form soil, cycle nutrients, regulate climate, pol- linate plants, and recycle the waste generated by our economic activity. Such essential processes, called ecosystem services (pp. 2, 36), support the life that makes our economic activity possible.

While our environment enables economic activity by providing ecosystem goods and services, economic activity can affect the environment in return. When we deplete natural resources and generate pollution, we often degrade the capac- ity of ecological systems to function. In fact, the Millennium Ecosystem Assessment (p. 16) concluded in 2005 that 15 of 24 ecosystem services its scientists surveyed globally were being degraded or used unsustainably. The degradation of ecosys- tem services can in turn disrupt economies, as we see along the Tijuana River, where pollution depresses people’s economic opportunities. Ecological degradation is harming poor people more than wealthy people, according to the Millennium Eco- system Assessment. As a result, restoring ecosystem services stands as a prime avenue for alleviating poverty.

Adam Smith proposed an “invisible hand” When economics began to develop as a discipline in the 18th century, many philosophers argued that individuals act- ing in their own self-interest would harm society (as in the

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Households

(a) Conventional view of economic activity

Payment for

products

Products (goods and

services)

Ecosystem services (e.g., recreation, pollination of crops, etc.)

Waste acceptance (ecosystem service)

Economy

Natural recycling: Climate regulation, air and water purification,

nutrient cycling, etc. (ecosystem services)

Natural resources (ecosystem goods)

Recycling

Labor

Agriculture, industry, business

Wages

Agriculture, industry, business

Households

(b) Economic activity as viewed by environmental and ecological economists

FIGURE 5.2  Standard neoclassical economics focuses on pro- cesses of production and consumption between households and businesses (a), viewing the environment only as a “factor of production” that helps enable the production of goods. In contrast, environmental economics and ecological economics each view the human economy as existing within the natural environment (b), receiving resources from it, discharging waste into it, and benefiting from various ecosystem services.

Are resources infinite or substitutable? One as- sumption is that natural resources and human resources (such as workers) are either infinite or largely substitutable and interchangeable. This implies that once we have used up a resource, we should be able to find a replacement for it. Cer- tainly it is true that many resources can be replaced. However, some cannot. Nonrenewable resources (such as fossil fuels)

can truly be depleted, and many renewable resources (such as forest products) can also be used up if we exploit them faster than they are replenished.

Should we discount the future? Second, neoclassical economics grants an event in the future less value than one in the present. In economic terminology, future effects are

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FIGURE 5.4  River pollution creates external costs. This woman washing clothes in the Tijuana River suffers pollution from factories upstream, and her use of detergents causes pollution for people living downstream.

By ignoring external costs, economies create a false im- pression of the consequences of particular choices and unjust- ly subject people to the impacts of transactions in which they did not participate. External costs comprise one reason gov- ernments develop environmental legislation and regulations.

Is all growth good? A fourth assumption of the neo- classical economic approach is that economic growth is re- quired to keep employment high and maintain social order. Economic growth, it is argued, should create opportunities for the poor to become wealthier. By making the overall eco- nomic pie larger, everyone’s slice becomes larger, even if some people still have much smaller slices than others. In today’s economies, economic growth has become the quantitative yardstick by which progress is measured.

To the extent that economic growth is a means to an end— a path to greater human well-being—it is a good thing. How- ever, when growth becomes an end in itself it may no longer be the best route toward well-being. Sociologists have even coined a word for the way material goods often fail to bring contentment to people affluent enough to afford them: afflu- enza. Moreover, critics of the growth paradigm fear that the endless pursuit of economic growth will eventually destroy our economic system, because resources to support growth are ul- timately limited.

How sustainable is economic growth? Our global economy is seven times the size it was just half a century ago. All measures of economic activity—trade, rates of production, amount and value of goods manufactured—are higher than ever before. This has brought many people much greater material wealth (although not equitably, and gaps be- tween rich and poor are wide and growing).

The modern-day United States exemplifies the view that “more and bigger” are always better. Spurred on by adver- tising and the increased availability of goods due to techno- logical advances and expanded global trade, Americans have embarked on a frenzy of consumption unparalleled in history.

“discounted.” Short-term costs and benefits are granted more importance than long-term costs and benefits, causing us to ignore the long-term consequences of policy decisions. Many environmental problems unfold gradually, and discounting causes us to downplay the impacts on future generations of the pollution we create and the resources we deplete today.

Are all costs and benefits internal? A third assump- tion of neoclassical economics is that all costs and ben- efits associated with an exchange of goods or services are borne by individuals engaging directly in the transaction. In other words, it is assumed that the costs and benefits are “internal” to the transaction, experienced by the buyer and seller alone. However, many transactions affect other members of society. For example, pollution from a maqui- ladora along the Tijuana River can harm people living downstream. In such a case, members of society not in- volved in producing the pollution end up paying its costs. When market prices do not take the social, environmental, or economic costs of pollution into account, then taxpay- ers bear the burden of paying them. Costs of a transaction that affect people other than the buyer or seller are known as external costs (FIGURE 5.4). External costs commonly include the following:

▶ Human health problems ▶ Property damage ▶ Declines in desirable features of the environment, such as

fewer fish in a stream ▶ Aesthetic damage, such as from air pollution or

clear-cutting ▶ Stress and anxiety experienced by people downstream or

downwind from a pollution source ▶ Declining real estate values resulting from these problems

Quantity

Market equilibrium

Demand

Supply

Pr ic

FIGURE 5.3  In a supply-and-demand graph, the demand curve indicates the quantity of a given good (or service) that consumers desire at each price, and the supply curve indicates the quantity produced at each price. The market automatically moves toward an equilibrium point at which supply equals demand.

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Can we conclude, then, that improvements in tech- nology will allow us to overcome all our environmental limitations and continue economic growth indefinitely? Surely we can innovate and achieve further efficiency and economic growth without depleting our resource base—but ultimately, nonrenewable resources are finite, and renewable resources can be exploited only at limited rates. If our pop- ulation and consumption continue to grow and we do not shift to full reuse and recycling, we will inevitably deplete resources and put ever-greater demands on our capacity to innovate.

Ecological economists argue that civilizations do not, in the long run, overcome their environmental limitations. Eco- logical economists apply principles of ecology and systems science (Chapter 2) to the analysis of economic systems, and they view natural systems as good models for making human economies sustainable. In nature, every population faces lim- iting factors and a carrying capacity (p. 58), and systems gen- erally operate in self-renewing cycles, not in a linear manner. Many ecological economists advocate economies that do not grow and do not shrink, but rather are stable. Such steady- state economies are intended to mirror natural systems. Ecological economists maintain that quality of life should continue to rise in a steady-state economy, as a result of tech- nological advances and behavioral changes (such as greater

The dramatic rise in per-person consumption has numerous consequences (FIGURE 5.5).

Economic growth stems from two sources: (1) an increase in inputs to the economy (e.g., greater inputs of labor and nat- ural resources) and (2) improvements in the efficiency of pro- duction due to better technologies and approaches (i.e., ideas and equipment that enable us to produce more goods with fewer inputs). This second approach—whereby we produce more with less—is often termed economic development.

As our population and consumption rise, it is becom- ing clearer that we cannot sustain growth forever using the first approach. Nonrenewable resources on Earth are finite in quantity, and there are limits on the rates that we can harvest many renewable resources. As for the second approach, we have used technological innovation to push back the limits on growth time and again. More-efficient technologies for extracting minerals, fossil fuels, and groundwater allow us to exploit these resources more fully with less waste. Automated farm machinery, fertilizers, and chemical pesticides enable us to grow more food per unit area of land (p. 136). Better ma- chinery in our factories speeds our manufacturing. We con- tinue to make computer chips more powerful while also mak- ing them smaller and using fewer raw materials. In all these ways, we are producing more goods and services while using fewer resources.

Causes Consequences

Solutions

As you progress through this chapter, try to identify as many solutions to rising per capita consumption as you can. What could you personally do to help address this issue? Consider how each action or solution might affect items in the concept map above.

Globalization and trade

Advertising

Idea that all growth is good

New technologies More resource

extraction

More manufacturing

More agricultural production

Social disruption

Health impacts

More resource extraction

More fossil fuel use

More waste and pollution

“Affluenza”

Habitat alteration

Global climate change

Economic loss

Loss of biodiversity and

ecosystem services

Rising per capita consumption

FIGURE 5.5  The rise in per-person consumption of goods and services stems from multiple causes (ovals on left) and results in a diversity of environmental, social, and economic consequences (boxes on right). Arrows in this concept map lead from causes to consequences. Note that items grouped within an outlined box do not neces- sarily share any special relationship; the outlined box is intended merely to streamline the figure.

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(TABLE 5.1 and FIGURE 5.6). For example, the aesthetic and recreational pleasure we obtain from natural landscapes is something of real value. Yet because we do not pay money for this, its value is hard to quantify and appears in no tradition- al measures of economic worth. Or consider Earth’s water cycle (p. 37), by which rain fills our reservoirs with drinking water, rivers give us hydropower and f lush away our waste, and water evaporates, purifying itself of contaminants and readying itself to fall again as rain. This natural cycle is vital to our very existence, yet because we do not quantify its val- ue, markets impose no financial penalties when we disturb it.

To resolve this dilemma, environmental and ecologi- cal economists have sought ways to assign values to ecosys- tem services. In one technique, economists use surveys to determine how much people are willing to pay to protect or restore a resource. In another approach, they measure the money, time, or effort people expend to travel to parks for rec- reation. Economists also compare housing prices for similar homes in different environmental settings to infer the dollar value of landscapes, views, and peace and quiet. They may also measure the cost required to restore natural systems that have been damaged, to replace those systems’ functions with tech- nology, or to reduce harm from pollution.

(b) Existence value(a) Use value

(e) Scientific value (f) Educational value (g) Cultural value

FIGURE 5.6  Accounting for nonmarket values such as those shown here may help us to make better environmental and economic decisions. See Table 5.1 for details.

use of recycling) that enhance sustainability. They argue that wealth and human well-being can continue to increase after economic growth has leveled off.

Environmental economists tend to agree with ecologi- cal economists that economies are unsustainable if popula- tion growth is not reduced and resources are not used more efficiently, but they argue that, with effort, we can accomplish these changes and attain sustainability within our current economic systems. By modifying the principles of neoclassi- cal economics to address environmental challenges, environ- mental economists maintain that we can keep our economies growing and that technology can continue to improve effi- ciency. Thus, whereas ecological economists call for revolu- tion, environmental economists call for reform. One approach environmental economists take is to assign monetary values to ecosystem goods and services, so as to better integrate them into traditional cost-benefit analyses.

We can assign monetary value to ecosystem goods and services Ecosystem services are said to have nonmarket values, values not usually included in the market price of a good or service

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TABLE 5.1 Values That Modern Market Economies Generally Do Not Address

Nonmarket value Is the worth we ascribe to things . . .

Use value that we use directly

Existence value simply because they exist, even though we may never experience them di- rectly (e.g., an endangered species in a far-off place)

Option value that we do not use now but might use later

Aesthetic value for their beauty or emotional appeal

Scientific value that may be the subject of scientific research

Educational value that teach us about ourselves or the world

Cultural value that sustain or help define our culture

Ty p e

o f

ec o sy

st em

s er

vi ce

Nutrient cycling

Cultural uses

Waste treatment

Disturbance regulation

Water supply

Food provision

Gas regulation

Water regulation

Recreation

Raw materials

Climate regulation

Erosion control

Biological control

Habitat provision

Pollination

Genetic resources

Soil formation

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 17.0

Total global value per year (trillions of dollars)

For more on ecosystem services, see Figure 2.17 in Chapter 2.

FIGURE 5.7  Environmental economists in 1997 estimated the value of the world’s eco- system services at more than $33 trillion ($46 trillion in 2011 dollars). Shown are subtotals for each major type of ecosystem service. The $33 trillion figure is an underestimate because it does not include values from ecosystems for which adequate data were unavailable. Data from Costanza, R., et al., 1997. The value of the world’s

ecosystem services and natural capital. Nature 387:

253–260.

In 1997, a research team headed by environmental economist Robert Costanza set out to calculate the total eco- nomic value of all the services that oceans, forests, wetlands, and other ecosystems provide across the world. Costanza’s team combed the scientific literature and evaluated over 100 studies that used various methods to estimate dollar values for 17 major ecosystem services such as water purification, climate regulation, plant pollination, and pollution cleanup (FIGURE 5.7). To improve the accuracy of estimates, the re- searchers reevaluated the data using multiple techniques. They then multiplied average estimates for each ecosystem by the global area occupied by each. Their analysis, reported in the journal Nature, calculated that Earth’s biosphere in to- tal provides at least $33 trillion ($46 trillion in 2011 dollars) worth of ecosystem services each year—more than the GDP of all nations combined!

In a follow-up study in 2002, Costanza joined Andrew Balmford and 17 other colleagues to compare the benefits and costs of preserving natural systems versus converting wild lands for agriculture, logging, or fish farming. After reviewing many studies, they reported in the journal Science that a global network of nature reserves covering 15% of Earth’s land sur- face and 30% of the ocean would be worth between $4.4 and $5.2 trillion. This amount is 100 times greater than the value of those areas were they to be converted for direct exploitative human use—demonstrating, in their words, that “conserva- tion in reserves represents a strikingly good bargain.”

Businesses are responding to sustainability concerns As economists rethink old assumptions and as more consumers and investors express preferences for sustainable products and services, many industries, businesses, and corporations are find- ing that they can make money by “greening” their operations.

Some companies have cultivated an eco-conscious image from the start, such as Ben & Jerry’s (ice cream), Patagonia (outdoor apparel), Seventh Generation (household products), and Credo (formerly Working Assets; phone service). In recent years, however, corporate sustainability has gone mainstream, and some of the world’s largest corporations have joined in, in- cluding Ford Motor Company, Toyota, McDonald’s, Starbucks, IKEA, Dow, Dupont, BASF, Intel, and Wal-Mart (FIGURE 5.8). Hewlett-Packard runs programs to reuse and recycle used ton- er cartridges, electronics, and plastics. Nike, Inc., collects mil- lions of used sneakers each year and recycles their materials to create surfaces for basketball courts, tennis courts, and running tracks. The Gap, Inc., built a sustainably designed headquar- ters building, cut energy use in its stores and distribution cent- ers, and promotes alternative transportation for its employees. Today many corporations are finding ways to increase energy

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efficiency, reduce toxic substances, increase the use of recycled materials, and minimize greenhouse gas emissions. In doing so, they often find that they reduce costs and increase profit.

Of course, corporations exist to make money for their shareholders, so they cannot be expected to pursue goals that do not turn a profit. Moreover, many corporate green- ing efforts are more rhetoric than reality, and corporate greenwashing may mislead consumers into thinking a company is acting more sustainably than it is. For instance, the bottled water industry advertises its products with words such as “pure” and “natural.” Images of forests and alpine springs lead us to believe that bottled water is cleaner and healthier for us to drink—when in reality the water is often less safe, the plastic bottles are a major source of waste, oil is used to manufacture and transport the bottles, and the in- dustry depletes aquifers in local communities (pp. 268–269).

In the end, corporate actions hinge on consumer behav- ior. It is up to all of us in our roles as consumers to encour- age trends in sustainability by rewarding those businesses that truly promote sustainable solutions.

Markets can fail When they do not ref lect the full costs and benefits of ac- tions, markets are said to fail. Market failure occurs when markets do not take into account the environment’s positive

FIGURE 5.8  A Wal-Mart cashier bags compact fluorescent bulbs in reusable canvas bags for a customer. Wal-Mart provides the most celebrated recent example of corporate greening efforts. The world’s largest retailer has launched a program to sell organic and sustainable products, reduce packaging and use recycled materi- als, enhance fuel efficiency in its truck fleet, reduce energy use in its stores, power itself with renewable energy, cut carbon dioxide emissions, and preserve one acre of natural land for every acre developed. It is also developing a “sustainability index” to rate its products and inform consumers. Although many remain skeptical of Wal-Mart’s commitment to sustainability, the corporation’s vast reach and its ability to persuade suppliers to alter their practices in order to retain its business mean that any change Wal-Mart enacts could have far-reaching impacts.

contributions to economies (such as ecosystem services) or when they do not ref lect the negative impacts of economic activity on the environment or on people (external costs). Traditionally, market failure has been countered by govern- ment intervention. Governments can restrain corporate be- havior through laws and regulations. They can tax environ- mentally harmful activities. Or, they can design economic incentives that use market mechanisms to promote fairness, resource conservation, and economic sustainability. We will now examine these approaches in our discussion of envi- ronmental policy.

ENVIRONMENTAL POLICY: AN OVERVIEW Economic analysis and scientific research can help us deter- mine when resources are being depleted, ecosystem services are being degraded, or people’s quality of life is declining. Once a society reaches broad agreement that such a problem exists, it may persuade its leaders to try to resolve the prob- lem through the making of policy. Policy consists of a formal set of general plans and principles intended to address prob- lems and guide decision making in specific instances. Public policy is policy made by governments, including those at the local, state, federal, and international levels. Public policy consists of laws, regulations, orders, incentives, and prac- tices intended to advance societal well-being. Environmental policy is policy that pertains to human interactions with the environment. It generally aims to regulate resource use or reduce pollution in order to promote human welfare and/or protect natural systems.

Forging effective environmental policy requires input from science, ethics, and economics. Science provides infor- mation and analysis needed to identify and understand prob- lems and devise solutions. Ethics and economics offer criteria to assess problems and to help clarify how society might like to address them. Government interacts with citizens, organi- zations, and the private sector in various ways to formulate policy (FIGURE 5.9).

Environmental policy addresses issues of fairness and resource use Market capitalism is driven by incentives for short-term eco- nomic gain rather than long-term social and environmental stability. It provides little motivation for businesses or indi- viduals to behave in ways that minimize environmental im- pact or that equalize costs and benefits among parties. As we noted, such market failure has traditionally been viewed as justification for government intervention. Environmental policy aims to protect environmental quality and the natural resources people use, and also to promote equity or fairness in people’s use of resources.

The tragedy of the commons Policy to protect re- sources held and used in common by the public is intended to safeguard them from depletion or degradation. As envi- ronmental scientist Garrett Hardin explained in his 1968

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others. For example, a factory may reap greater profits by discharging waste freely into a river and avoiding paying for waste disposal or recycling. Its actions, however, im- pose external costs (water pollution, decreased fish popula- tions, aesthetic degradation, health risks) on downstream users of the river. U.S.-owned maquiladoras in the Tijuana River watershed dump waste that affects Mexican families downstream (see Figure 5.4). Likewise, wastewater from the growing number of people living in the watershed fur- ther pollutes the river, imposing external costs on fami- lies farther downstream and beachgoers in Mexico and California.

essay “The Tragedy of the Commons” (pp. 3–4), a resource held in common that is accessible to all will eventually be- come overused and degraded. Therefore, he argued, it is in our best interest to develop guidelines for the use of such resources. In Hardin’s example of a common pasture, guide- lines might limit the number of animals each individual can graze or might require pasture users to pay to restore and manage the shared resource. These two concepts—restriction of use and active management—are central to environmental policy today.

Free riders A second reason to develop policy for pub- licly held resources is the free rider predicament. Let’s say a community on a river suffers from water pollution that emanates from 10 different factories. The problem could in theory be solved if every factory voluntarily agreed to re- duce its own pollution. However, once they all begin reduc- ing their pollution, it becomes tempting for any one of them to stop doing so. Such a factory, by avoiding the sacrifices others are making, would in essence get a “free ride.” If enough factories take a free ride, the whole effort will col- lapse. Because of the free rider problem, private voluntary efforts are generally less effective than efforts mandated by public policy, which help ensure that all parties sacrifice equitably.

External costs Environmental policy also aims to promote fairness by eliminating external costs, ensuring that some parties do not use resources in ways that harm

Lobbying, campaign funding,

legal action Policy

Solutions to

environmental problems

GovernmentPrivate sector

Science

Citizenry

Personal actions and consumer choices

Improvements in efficiency

and technology

Votes, lobbying, campaign funding,

legal action

Information and analysis

FIGURE 5.9  Policy plays a central role in how we as a society address environmental problems. Voters, the private sector, and lobbying groups representing various interests influence government representatives. Scientific research also informs government decisions. Governmental representatives and agencies formulate policy that aims to address problems. Public policy—along with improvements in technology and efficiency and personal actions and consumer purchasing choices—can produce lasting solutions to environmental problems.

Do We Really Need Environmental Policy? Many free-market advocates contend that environmental laws and regulations are an undesirable government intrusion into private

affairs. Adam Smith (p. 90) argued that individuals benefit society by pursuing their own self-interest. Do you agree? Can you describe a situation in which an individual acting in self-interest either (a) benefits society by addressing an environmental problem, or (b) harms society by causing an environmental problem? How might policy help in either situation? What are some advantages and disadvantages of environmental laws and regulations?

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the right to manage unsettled lands and created a grid system for surveying them and readying them for private ownership. Between 1785 and the 1870s, the federal gov- ernment promoted settlement on lands it had expropri- ated from Native Americans, and it doled out these lands to its citizens. Western settlement provided these citizens with means to achieve prosperity while relieving crowding in Eastern cities. It expanded the geographical reach of the United States at a time when the young nation was still jos- tling with European powers for control of the continent. It also wholly displaced the millions of Native Americans who had long inhabited these lands. U.S. environmental policy of this era reflected the public perception that Western lands were practically infinite and inexhaustible in natu- ral resources. Laws encouraged settlers, entrepreneurs, and land speculators to move west, and this hastened the closing of the frontier.

The second wave of U.S. environmental policy encouraged conservation In the late 1800s, as the continent became more populated and its resources were increasingly exploited, public per- ception and government policy toward natural resources began to shift. Laws of this period aimed to alleviate some of the environmental impacts associated with westward expansion.

In 1872, Congress designated Yellowstone as the world’s first national park. In 1891, Congress passed a law authorizing the president to create “forest reserves” in order to prevent overharvesting and protect forested watersheds. In 1903, Pres- ident Theodore Roosevelt created the first national wildlife refuge. These acts enabled the creation of a national park sys- tem, national forest system, and national wildlife refuge sys- tem that still stand as global models (pp. 193, 200). These de- velopments reflected a new understanding that the continent’s resources were exhaustible and required legal protection.

Land management policies continued through the 20th century, addressing soil conservation in the Dust Bowl years (p. 141) and wilderness preservation through the Wilderness Act of 1964 (p. 200), which sought to preserve pristine lands “untrammeled by man, where man himself is a visitor who does not remain.”

The third wave responded to pollution Further social changes in the 20th century gave rise to the third major period of U.S. environmental policy. In a more densely populated nation driven by technology, heavy indus- try, and intensive resource consumption, Americans found themselves better off economically but living with dirtier air, dirtier water, and more waste and toxic chemicals. Dur- ing the 1960s and 1970s, several events triggered increased awareness of environmental problems and brought about a shift in public policy.

A landmark event was the 1962 publication of Silent Spring, a book by American scientist and writer Rachel Carson (FIGURE 5.11). Silent Spring awakened the public to the nega-

U.S. ENVIRONMENTAL LAW AND POLICY The United States provides a good focus for understanding environmental policy in constitutional democracies world- wide, for several reasons. First, the United States has pio- neered innovative environmental policy. Second, U.S. poli- cies have served as models—of both success and failure—for other nations and international government bodies. Third, the United States exerts a great deal of inf luence on the affairs of other nations. Finally, understanding U.S. environmental policy at the federal level helps us understand it at local, state, and international levels.

The three branches of the U.S. federal government— legislative, executive, and judicial—are each involved in as- pects of environmental policy. Once legislation, or statutory law, is passed by Congress and signed into law by the presi- dent, its implementation and enforcement is assigned to an administrative agency within the executive branch. Adminis- trative agencies are the source of a great deal of policy, in the form of regulations, specific rules intended to help achieve the objectives of the more broadly written statutory law. Be- sides issuing regulations, administrative agencies monitor compliance with laws and regulations and enforce them when they are violated. The judicial branch interprets law as needed in response to suits in the courts.

The structure of the federal government is mirrored at the state level with governors, legislatures, judiciaries, and agencies. State laws cannot violate principles of the U.S. Constitution, and if state and federal laws conflict, federal laws take precedence. Many states with dense urban popula- tions, such as California, New York, New Jersey, and Mas- sachusetts, have strong environmental laws and well-funded environmental agencies. Citizens of such states put more emphasis on safeguarding environmental quality because they have witnessed extensive environmental degradation in the past.

To safeguard public health in locations such as San Diego’s beaches, California’s state legislators have required state envi- ronmental health officials to set standards and test waters for bacterial contamination. Officials issue an advisory, or warn- ing, when bacterial concentrations in nearshore waters exceed health limits established by California law. As we proceed through our discussion of federal policy, keep in mind that important environmental policy is also created at the state and local levels.

Early U.S. environmental policy promoted development The laws that comprise U.S. environmental policy were cre- ated largely in three periods. Laws enacted during the first period, from the 1780s to the late 1800s, accompanied the westward expansion of the nation and were intended mainly to promote settlement and the use of the continent’s abun- dant natural resources (FIGURE 5.10).

Among these early laws were the General Land Ordi- nances of 1785 and 1787, which gave the federal government

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tive ecological and health effects of pesticides and industrial chemicals (p. 210). The book’s title refers to Carson’s warning that pesticides might kill so many birds that few would be left to sing in springtime.

Ohio’s Cuyahoga River (FIGURE 5.12) also drew attention to pollution hazards. The Cuyahoga was so polluted with oil and industrial waste that the river actually caught fire near Cleveland a number of times in the 1950s and 1960s. This spectacle, coupled with an oil spill offshore from Santa Bar- bara, California, in 1969, moved the public to urge Congress and the president to do more to protect the environment. The first Earth Day in 1970 helped to galvanize public support for action to address pollution problems.

Today, largely because of environmental policies enacted since the 1960s, public health is better protected and the na- tion’s air and water are considerably cleaner. All of us alive today owe a great deal to the dedicated people who designed policy to tackle pollution problems during this period.

(a) Settlers in Custer County, Nebraska, circa 1860

(b) Nineteenth-century mining operation, Lynx Creek, Alaska

FIGURE 5.10  The Homestead Act of 1862 allowed settlers (a) to claim, for a $16 fee, 65 ha (160 acres) of public land by living there for five years and cultivating the land or building a home. The General Mining Act of 1872 legalized and promoted mining (b) by private individuals on public land for just $5 per acre, sub- ject to local customs, with no govern- ment oversight. Although the Timber Culture Act of 1873 promoted tree planting on settled lands, elsewhere the timber industry was allowed to clear-cut the nation’s ancient trees (c) with little government policy to limit logging or encourage replanting or conservation.

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Q: Isn’t the EPA an advocate for the environment? A: Like all administrative agencies, the EPA is part of the executive branch and operates in line with the policies of the presidential administration in power at the time. As such, the EPA under a conservative president may function very differently from the EPA under a liberal one. Indeed, sometimes the agency may impede environmental regulations! The EPA employs many career scientists who carry out careful scientific research and make scientifically informed policy recommendations. They advise administrators appointed by the president, however, and policy decisions are ultimately made by these politically appointed administrators.

FAQ

Other prominent laws followed Ongoing public demand for a cleaner environment during this period resulted in a number of key laws that remain fun- damental to U.S. environmental policy ( FIGURE 5.13 ). For river pollution problems like those of the Tijuana River, a crucial law has been the Clean Water Act of 1977. Prior to passage of federal laws such as the Clean Water Act, pollution problems were left largely to local and state governments or

FIGURE 5.12  In a spectacular display of the need for better control over water pollution, Ohio’s Cuyahoga River caught fire multiple times in the 1950s and 1960s. The Cuyahoga was so pol- luted with oil and industrial waste that the river would burn for days at a time.

report of results from studies that assess the potential envi- ronmental impacts that would likely result from development projects undertaken or funded by the federal government.

NEPA’s effects have been far-reaching. The EIS process forces government agencies and businesses that contract with them to evaluate environmental impacts before proceeding with a new dam, highway, or construction project. Although the EIS process generally does not halt such projects, it can serve as an incentive to minimize environmental damage. NEPA also grants ordinary citizens input in the policy proc- ess by requiring that EISs be made publicly available and that policymakers solicit and consider public comment on them.

Creation of the EPA marked a shift in environmental policy Six months after signing NEPA into law, Nixon issued an executive order calling for a new integrated approach to en- vironmental policy. “The Government’s environmentally related activities have grown up piecemeal over the years,” the order stated. “The time has come to organize them ra- tionally and systematically.” Nixon’s order moved elements of agencies regulating water quality, air pollution, solid waste, and other issues into the newly created Environmen- tal Protection Agency (EPA) . The order charged the EPA with conducting and evaluating research, monitoring envi- ronmental quality, setting and enforcing standards for pol- lution levels, assisting the states in meeting standards and goals, and educating the public.

NEPA gives citizens input into policy decisions Besides Earth Day, two federal actions marked 1970 as the dawn of the modern era of environmental policy in the United States. On January 1, 1970, President Richard Nixon signed the National Environmental Policy Act (NEPA) into law. NEPA created an agency called the Council on Environ- mental Quality and required that an environmental impact statement (EIS) be prepared for any major federal action that might significantly affect environmental quality. An EIS is a

FIGURE 5.11  Scientist and writer Rachel Carson illuminated the problem of pollution from DDT and other pesticides in her 1962 book, Silent Spring .

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By the 1990s, the political climate in the United States had changed. Although public support for the goals of environ- mental protection remained high, many citizens and policy experts began to feel that the legislative and regulatory means used to achieve these goals often imposed economic burdens on businesses or individuals. Increasingly, attempts were made to roll back or weaken environmental laws, culminat- ing in an array of efforts by the George W. Bush administra- tion and the Republican-controlled Congresses in power from 1994 through 2006.

As advocates of environmental protection watched their hard-won gains eroding, many began to propose new perspec- tives and strategies. In a provocative 2004 essay titled “The Death of Environmentalism,” political consultants Michael Shellenberger and Ted Nordhaus argued that environmental advocates needed to stop simply offering technical policy fixes and instead needed to appeal to people’s core values and artic- ulate a positive, inspiring vision for the future. These sugges- tions opened a spirited discussion, and in 2008 Barack Obama embraced a similar approach in his presidential campaign.

As the United States’ international leadership in envi- ronmental policy has waned in recent decades, other nations have enhanced their attention to environmental issues. The 1992 Earth Summit at Rio de Janeiro, Brazil, and the 2002 World Summit on Sustainable Development in Johannes- burg, South Africa, were the largest diplomatic conferences ever held, unifying leaders from 200 nations around the idea of sustainable development (pp. 17, 414). Internationally, we are embarking on a new wave of environmental policy, one focused on sustainability and sustainable development. This approach aims to safeguard natural systems while raising liv- ing standards for the world’s people. Moreover, the press- ing issue of global climate change (Chapter 14) has come to dominate much of the world’s discussion over environmental policy (FIGURE 5.14). As we continue to feel the social, eco- nomic, and ecological effects of environmental degradation,

were addressed through lawsuits. The f laming waters of the Cuyahoga, however, indicated to many people that tough leg- islation was needed. Thanks to restrictions on pollutants by the Federal Water Pollution Control Acts of 1965 and 1972, and then the Clean Water Act, U.S. waterways finally began to recover. These laws regulated the discharge of wastes, espe- cially from industry, into rivers and streams. The Clean Wa- ter Act also aimed to protect wildlife and establish a system for granting permits for the discharge of pollutants. Today thousands of federal, state, and local laws and regulations help protect health and environmental quality in the United States and abroad.

The social context for policy evolves over time Historians suggest that major advances in environmental policy occurred in the 1960s and 1970s because (1) evidence of environmental problems became widely and readily appar- ent, (2) people could visualize policies to deal with the prob- lems, and (3) the political climate was ripe, with a supportive public and leaders who were willing to act. In addition, pho- tographs from the space program allowed humanity to see, for the first time ever, images of the Earth from space (see photos on pp. 1 and 418). It is hard for us today to compre- hend the power of those images at the time, but they revolu- tionized many people’s worldviews by making us aware of the finite nature of our planet.

1965

1966

1967

1968

1969

1963

1964

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

Key Environmental Protection Laws, 1963–1980

Wilderness Act

Federal Water Pollution Control Act, Solid Waste Disposal Act

Wild and Scenic Rivers Act

National Environmental Policy Act

Marine Mammal Protection Act, Federal Pesticide Act

Clean Water Act, Soil and Water Conservation Act

Endangered Species Act

Safe Drinking Water Act

Toxic Substances Control Act

CERCLA (“Superfund”)

Clean Air Act

FIGURE 5.13  Many of the most influential laws in modern U.S. environmental policy were enacted in the 1960s and 1970s.

FIGURE 5.14  College students and activists at the 2009 Power Shift event in Washington, D.C., urge U.S. leaders to enact policies to help bring the atmosphere’s carbon dioxide concentration back down to 350 parts per million. This was one of several major events in recent years that expressed grassroots support for addressing global climate change through the political process.

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TABLE 5.2 Some Major International Environmental Treaties Convention or Protocol Year it came into force Nations that have ratified it U.S. status

Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (p. 177)

1975 175 Ratified

Ramsar Convention on Wetlands of Inter- national Importance

1975 159 Ratified

Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol), of the Vienna Convention for the Protection of the Ozone Layer (pp. 290–291)

1989 196 Ratified

Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal (pp. 15, 394)

1992 172 Signed but has not ratified

Convention on Biological Diversity (p. 177) 1993 168 Signed but has not ratified

Stockholm Convention on Persistent Organic Pollutants (p. 223)

2004 152 Signed but has not ratified

Kyoto Protocol, of the U.N. Framework Convention on Climate Change (pp. 318–319)

2005 184 Signed but has not ratified

Several organizations shape international environmental policy A number of international organizations act to inf luence the policy and behavior of nations by providing funding, apply- ing political or economic pressure, and/or directing media attention.

The United Nations Founded in 1945 and including representatives from all nations of the world, the United Nations (U.N.) seeks “to maintain international peace and security; to develop friendly relations among nations; to cooperate in solving international economic, social, cul- tural and humanitarian problems and in promoting respect for human rights and fundamental freedoms; and to be a centre for harmonizing the actions of nations in attaining these ends.”

Headquartered in New York City, the U.N. plays an ac- tive role in international environmental policy by sponsoring conferences, coordinating treaties, and publishing research. An agency within it, the United Nations Environment Pro- gramme (UNEP), promotes sustainability with research and outreach activities that provide information to policymakers and scientists throughout the world.

The World Bank Established in 1944 and based in Washington, D.C., the World Bank is one of the largest sourc- es of funding for economic development. This institution shapes environmental policy through its funding of dams, irrigation infrastructure, and other major projects. In fiscal year 2010, the World Bank provided $59 billion in loans and support for projects designed to benefit the poorest people in the poorest countries.

Despite its admirable mission, the World Bank has fre- quently been criticized for funding projects that cause more environmental problems than they solve, such as dams that

environmental policy and the search for sustainable solutions will become central parts of governance and everyday life for all of us in the years ahead.

INTERNATIONAL ENVIRONMENTAL POLICY Environmental systems pay no heed to political boundaries. For instance, most of the world’s major rivers cross inter- national borders. As a result, environmental problems like those along the Tijuana River are frequently international in scope. Because U.S. law has no authority in Mexico or any other nation outside the United States, international law is vi- tal to solving transboundary problems.

International law includes customary law and conventional law International law known as customary law arises from long- standing practices, or customs, held in common by most cul- tures. International law known as conventional law arises from conventions, or treaties, into which nations enter. One example is the Montreal Protocol, a 1987 accord among more than 160 nations to reduce the emission of airborne chemi- cals that thin the ozone layer (pp. 290–291). Another example is the Kyoto Protocol to reduce greenhouse gas emissions that contribute to global climate change (pp. 318–319). TABLE 5.2 shows a selection of major environmental treaties.

The South Bay International Wastewater Treatment Plant that treats wastewater from the Tijuana River watershed was built as a result of a 1990 treaty between Mexico and the United States. Many social, economic, and environmental issues along the U.S.–Mexican border are influenced by the 1994 North American Free Trade Agreement (NAFTA) (see THE SCIENCE BEHIND THE STORY, pp. 106–107).

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Trade Barriers and Environmental Protection If Nation A has stricter laws for environmental protection than Nation B, and if these laws restrict the ability of Nation B to export

its goods to Nation A, then by the policy of the WTO and the EU, Nation A’s environmental protection laws can be overruled in the name of free trade. Do you think this is right? What if Nation A is a wealthy industrialized country and Nation B is a poor developing country that needs every economic boost it can get?

SCIENCE AND THE ENVIRONMENTAL POLICY PROCESS In constitutional democracies such as the United States, every person has a political voice and can make a difference. However, money wields influence, and some people and organizations are far more influential than others. We will explore some of these dynamics as we examine the main steps of the policymaking process and the role that science plays in policy.

Policy results from a stepwise process Environmental policy involves a multiple-step process that requires initiative, dedication, and the support of many peo- ple (FIGURE 5.15).

➊ Identify a problem The first step in the policy process is to identify an environmental problem. This requires curiosity, observation, record keeping, and an awareness of our relationship with the environment—so scientific inquiry and data collection play key roles. For example, assessing the contamination of San Diego- and Tijuana- area beaches required detecting the contamination, rec- ognizing the ecological and health impacts of untreated wastewater, and understanding water f low dynamics among the beaches, the Pacific Ocean, and the Tijuana River watershed.

waste dump in their neighborhood. Not all such courtroom challenges succeed, but NAFTA’s Chapter 11 cases have discouraged states and nations from passing new environ- mental protection laws.

Nongovernmental organizations A number of non- governmental organizations (NGOs) have become inter- national in scope and exert inf luence over international environmental policy. Some, such as the Nature Conserv- ancy, focus on accomplishing conservation objectives on the ground (in its case, purchasing and managing land and habi- tat for rare species) without becoming politically involved. Other groups, such as Conservation International, the World Wide Fund for Nature, Greenpeace, and Population Connec- tion, attempt to shape policy through research, education, lobbying, or protest.

flood valuable forests and farmlands in order to provide electricity. Providing for the needs of growing populations in poor nations while minimizing damage to the environ- mental systems on which people depend can be a tough balancing act. Environmental scientists today agree that sustainable development must be the guiding principle for such efforts.

The European Union The European Union (EU) seeks to promote Europe’s unity and its economic and social progress (including environmental protection) and to “as- sert Europe’s role in the world.” The EU can sign binding treaties on behalf of its 27 member nations and can enact regulations that have the same authority as national laws. The EU’s European Environment Agency addresses waste management, noise pollution, water pollution, air pollu- tion, habitat degradation, and natural hazards. The EU also seeks to remove trade barriers among member nations. It has classified some nations’ environmental regulations as barriers to trade, arguing that the stricter environmental laws of some northern European nations limit the import and sale of environmentally harmful products from other member nations.

The World Trade Organization Based in Geneva, Swit- zerland, the World Trade Organization (WTO) represents multinational corporations and promotes free trade by reduc- ing obstacles to international commerce and enforcing fair- ness among nations in trading practices. Whereas the United Nations and the European Union have limited inf luence over nations’ internal affairs, the WTO has authority to impose financial penalties on nations that do not comply with its di- rectives. These penalties can affect environmental policy.

Like the EU, the WTO has interpreted some national environmental laws as unfair barriers to trade. For instance, in 1995 the U.S. EPA issued regulations requiring cleaner- burning gasoline in U.S. cities, following Congress’s amend- ments of the Clean Air Act. Brazil and Venezuela filed a complaint with the WTO, saying the new rules discriminat- ed against the petroleum they exported to the United States, which did not burn as cleanly. The WTO agreed, ruling that even though the South American gasoline posed a threat to human health in the United States, the EPA rules were an illegal trade barrier. The ruling forced the United States to weaken its regulations. Not surprisingly, critics have fre- quently charged that the WTO aggravates environmental problems.

International treaties to promote commerce allow in- dustries and corporations to weaken environmental protec- tion laws if they view them as barriers to trade. Chapter 11 of NAFTA allows an investor in one country to sue another country if its laws hinder the investor’s ability to make prof- its. Canada’s cattle industry demanded $300 million from U.S. taxpayers for banning Canadian beef after mad cow disease was found in it. A Canadian producer of a chemi- cal in MTBE, a gasoline additive that California banned to protect public health, sued California for $1 billion in lost profits. A U.S. company forced Mexico to pay it $16 million after local residents refused to let it reopen a toxic

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Identify a problem

Envision solution

Get organized

Cultivate access and influence

Shepherd the solution into law

Pinpoint causes of the problem

Implement, assess, and interpret policy

FIGURE 5.15  Understanding the steps of the policy process is helpful in solving environmental problems.

➋ Pinpoint causes of the problem The next step in the policy process is to discover specific causes of the prob- lem, and this often requires scientific research. A person seeking causes for the Tijuana River’s pollution might no- tice that pollution intensified once U.S.-based companies began opening maquiladoras on the Mexican side of the border. Advocates of the maquiladora system argue that these factories provide much-needed jobs while keeping companies’ costs down by paying Mexican workers low wages. Critics argue that the factories are waste-generat- ing, water-guzzling polluters whose transboundary nature makes them difficult to regulate.

➌ Envision a solution The better one can pinpoint causes of a problem, the more effectively one can envision solutions to it. Science plays a vital role here too, although solutions often rely on social or political action. In San Diego, citi- zen activists wanted Tijuana to enforce its own pollution laws more effectively—something that, once visualized, began to happen when San Diego city employees started training and working with their Mexican counterparts to keep hazardous waste out of the sewage treatment system.

➍ Get organized When it comes to influencing policy, or- ganizations are generally more effective than individuals. Yet small coalitions and even individual citizens who are motivated, informed, and organized can solve environ- mental problems. San Diego-area resident Lori Saldaña provides an example. Concerned about the Tijuana River’s pollution, Saldaña reviewed plans for the international wastewater treatment plant that the U.S. government pro- posed to build. She concluded that it would merely shift pollution from the river to the ocean, where sewage would be released 5.6 km (3.5 mi) offshore. Working with her lo- cal Sierra Club chapter, Saldaña protested the plant’s de- sign and participated in the lawsuit that forced the EPA to conduct further studies and eventually implement design changes. After a decade of activism and work on a com- mission on border issues, Saldaña ran for the California State Assembly in 2004 and won, becoming the represent- ative from California’s 76th district.

➎ Cultivate access and influence The next step in the policy process entails gaining access to policymakers who have the clout to enact change. People gain access and influence through lobbying and campaign contributions. Anyone can spend time or money trying to change an elected of- ficial’s mind, but this is much more difficult for an ordi- nary citizen than for the professional lobbyists employed by businesses and organizations seeking a voice in politics. Supporting a candidate’s reelection efforts with money is another way to make one’s voice heard, and any individual can donate money to political campaigns.

Both of these methods were employed by a private- sector consortium seeking to contract with the U.S. gov- ernment to build a wastewater treatment plant to sup- plement the existing international plant. Backers of this effort, the Bajagua Project, lobbied government officials and gave campaign contributions to California congres- sional representatives, whom they hoped would support their cause. Following years of such efforts, in 2006 the International Boundary and Water Commission agreed

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House of Representatives Senate

Member of House introduces bill

If appropriate, bill is referred to House

committee and subcommittee

Senator introduces bill

If appropriate, bill is referred to Senate

committee and subcommittee

Subcommittee marks changes and

votes on bill

Full committee marks changes and

votes on bill

Subcommittee marks changes and

votes on bill

Full committee marks changes and

votes on bill

Bill is voted on by the full House,

in a House floor vote

House approves final bill

Senate approves final bill

Bill is voted on by the full Senate,

in a Senate floor vote

A conference committee made up of both House and Senate committees that worked on the bill works out any differences between the

House and Senate versions of the bill

The White House The final bill is sent to the President, who either signs or vetoes it. (If the bill is vetoed, a 2/3 majority of the

House and Senate can overturn the veto.)

FIGURE 5.16  Before a bill becomes U.S. law, it must clear hurdles in both legislative bodies. If the bill passes the House and Senate, a conference committee works out differences between House and Senate versions before the bill is sent to the president. The president may then sign or veto the bill.

EPA) implement regulations. Policymakers evaluate the policy’s successes and failures and may revise the policy as necessary. Moreover, courts interpret law in response to lawsuits, and much environmental policy has lived or died by judicial interpretation. As societal and environmental conditions change, the policy process may circle back to its first step as fresh problems are identified, and the proc- ess may begin anew.

Science plays a role in policy but can be misused A nation’s strength depends on its commitment to science, and this is why governments devote a portion of our taxes to fund scientific research. The more information a policy- maker can glean from scientific research, the better policy he or she will be able to craft.

Unfortunately, sometimes policymakers allow ideology alone to determine policy on scientific matters. In 2004, the nonpartisan Union of Concerned Scientists released a state- ment that faulted the George W. Bush administration for ignoring scientific advice; manipulating scientific informa- tion for political ends; censoring, suppressing, and editing reports from government scientists; placing people who were unqualified or had clear conflicts of interest in positions of power; and misleading the public by misrepresenting scien- tific knowledge. More than 12,000 American scientists signed on to this statement. Many government scientists working on politically sensitive issues such as climate change or endan- gered species protection said they had found their work sup- pressed or discredited and their jobs threatened. Many chose self-censorship.

For these reasons, most American scientists greeted the elec- tion of Barack Obama with relief, as Obama spoke of “restoring scientific integrity to government” and ensuring “that scientific data [are] never distorted or concealed to serve a political agen- da.” Of course, either political party can politicize science, and as of 2011, the Union of Concerned Scientists was faulting the Obama administration for failing to fully live up to its promises.

Whenever taxpayer-funded science is suppressed or dis- torted for political ends—by the right or the left—we all lose. Abuses of power generally come to light only when brave government scientists risk their careers to alert the public and when journalists work hard to uncover and publicize these is- sues. We cannot simply take for granted that science will play a role in policy. Scientifically literate citizens of a democracy need to stay vigilant and help make sure our government rep- resentatives are making proper use of the tremendous scien- tific assets we have at our disposal.

APPROACHES TO ENVIRONMENTAL POLICY When most people think of environmental policy, what comes to mind are major laws, such as the Clean Water Act, or government regulations, such as those specifying what a factory can and cannot dump into a river. However, environ- mental policy is far more diverse.

to support the Bajagua Project—although the commission changed its mind two years later.

➏ Shepherd the solution into law The next step is to pre- pare a bill, or draft law, that embodies the desired solu- tions. Anyone can draft a bill, but members of the House and Senate must introduce the bill and shepherd it from subcommittee through full committee and on to passage by the full Congress (FIGURE 5.16). If it passes through all of these steps and gains the president’s signature, the bill becomes law, but it can die in countless fashions along the way.

➐ Implement, assess, and interpret policy Following a law’s enactment, administrative agencies (such as the

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Mexico, the United States, and Canada signed NAFTA to promote free trade among them. NAFTA, which came into force in 1994, eliminated trade barriers such as tariffs on imports and exports. Nations erect tariffs in order to raise prices on foreign goods so that foreign industries won’t drive domestic industries out of business— but if nations can agree to mutu- ally eliminate tariffs, it makes goods cheaper for everyone.

Many people worried that NAFTA threatened to undermine protections for workers and the environment. For instance, if a nation’s regulations to protect environmental quality or worker safety are viewed as a barrier to trade or investment, under NAFTA those regula- tions can potentially be overturned.

Moreover, many people felt that industries, motivated to decrease

costs and increase profits, would move their factories (and jobs) to the nation with the weakest regulations. This could create “pollution havens.” Many people thought Mexico would be overrun by maquiladoras seeking to profit from lax regulation and that Mexico would thereby suffer intensive pollution (see figure). People predict- ed that once such a migration began, this could lead to a “race to the bot- tom” whereby all three nations would begin gutting their regulations in an attempt to lure business. This was part of the reason that NAFTA caused so many blue-collar U.S. workers to fear that their jobs would migrate to Mexico.

In response to these fears, two side agreements for labor and environ- mental concerns were negotiated. The environmental agreement, the North

American Agreement on Environmen- tal Cooperation, set up a tri-national Commission on Environmental Coop- eration (CEC). The CEC has monitored NAFTA’s effects on the environment over the years, testing hypotheses about the impacts that NAFTA was predicted to have. The CEC has held four symposia, for which dozens of researchers have published over 50 research papers analyzing different aspects of the topic.

This research suggests that for the most part, the feared consequences have not occurred or have not been due to NAFTA. Researchers testing for a “race to the bottom” did not find evidence for it. Instead, they found that several measures of environmental quality improved during the 1990s and that NAFTA did not seem to influence these measures.

Researchers also have not found strong evidence for creation of a “pol- lution haven” in Mexico. One reason is that businesses have many factors to weigh when considering whether to

T H E S C I E N CE B E H I N D T H E S TO RY

Assessing the Environmental Impacts of NAFTA

Workers assemble television circuit boards for Panasonic in a maquilado- ra in Tijuana, Mexico.

A number of international treaties address environmental issues (see Table 5.2). But treaties not aimed specifically at environmental concerns may still have major environmental consequences. The North American Free Trade Agreement (NAFTA) is one such treaty.

We follow three types of policy approaches Today’s environmental policy can follow a variety of strate- gies within three major approaches (FIGURE 5.17).

Lawsuits in the courts Prior to the legislative push of recent decades, most environmental policy questions in the United States were addressed with lawsuits in the courts. In- dividuals suffering external costs from pollution would sue polluters, one case at a time. The courts sometimes punished polluters by ordering them to stop their operations or pay damages to the affected individuals. However, as industri- alization proceeded and population grew denser, pollution became harder to avoid, and judges were reluctant to hinder industry. People began to view legislation and regulation as more effective means of protecting public health and safety.

Command-and-control policy Most environmental laws of recent decades, and most regulations enforced by agencies today, use a command-and-control approach. In the

command-and-control approach, an agency prohibits certain actions, or sets rules, standards, or limits, and threatens pun- ishment for violations. This simple and direct approach to policymaking has brought citizens of the United States and many other nations cleaner air, cleaner water, safer work- places, healthier neighborhoods, and many other improve- ments in quality of life. The relatively safe, healthy, comfort- able lives most of us enjoy today owe much to the command- and-control environmental policy of the past few decades.

Economic policy tools Despite the successes of com- mand-and-control policy, many people have grown disen- chanted with the top-down, sometimes heavy-handed, nature of an approach that dictates particular solutions to problems. As a result, political scientists, economists, and policymakers today are exploring alternative approaches that aim to chan- nel the innovation and economic efficiency of market capi- talism in directions that benefit the public. Such economic policy tools use financial incentives to promote desired outcomes, discourage undesired outcomes, and encourage

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Maquiladoras in the border areas of Mexico flourished in the years after NAFTA, employing many people but creating substantial pollution. Perhaps the worst pollution occurred at the site shown here. At this abandoned lead recycling plant, Metales y Derivados, the U.S. owner left 6,600 tons of hazard- ous waste amid a working-class Tijuana neighborhood.

relocate, and environmental regula- tions are merely one of these. Ironi- cally, the one clear case of a pollution haven occurred not in Mexico, but in Canada! Exports of hazardous waste (mostly from steel and chemical factories) from the United States to Canada more than quadrupled soon after NAFTA went into effect. Disposal was cheaper in Canada, with fewer regulations and liability concerns. Canada responded by tightening its regulations.

CEC-sponsored researchers also tested hypotheses that NAFTA might enhance sustainability by facilitat- ing the spread of environmentally superior technology, products, and approaches among nations. Research- ers found plenty of examples. Canada began using the EPA’s Energy Star program (p. 344). Mexico banned the pesticide DDT. Chemical manufactur- ers set up a transnational program for reducing hazards. And the three nations began conferring on how

to protect threatened species and habitats.

Moreover, consumer demand in the United States and Canada for sustainably produced products helped encourage improvement in Mexico. Many Mexican coffee farmers con- verted to sustainable plantations, and researchers found that maquiladoras selling products north of the border made more environmental improve- ments than those selling only in Mexico.

However, despite all this, environ- mental impacts in Mexico grew worse after NAFTA. For instance, air and water pollution from maquiladoras in border areas such as Tijuana increased greatly. Yet, researchers determined that this was due not to a pollution haven or race to the bottom, but to ac- celerated economic growth in Mexico. Consumption and pollution from economic growth simply outpaced the country’s ability to enhance regulation and environmental protection.

Overall, CEC-sponsored research in the years since NAFTA has shown that trade liberalization can lead to environmental improvements, but only if policymakers pay close attention to trends and are ready to make adjust- ments. Opportunities for creating win-win policies that benefit both trade and environmental quality exist, researchers say, and are ready to be seized.

private entities competing in a marketplace to innovate and produce new or better solutions at lower cost.

Each of these three major approaches has strengths and weaknesses, and each is best suited to different conditions. The approaches may also be used together. For instance, gov- ernment regulation is often needed to frame market-based ef- forts, and citizens can use the courts to ensure that regulations are enforced. Let’s now explore several types of economic policy tools.

Green taxes discourage unsustainable activities In taxation, money passes from private parties to the govern- ment, which reapportions it in services to benefit the public. Taxing undesirable activities helps to “internalize” external costs by making them part of the cost of doing business. Taxes on environmentally harmful activities and products are called green taxes. When a business pays a green tax, it is essential- ly reimbursing the public for environmental damage it causes.

Under green taxation, a firm owning a factory that pol- lutes a waterway would pay taxes on the amount of pollution it discharges—the more pollution the higher the tax payment. This gives firms a financial incentive to reduce pollution while allowing them the freedom to decide how to do so. One pol- luter might choose to invest in technologies to reduce its pol- lution if doing so is less costly than paying the taxes. Another polluter might choose to pay the taxes instead—funds the government might then apply toward mitigating pollution in some other way.

Green taxes have yet to gain widespread support in the United States, although similar “sin taxes” on cigarettes and alcohol are tools of U.S. social policy. Taxes on pollution have been widely instituted in Europe, where many nations have adopted the polluter-pays principle, which specifies that the party that pollutes should be held responsible for covering the costs of its impacts. Today there is debate about whether we should implement carbon taxes—taxes on gasoline, coal- based electricity, and fossil-fuel-intensive products—in order to fight climate change (p. 321).

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Permit trading can save money and produce results In the innovative market-based approach known as permit trading, the government creates a market in permits for an environmentally harmful activity, and companies, utili- ties, or industries are allowed to buy, sell, or trade rights to conduct the activity. For instance, to decrease emissions of air pollutants, a government might grant emissions permits and set up an emissions trading system. In a cap-and-trade emissions trading system, the government first determines the overall amount of pollution it will accept (i.e., it caps the total amount of pollution allowed) and then issues permits to polluters that allow them each to emit a certain fraction of that amount. Polluters may exchange these permits with other polluters, and each year the government may reduce the amount of overall emissions allowed (Figure 14.23, p. 321).

Suppose, for example, you are a plant owner with permits to release 10 units of pollution, but you find that you can be- come more efficient and release only 5 units instead. You then have a surplus of permits, which might be very valuable to some other plant owner who is having trouble reducing pollu-

Sue factory in court seeking damages and/or injunction.

PROBLEM: Pollution from factory harms people’s health SOLUTIONS: Three policy approaches

Government regulation restricts emissions allowed.2

Market-based approaches: factories that pollute less outcompete polluting factory through permit-trading, avoiding green taxes, collecting subsidies, or selling ecolabeled products. Polluting factory must find ways to cut emissions to survive in marketplace.

EPA

FIGURE 5.17  For any given environmental problem, such as pol- lution from a factory, we may consider three major types of policy approaches: ➊ seeking compensation through lawsuits, ➋ limiting pollution through command-and-control legislation and regulation, and ➌ reducing pollution through market-based or other economic strategies.

Green taxation provides incentive for industry to lower emissions not merely to a level specified in a regulation, but to still lower levels. However, green taxes do have drawbacks. One is that businesses will most likely pass on their tax ex- penses to consumers.

Subsidies promote certain activities Another type of economic policy tool is the subsidy, a gov- ernment giveaway of money or resources that is intended to encourage a particular industry or activity. Subsidies take many forms, and one is the tax break. Relieving the tax bur- den on an industry, firm, or individual assists it by reducing its expenses.

Subsidies can be used to promote environmentally sus- tainable activities, but all too often they are used to prop up unsustainable ones. In the United States, subsidies for timber extraction (pp. 193–194), grazing (p. 144), and mineral ex- traction (pp. 241–242) on public lands all benefit private par- ties while often degrading publicly held resources. Fossil fuel industries have benefited as well. From 2002 to 2008, the U.S. government gave $72 billion of its citizens’ money—$240 per person—to fossil fuel corporations, while spending only $29 billion on renewable energy efforts. About $54 billion of the fossil fuel subsidies were in the form of tax breaks.

In total, the world’s governments spend roughly $1.45 trillion each year on subsidies judged to be harmful to the environment and to the economy, according to environmen- tal scientists Norman Myers and Jennifer Kent—an amount larger than the economies of all but five nations. The average U.S. taxpayer pays $2,000 per year in environmentally harm- ful subsidies, plus $2,000 more through increased prices for goods and through degradation of ecosystem services, Myers and Kent estimate.

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Emissions after first year of cap-and-trade program Allowances allocated

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FIGURE 5.18  Emissions of sulfur dioxide from sources partici- pating in the emissions trading program mandated by the 1990 Clean Air Act amendments have fallen 64% since 1990. As of 2009, emissions throughout the United States had dropped well below the amount allocated in permits (black line). Data from U.S. Environ- mental Protection Agency.

A License to Pollute? Some environmental advocates oppose emissions trading because they view it as giving polluters “a license to pol- lute.” How do you feel about emissions trading

as a means of reducing air pollution? Would you favor command-and-control regulation instead? What advan- tages and disadvantages do you see in each approach?

FIGURE 5.19  Ecolabeling gives consumers information on products with low environmental impact and enables consumers to encourage more sustainable business practices through their pur- chasing decisions. Organic juices are just one example of ecolabeled products that have become widely available in the marketplace.

tion or who wants to expand production. In such a case, you can sell your extra permits. Doing so generates income for you and meets the needs of the other plant, while the total amount of pollution does not increase. By providing companies an economic incentive to find ways to reduce emissions, permit trading can reduce expenses for both industry and the public relative to a conventional regulatory system.

A cap-and-trade system for sulfur dioxide has been in place in the United States since 1995, established by amendments to the Clean Air Act (p. 283) that mandated lower emissions of this air pollutant, which contributes to acid deposition (pp. 291–294). Since then, sulfur dioxide emissions from sources in the program have declined by 64% (FIGURE 5.18), sulfate deposition has been reduced, and air quality and visibility have improved. The cuts were attained at much less cost than was predicted, with no apparent effect on electricity supply or eco- nomic growth. Savings from the permit trading system are es- timated at billions of dollars per year, and the EPA calculates that the program’s benefits outweigh its costs by about 40 to 1.

Currently, European nations are operating a market in car- bon emissions in an effort to address climate change (p. 321). Some U.S. industries take part in carbon trading through the Chicago Climate Exchange, and emissions trading programs are being established by coalitions of U.S. states (p. 321). Ecolabeling empowers consumers

Another strategy that uses the marketplace to counteract market failure allows consumers to play the key role. When manufacturers designate on their labels how their products were grown, harvested, or manufactured, this approach— called ecolabeling—tells consumers which brands use envi- ronmentally benign processes (FIGURE 5.19). By preferentially buying ecolabeled products, consumers provide businesses a powerful incentive to switch to more sustainable processes. One early example of this was labeling cans of tuna as “dol- phin-safe,” indicating that the methods used to catch the tuna avoid the accidental capture of dolphins. Other common ex- amples include labeling recycled paper (p. 387), organic foods (pp. 154–157), and lumber harvested through sustainable for- estry (pp. 197–199).

Market incentives also operate at the local level You may have already taken part in transactions involving fi- nancial incentives as policy tools. Many municipalities charge residents for waste disposal according to the amount of waste they generate. Other cities place taxes or disposal fees on items whose safe disposal is costly, such as tires and motor oil. Still oth- ers give rebates to residents who buy water-efficient appliances, because the rebates cost the city less than upgrading its waste- water treatment system. Likewise, power companies sometimes offer discounts to customers who buy high-efficiency lightbulbs and appliances, because doing so is cheaper for the utilities than expanding the generating capacity of their plants.

The creative use of economic policy tools is growing at all levels, while command-and-control regulation and legal ac- tion in the courts continue to play vital roles in environmental policymaking. As a result, we have a variety of effective policy strategies we can consider as we seek sustainable solutions to our society’s challenges.

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services, are helping to bring economic approaches to bear on environmental protection and resource conservation. Equat- ing economic well-being with economic growth, as econo- mists and policymakers traditionally have, suggests that economic well-being entails a trade-off with environmental quality. However, as modern scientific, economic, and politi- cal efforts proceed, they are helping us to see that safeguard- ing environmental quality helps to promote our quality of life.

➤ CONCLUSION Environmental policymaking is a problem-solving pursuit that makes use of science, ethics, and economics and that re- quires an astute understanding of the political process. Con- ventional command-and-control approaches of legislation and regulation remain the most common policy approaches, but innovative economic policy tools are increasingly being developed. These tools, as well as efforts of environmental and ecological economists to quantify the value of ecosystem

6. Summarize the differences among the first, second, and third waves of environmental policy in U.S. history. De- scribe two current priorities in international environ- mental policy.

7. What did the National Environmental Policy Act accom- plish? Brief ly describe the origin and duties of the U.S. Environmental Protection Agency.

8. List the steps of the environmental policy process, from identification of a problem through the implementation, assessment, and interpretation of policy.

9. Compare and contrast the three major approaches to environmental policy: lawsuits, command-and-control policy, and economic policy tools. Describe an advantage and disadvantage of each.

10. Differentiate among a green tax, a subsidy, a tax break, and an emissions permit.

T E S T I N G Y O U R C O M P R E H E N S I O N

1. Name two key ways in which human economies are linked to the natural environment.

2. Describe four ways in which critics maintain that neo- classical economic approaches can worsen environmen- tal problems.

3. Compare and contrast the views of neoclassical econo- mists, environmental economists, and ecological econ- omists, particularly regarding the issue of economic growth.

4. What are ecosystem services? Give several examples. Describe how some economists have tried to assign monetary worth to nonmarket values and ecosystem services.

5. Describe and critique three common justifications for environmental policy. Explain the concept of external costs, and state why it is relevant to environmental policy.

4. Compare the roles of the United Nations, the Europe- an Union, the World Bank, the World Trade Organi- zation, and nongovernmental organizations. If you could gain the support of just one of these institutions for a policy you favored, which would you choose? Why?

5. THINK IT THROUGH You have just been elected to the U.S. House of Representatives. People in your district suffer an unusual amount of water pollution from un- treated municipal wastewater, chemical discharges from factories, and oil spillage from commercial and recrea- tional boats. What policy approaches would you choose to pursue to search for solutions to these problems? Give reasons for your choices.

S E E K I N G S O L U T I O N S

1. Do you think that a steady-state economy is a practical alternative to our current approach that prioritizes eco- nomic growth? Why or why not?

2. Do you think we should attempt to quantify and assign market values to ecosystem services and other enti- ties that have only nonmarket values? Why or why not?

3. Ref lect on the causes for the transitions in U.S. history from one type of environmental policy to another. Now peer into the future, and think about how life might be different in 25, 50, or 100 years. What would you specu- late about the environmental policy of the future? What issues might it address? Do you predict we will have more or less environmental policy?

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Go to www.masteringenvironmentalscience.com for homework assignments, practice quizzes, Pearson eText, and more.

C A L C U L A T I N G E C O L O G I C A L F O O T P R I N T S

The League of Conservation Voters is a nongovernmental or- ganization that tracks the voting records of U.S. policymakers on environmental issues and provides information to citizens. It is an advocacy organization, and you may or may not agree with its positions, but its website provides an easy way to track the votes of your Congressional representatives on bills

dealing with environmental policy. Go to the LCV’s website at http://www.lcv.org. Under “Scorecard,” click on the link for the most recent year. Find the representatives for your state, and click on their names to explore their voting records. The Y’s and N’s show how they voted on key bills. To read descriptions of the bills, click on the links for those bills.

Voting Records of Your Congressional Representatives Name of Congressperson How he/she voted on your bill

of interest A member of the U.S. House of Representatives from your state A U.S. senator from your state A member of the Congressional leadership

1. After exploring the voting records of your state’s repre- sentatives in the House, find one vote that you disagree with. In the first row of the table, write the representa- tive’s name and describe his or her vote on your bill of interest. What do you disagree with, and why?

2. Next, explore the voting records of your state’s two U.S. senators, and find one vote that you disagree with. In the second row of the table, write the senator’s name and describe his or her vote on your bill of interest. What do you disagree with, and why?

3. For one of these issues, outline a letter that you would write to your Congressional representative explaining why you feel he or she should support your position on the issue.

4. The League of Conservation Voters advocates particular positions. Did you find cases in which you would take a position that differs from theirs? If so, what did you dis- agree with, and why?

5. Select one of the bills you see described, and explain how you think passage of the bill might inf luence the ecologi- cal footprint of people in your state.

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Crowded street in Guangzhou, one of China’s largest cities

6 Human PopulationUpon completing this chapter, you will be able to: ➤ Perceive the scope of human population growth ➤ Evaluate how human population, affluence, and technology affect the environment ➤ Explain and apply the fundamentals of demography ➤ Outline and assess the concept of demographic transition

➤ Describe how wealth and poverty, the status of women, and family-planning affect population growth

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When Mao Zedong founded the country’s cur- rent regime 63 years earli- er, roughly 540 million peo- ple lived in a mostly rural, war-torn, impoverished na- tion. Mao believed popula- tion growth was desirable, and under his leadership China grew and changed. By 1970, improvements in food production, food dis- tribution, and public health allowed China’s population to swell to 790 million peo- ple. At that time, the average Chinese woman gave birth to 5.8 children in her lifetime.

However, the country’s burgeoning population and its industrial and agricultural development were eroding the nation’s soils, depleting its water, lev- eling its forests, and polluting its air. Chinese leaders realized that the nation might not be able to feed its people if their numbers grew much larger. They saw that continued population growth could exhaust re- sources and threaten the stability and progress of Chinese society. The government decided in 1970 to institute a population control program that prohib- ited most Chinese couples from having more than one child.

The program began with education and outreach efforts encouraging people to marry later and have fewer children. Along with these efforts, the Chinese government increased the accessibility of contracep- tives and abortion. By 1975, China’s annual popula- tion growth rate had dropped from 2.8% to 1.8%.

To further decrease birth rates, in 1979 the government took the more drastic step of instituting a system of rewards and punishments to enforce a one-child limit. One-child families received better access to schools, medical care, housing, and govern- ment jobs. Mothers with only one child were given longer maternity leaves. Families with more than one child, meanwhile, were

subjected to monetary fines, employment discrimina- tion, and social scorn and ridicule. In some cases, the fines exceeded half of a couple’s annual income.

Population growth rates dropped still further, but public resistance to the policy was simmering. Be- ginning in 1984, the one-child policy was loosened, strengthened, and then loosened again, as government leaders sought to maximize population control while minimizing public opposition. Today the one-child pro- gram is less strict than in past years and applies mostly to families in urban areas. Many farmers and ethnic mi- norities in rural areas are exempted, because success on the farm often depends on having multiple children.

In enforcing its policies, China has been conduct- ing one of the largest and most controversial social experiments in history. In purely quantitative terms, the experiment has been a success: The nation’s growth rate is now down to 0.5%, making it easier for the country to deal with its many social, economic, and environmental challenges.

CE N T R A L C A S E S T U DY

China’s One-Child Policy “Population growth is analogous to a plague of locusts. What we have on this earth today is a plague of people.”

—Ted Turner, Media Magnate and Supporter of the United Nations Population Fund

“As you improve health in a society, population growth goes down. . . . Before I learned about it, I thought it was paradoxical.”

—Bill Gates, Chair, Microsoft Corporation

T he People’s Republic of China is the world’s most populous nation, home to one-fifth

of the 7 billion people living on Earth at the start of 2012.

China

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However, the one-child policy has also produced un- intended consequences. Traditionally, Chinese culture has valued sons because they carry on the family name, assist with farm labor in rural areas, and care for aging parents. Daughters, in contrast, will most likely marry and leave their parents, as the culture dictates. As a result, they cannot provide the same benefits to their parents as will sons. Thus, faced with being limited to just one child, many Chinese couples prefer a son to a daughter. Tragi- cally, this has led to selective abortion, killing of female in- fants, an unbalanced sex ratio, and a black-market trade in teenaged girls for young men who cannot find wives.

Further problems are expected in the near future, including an aging population and a shrinking work- force. Moreover, China’s policies have elicited intense criticism worldwide from people who oppose govern- ment intrusion into personal reproductive choices.

As other nations become more and more crowd- ed, might their governments also feel forced to turn to drastic policies that restrict individual freedoms? In this chapter, we examine human population dynamics worldwide, consider their causes, and assess their con- sequences for the environment and our society. ■

OUR WORLD AT SEVEN BILLION While China works to slow its population growth, numbers of people continue to rise in most nations. Most population growth is occurring in poverty-stricken developing nations that are ill-equipped to handle it. India ( FIGURE 6.1 ) is on course to surpass China as the world’s most populous nation in coming decades. Although the rate of human population growth is slowing, our absolute numbers are still increasing. Thus, our growth rate remains positive, and in 2011, our glo- bal population will surpass 7 billion.

FIGURE 6.1  Population growth is driving our global numbers to 7 billion and beyond. India is on course to overtake China and become the world’s most populous nation. In this photo, Indian women wait in line for immunizations for their babies.

The human population is growing rapidly Our global population grows by over 80 million people each year, a number equivalent to the combined populations of California, Texas, and New York. We add 2.6 people to the planet every second and could fill two large college football stadiums (capacity 110,000 each) with the number of humans added to the population every day. It took until after 1800, virtually all of human history, for our population to reach 1 billion. Yet we’ve added 6 billion people to the global popula- tion since then, with the last three installments of 1 billion people taking only 12 years each ( FIGURE 6.2 ) No previous generation has ever lived amid so many other people.

What accounts for our unprecedented growth? Exponential growth—the increase in a quantity by a fixed percentage per unit time—accelerates increase in population size over time, just as compound interest accrues in a savings account (p. 55 ). The rea- son, you will recall, is that a fixed percentage of a small number makes for a small increase, but that same percentage of a large number produces a large increase. Thus, even if the growth rate remains steady, population size will increase by greater incre- ments with each successive generation.

For much of the 20th century, the growth rate of the hu- man population rose from year to year. This rate peaked at 2.1% during the 1960s and has declined to 1.2% since then. Although 1.2% may sound small, exponential growth en- dows small numbers with large consequences. A hypothetical population starting with one man and one woman that grows at 1.2% gives rise to a population of 2,939 after only 40 gen- erations and 112,695 after 60 generations. Also, although the

FAQ

Q: How big is a billion?

A: Human beings have trouble conceptualizing huge numbers. As a result, we often fail to recognize the true magnitude of a number such as 7 billion. Although we know that a billion is bigger than a million, we tend to view both numbers as impossibly large and therefore similar in size. For example, guess (without calculating) how long it would take a banker to count out $1 million if she did it at a rate of a dollar a second for 8 hours a day, 7 days a week. Now guess how long it would take to count $1 billion at the same rate. The difference between your estimate and the answer may surprise you. Counting $1 million would take a mere 35 days, whereas counting $1 billion would take 95 years! Living 1 million seconds takes only 12 days, while living for 1 billion seconds requires more than 31 years. You couldn’t live for 7 billion seconds if you tried, because that would take 221 years. Examples like these can help us appreciate the “b” in “billion.”

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To help you visualize just how fast our world population has grown—and will continue to grow in your lifetime—take a look at the ENVISIONIT feature on p. 116. In other chapters you will similarly find an EnvisionIt page that uses visual images to bring to life important concepts in environmental science.

Is there a limit to human population growth? Our spectacular growth in numbers has resulted largely from technological innovations, improved sanitation, better medi- cal care, increased agricultural output, and other factors that have brought down death rates and infant mortality rates. Birth rates have not declined as much, so births have outpaced deaths for many years now, leading to population growth. But can the human population continue to grow indefinitely?

Environmental factors set limits on the growth of popu- lations (p. 58), but environmental scientists who have tried to pin a number to the human carrying capacity (p. 59) have come up with wildly differing estimates. The most rigorous estimates range from 1–2 billion people living prosperously in a healthy environment to 33 billion people living in extreme poverty in a degraded world of intensive cultivation without natural areas.

The difficulty in estimating the carrying capacity for hu- mans is that we are a particularly successful species, and we have repeatedly overcome predicted limits on growth by developing new technologies and ways of securing resources. For example, British economist Thomas Malthus (1766–1834) argued in his influential work An Essay on the Principle of Population (1798) that if society did not reduce its birth rate, then rising death rates would reduce the population through war, disease, and starva- tion. Although his contention was reasonable at the time, agricul- tural improvements in the 19th century increased food supplies, and his prediction did not come to pass. Similarly, biologist Paul Ehrlich predicted in his 1968 book The Population Bomb that human population growth would soon outpace food production

global growth rate is 1.2%, rates vary widely from region to region and are highest in developing nations (FIGURE 6.3).

At a 1.2% annual growth rate, a population doubles in size in only 58 years. We can roughly estimate doubling times with a handy rule of thumb. Just take the number 70 (which is 100 times 0.7, the natural logarithm of 2) and di- vide it by the annual percentage growth rate: 70/1.2 = 58.3. China’s current growth rate of 0.5% means it would take roughly 140 years (70/0.5 = 140) for its population to dou- ble. Had China not instituted its one-child policy and had its growth rate remained unchecked at 2.8%, it would have taken only 25 years (70/2.8 = 25) to double in size.

1750 1800 1850 Year

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FIGURE 6.2  Viewing global human population size over a long time scale (bottom graph) and since the industrial revolution (inset top graph) shows how nearly all growth has occurred in just the past 200 years. We have risen from fewer than 1 billion in 1800 to nearly 7 billion today. Data from U.S. Bureau of the Census.

Less than 0% (negative) 0 - 0.75% 0.75 - 1.50%

1.50 - 2.25% 2.25 - 3.00%

More than 3.00%

Population growth rate

FIGURE 6.3  Population growth rates vary greatly from place to place. Population is growing fastest in poorer nations of the tropics and subtropics but is now beginning to decrease in some northern industrialized nations. Shown are natural rates of population change (p. 122) as of 2010. Data from Population Reference Bureau, 2010. 2010 World population data sheet. By permission.

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You Can Make a Difference Support women’s rights and education in developing nations.

Even as population grows, reducing your resource consumption will lessen your ecological footprint.

1900 1950

2000 2050

For every two people alive in 2000, there will be three in 2050. Will enough natural resources remain to provide our children the standard of living we enjoy today?

Then our numbers exploded: In 2000 our population was 2.4 times greater than in 1950, an increase of 140%.

From 1900 to 1950 numbers grew by 50%. Earth has become more crowded as our global population has grown.

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population growth, the average person in the future will have less space in which to live, less food to eat, and less material wealth than the average person does today. Thus population growth is indeed a problem if it depletes resources, stresses social systems, and degrades the natural environment, such that our quality of life declines (FIGURE 6.4).

Population is one of several factors that affect the environment One widely used formula gives us a handy way to think about population and other factors that affect environmental qual- ity. Nicknamed the IPAT model, it is a variation of a formula proposed in 1974 by Paul Ehrlich and John Holdren. The IPAT model represents how our total impact (I) on the envi- ronment results from the interaction among population (P), aff luence (A), and technology (T):

I = P × A × T

Increased population intensifies impact on the environment as more individuals take up space, use natural resources, and gen-

and unleash massive famine and conflict in the latter 20th cen- tury. However, thanks to the way the “Green Revolution” (p. 136) increased food production in developing regions in the decades after his book, Ehrlich’s dire forecasts did not fully materialize.

Does this mean human innovation will always find a way to support our population? Under the view that many econo- mists hold, resource depletion due to population increase is not a problem if new resources can be found or created to re- place depleted ones (p. 91). In contrast, environmental scien- tists recognize that few resources are actually created by people and that not all resources can be replaced once they are deplet- ed. For example, once a species is extinct, we cannot replicate its exact function in an ecosystem. As the human population continues to climb, we may yet continue to find ways to raise our carrying capacity. But given our knowledge of population ecology and logistic growth (pp. 58–59), we have no reason to presume that human numbers can increase forever.

But is human population growth really a problem? Even if resource substitution could hypothetically enable our popu- lation to grow indefinitely, could we maintain the quality of life we desire for ourselves and our descendants? Unless the availability and quality of all resources keeps pace forever with

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New technologies

Better sanitation

Better medical care

More agricultural production

Decline in death rates

Birth rates remain high

Prohibitions on birth control

Restrictions on women’s rights

Historic need for farm labor

Habitat alteration

Solutions

As you progress through this chapter, try to identify as many solutions to human population growth as you can. What could you personally do to help address this issue? Consider how each action or solution might affect items in the concept map above.

Social disruption

Health impacts

Economic loss

War, conflict, refugees

Denser populations

Human population growth More fossil

fuel use

Loss of biodiversity and ecosystem

services

Global climate change

More waste and pollution

More resource extraction,

manufacturing, and consumption

More agricultural production

FIGURE 6.4  Human population growth has diverse causes (ovals on left) and consequences (boxes on right), as we shall see throughout this chapter. The consequences of rapid population growth are generally negative for society and the environment. Arrows in this concept map lead from causes to consequences. Note that items grouped within outlined boxes do not necessarily share any special relationship; the outlined boxes are merely to streamline the figure.

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Population size Our global human population of more than 7 billion is spread among over 200 nations with populations ranging up to China’s 1.34 billion, India’s 1.21 billion, and the 312 million of the United States (FIGURE 6.5). The United Nations Population Division estimates that by the year 2050, the global population will surpass 9 billion (FIGURE 6.6). However, popu- lation size alone—the absolute number of individuals—doesn’t tell the whole story. Rather, a population’s environmental impact depends on its density, distribution, and composition (as well as on affluence, technology, and other factors outlined earlier).

erate waste. Increased affluence magnifies environmental im- pact through the greater per capita resource consumption that generally has accompanied enhanced wealth. Technology that enhances our abilities to exploit minerals, fossil fuels, old-growth forests, or ocean fisheries generally increases impact, but tech- nology to reduce smokestack emissions, harness renewable en- ergy, or improve manufacturing efficiency can decrease impact.

We might also add a fourth factor, sensitivity (S), to the equation to denote how sensitive a given environment is to hu- man pressures. For instance, the arid lands of western China are more sensitive to human disturbance than the moist re- gions of southeastern China. Plants grow more slowly in the arid west, making the land more vulnerable to deforestation and soil degradation. Thus, adding an additional person to western China has more environmental impact than adding one to southeastern China. We could refine the IPAT equa- tion further by adding terms for the effects of social institu- tions such as education, laws and their enforcement, stable and cohesive societies, and ethical standards that promote environ- mental well-being. Such factors all affect how population, af- fluence, and technology translate into environmental impact.

Modern-day China shows how all elements of the IPAT for- mula can combine to cause tremendous environmental impact in little time. Although China boasts the world’s fastest growing economy, the country is battling unprecedented environmental challenges brought about by rapid economic development. In- tensive agriculture has expanded westward out of the country’s moist rice-growing areas, causing farmland to erode and blow away, much like the Dust Bowl tragedy that befell the U.S. heart- land in the 1930s (p. 141). China has overpumped aquifers and has drawn so much water for irrigation from the Yellow River that the once-mighty waterway now dries up in many stretches (p. 262). The nation now faces urban air pollution and massive traffic jams from rapidly rising numbers of automobiles. In Au- gust 2010, for example, a 100-km (60-mi) traffic jam formed on the outskirts of Beijing and persisted for more than 10 days! As the world’s developing countries try to attain the material pros- perity that industrialized nations enjoy, China is a window into what much of the rest of the world could soon become.

DEMOGRAPHY It is a fallacy to think of people as being somehow outside nature. We exist within our environment as one species out of many. As such, all the principles of population ecology that apply to toads, frogs, and passenger pigeons (Chapter 3) apply to humans as well. The application of principles from pop- ulation ecology to the study of statistical change in human populations is the focus of demography.

Demography is the study of human population Demographers study population size, density, distribution, age structure, sex ratio, and rates of birth, death, immigra- tion, and emigration of people, just as population ecologists study these characteristics in other organisms. Each of these characteristics is useful for predicting population dynamics and environmental impacts.

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India (1.207 billion)

China (1.345 billion)

United States (312 million)

Indonesia (239 million)

Brazil (195 miilion)

Pakistan (189 million)

Bangladesh (167 million)

Nigeria (162 million)

Russia (141 million)

Japan (127 million)

Mexico (112 million)

Other nations (2.779 billion)

FIGURE 6.5  Almost one in five people in the world is Chinese, and more than one of every six live in India. Three of every five people live in one of the 11 nations that have populations above 100 million. Data are projected for mid-2011, based on Population Refer- ence Bureau, 2010. 2010 world population data sheet.

20 00

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FIGURE 6.6  The United Nations predicts world population growth. In the latest projection (made in 2010), population is esti- mated to reach 11.0 billion in the year 2050 if fertility rates remain constant at 2005–2010 levels (top line in graph). However, U.N. demographers expect fertility rates to continue falling, so they arrived at a best guess (medium scenario) of 9.3 billion for 2050. In the high scenario, if women on average have 0.5 child more than in the medium scenario, population will reach 10.6 billion in 2050. In the low scenario, if women have 0.5 child fewer than in the medium scenario, the world will contain 8.1 billion people in 2050. Adapted by permission from Population Division of the Department of Economic and Social

Affairs of the United Nations Secretariat, 2011. World population prospects:

The 2010 revision, http://esa.un.org/unpp, Fig 1. © United Nations, 2011.

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lands, for instance, are easily degraded by agriculture and ranching that commandeers too much water.

Age structure Age structure describes the relative num- bers of individuals of each age class within a population (p. 54). These data are valuable for predicting future dynam- ics of human populations. A population made up mostly of individuals past reproductive age will tend to decline over time. In contrast, a population with many individuals of re- productive age or pre-reproductive age is likely to increase. A population with an even age distribution will likely remain stable as births keep pace with deaths.

Age structure diagrams, often called population pyra- mids, are visual tools scientists use to illustrate age structure (FIGURE 6.8). The width of each horizontal bar represents the number of people in each age class. A pyramid with a wide

0 Persons/km2

1 - 4 5 - 24

25 - 249 250 - 999

1,000+

FIGURE 6.7  Human population density varies tremendously from one region to another. Arctic and desert regions have the lowest population densities, whereas areas of India, Bangladesh, and eastern China have the densest populations. The World: Population Density, 2000. Center for International Earth Science Information Network (CIESIN), Columbia University; and Centro Internacional de Agricultura Tropical (CIAT). 2005. Gridded Population of the World Version 3

(GPWv3). Palisdes, NY: Socioeconomic Data and Applications Center (SEDAC), Columbia University. By permission.

Population density and distribution People are dis- tributed unevenly across our planet. In ecological terms, our distribution is clumped (pp. 54–55) at all spatial scales. At the global scale (FIGURE 6.7), population density is highest in regions with temperate, subtropical, and tropical climates and lowest in regions with extreme-climate biomes, such as desert, rainforest, and tundra. Human population is dense along seacoasts and rivers, and less dense away from water. At more local scales, we cluster together in cities and towns.

This uneven distribution means that certain areas bear more environmental impact than others. Just as the Yellow River experiences pressure from Chinese farmers, the world’s other major rivers all receive more than their share of hu- man impact. At the same time, some areas with low popula- tion density are sensitive (a high S value in our revised IPAT model) and thus vulnerable to impact. Deserts and arid grass-

A g e

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rs )

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Reproductive age

Pre- reproductive age

Number of males Number of females

Increasing rapidly Stable Decreasing

Number of males

Number of females

Number of males

Number of females

FIGURE 6.8  Age structure diagrams show numbers of individuals of different age classes in a population. A diagram like that on the left is weighted toward young age classes, indicating a population that will grow quickly. A diagram like that on the right is weighted toward old age classes, indicating a population that will decline. Popu- lations with balanced age structures, like the one shown in the middle diagram, will remain stable.

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Population change results from birth, death, immigration, and emigration Rates of birth, death, immigration, and emigration deter- mine whether a population grows, shrinks, or remains sta- ble. The formula for measuring population growth (p. 55)

China’s Reproductive Policy Consider the benefits as well as the problems associated with a reproductive policy such as China’s. Do you think a government should be able to enforce strict

penalties for citizens who fail to abide by such a policy? If you disagree with China’s policy, what alternatives can you suggest for dealing with the resource demands of a rapidly growing population?

In recent years, demographers have witnessed an unset- tling trend in China: The ratio of newborn boys to girls has become strongly skewed. In the 2000 census, 120 boys were reported born for every 100 girls. Some provinces reported sex ratios as high as 138 boys for every 100 girls. The leading hypothesis for these unusual sex ratios is that some parents, having learned the gender of their fetuses by ultrasound, are selectively aborting female fetuses.

China’s skewed sex ratio may further lower population growth rates. However, it has proved tragic for the “missing girls.” It is also having the undesirable social consequence of leaving many Chinese men single. This, in turn, has resulted in a grim new phenomenon. In parts of rural China, teenaged girls are being kidnapped and sold to families in other parts of the country as brides for single men.

base denotes a large proportion of people who have not yet reached reproductive age—and this indicates a population soon capable of rapid growth.

As an example, compare age structures for Canada and Madagascar (FIGURE 6.9). Madagascar’s large concentration of individuals in young age groups portends a great deal of re- production. Not surprisingly, Madagascar has a much greater population growth rate than Canada.

Today, populations are aging in many nations, including the United States. The global median age today is 28, but it will be 38 in the year 2050. China’s population policies have radically changed its age structure. In 1970 the median age in China was 20; by 2050 it will be 45. In 1970, China had more children under age 5 than people over 60, but by 2050 there will be 12 times more people over 60 than under age 5! This dramatic shift in age structure (FIGURE 6.10) will challenge China’s economy, health care system, families, and military forces because fewer working-age people will be available to support social programs to assist the rising number of older people. However, a changing age structure may also lead to increased benefits to society from volunteer efforts by pro- ductive retirees. In many ways both good and bad, “graying” populations will affect societies in China, the United States, and elsewhere throughout our lifetimes.

Sex ratios The ratio of males to females also can affect pop- ulation dynamics. The naturally occurring sex ratio at birth in human populations features a slight preponderance of males; for every 100 female infants born, about 106 male infants are born. This phenomenon is an evolutionary adaptation to the fact that males are slightly more prone to death during any giv- en year of life. It tends to ensure that the ratio of men to women will be approximately equal when people reach reproductive age. Thus, a slightly uneven sex ratio at birth may be beneficial. However, a greatly distorted ratio can lead to problems.

Male Female Male Female

100

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0 1 212 2 1 0 1 2

(b) Age pyramid of Madagascar in 2010(a) Age pyramid of Canada in 2010

FIGURE 6.9 Canada (a) shows a fairly balanced age structure, with relatively even numbers of individuals in vari- ous age classes. Madagascar (b) shows an age distribution heavily weighted toward young people. Madagascar’s population growth rate (2.9%) is over seven times greater than Canada’s (0.4%). Data from Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, 2011. World population prospects: The 2010 revision,

http://esa.un.org/unpp. © United Nations, 2011. By permission.

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(b) Projected age pyramid of China in 2050

(d) Elderly Chinese(c) Young female factory workers in Hong Kong

(a) Age pyramid of China in 2010

Population (millions)

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A g

e 90

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FIGURE 6.10  As China’s population ages, older people will outnumber the young. Population pyramids show the predicted graying of the Chinese population from 2010 (a) to 2050 (b). Today’s children may, as working-age adults (c), face pressures to support greater numbers of elderly citizens (d) than has any previous generation. Data in (a) and (b) from Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, 2011. World

population prospects: The 2010 revision, http://esa.un.org/unpp. © United Nations, 2011. By permission.

size of a population stable. For humans, replacement fertil- ity roughly equals a TFR of 2.1. (Two children replace the mother and father, and the extra 0.1 accounts for the risk of a child dying before reaching reproductive age.) If the TFR drops below 2.1, population size (in the absence of immigra- tion) will shrink.

Various factors have driven TFR downward in many nations in recent years. Historically, people tended to conceive many children, which helped ensure that at least some would survive. Today’s improved medical care has reduced infant mor- tality rates, making it less necessary to bear multiple children. Urbanization has also driven TFR down; whereas rural families need children to contribute to farm labor, in urban areas chil- dren are usually excluded from the labor market, are required to go to school, and impose economic costs on their families. Moreover, if a government provides some form of social securi- ty, as most do these days, parents need fewer children to support them in their old age. Finally, with greater educational opportu- nities and changing roles in society, women tend to shift into the labor force, putting less emphasis on child rearing.

pertains to people: Birth and immigration add individuals to a population, whereas death and emigration remove indi- viduals. Technological advances during the last 200 years led to a dramatic decline in human death rates, widening the gap between birth rates and death rates and resulting in the glo- bal human population expansion.

In recent decades, reductions in birth rates around the world have led to an overall decline in the global growth rate (FIGURE 6.11). Note, however, that although the rate of growth is slowing, the absolute size of the population continues to increase. Even though our growth rate is getting smaller year by year, we con- tinue to add over 80 million people to the planet each year.

Total fertility rate influences population growth One key statistic demographers calculate to examine a popu- lation’s potential for growth is the total fertility rate (TFR), the average number of children born per woman during her lifetime. Replacement fertility is the TFR that keeps the

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undergone urbanization and industrialization and have gen- erated personal wealth for their citizens.

To make sense of these trends, demographers developed a concept called the demographic transition. This is a model of economic and cultural change first proposed in the 1940s and 1950s by demographer Frank Notestein to explain the de- clining death rates and birth rates that have occurred in West- ern nations as they industrialized. Notestein believed nations move from a stable pre-industrial state of high birth and death rates to a stable post-industrial state of low birth and death rates (FIGURE 6.12). Industrialization, he proposed, causes these rates to fall by first decreasing mortality and then lessen- ing the need for large families. Parents thereafter choose to in- vest in quality of life rather than quantity of children. Because death rates fall before birth rates fall, a period of net popula- tion growth results. Thus, under the demographic transition model, population growth is seen as a temporary phenomenon that occurs as societies move from one stage of development to another.

The pre-industrial stage The first stage of the demo- graphic transition model is the pre-industrial stage, charac- terized by conditions that have defined most of human his- tory. In pre-industrial societies, death rates and birth rates are both high. Death rates are high because disease is wide- spread, medical care rudimentary, and food supplies unreli- able and difficult to obtain. Birth rates are high because peo- ple must compensate for infant mortality by having several children. In this stage, children are valuable as workers who can help meet a family’s basic needs. Populations within the pre-industrial stage are not likely to experience much growth, which is why the human population was relatively stable until the industrial revolution.

Industrialization and falling death rates Industriali- zation initiates the second stage of the demographic transi- tion, known as the transitional stage. This transition from the pre-industrial stage to the industrial stage is generally characterized by declining death rates due to increased food production and improved medical care. Birth rates in the transitional stage remain high, however, because people have not yet grown used to the new economic and social condi- tions. As a result, population growth surges.

All these factors have come together in Europe, where TFR has dropped from 2.6 to 1.6 in the past half-century. Nearly every European nation now has a fertility rate below the replacement level, and populations are declining in 17 of 45 European nations. In 2010, Europe’s overall annual natural rate of population change (change due to birth and death rates alone, excluding migration) was between 0.0% and 0.1%. Worldwide by 2010, 72 countries had fallen below the replace- ment fertility of 2.1. These countries make up roughly 45% of the world’s population and include China (with a TFR of 1.5). TABLE 6.1 shows TFRs of major continental regions.

Many nations have experienced the demographic transition Many nations with lowered birth rates and TFRs are expe- riencing a common set of interrelated changes. In countries with good sanitation, effective health care, and reliable food supplies, more people than ever before are living long lives. As a result, over the past 50 years the life expectancy (the time a person can expect to live) for the average person worldwide has increased from 46 to 69 years, with much of this increase attributed to reductions in infant mortality rates. Societies going through these changes are generally those that have

World

Least developed countries

More developed regions Less developed regions

Global population

0.5

0.0

–0.5

1.0

1.5

2.0

3.0

2.5

1950 1960 1970 1980 1990 2000 2010

Po p

u la

ti o

n g

ro w

th r

at e

(p er

ce n

G lo

b al

p o

p u

la ti o

n ( b

ill io

n s

o f

p eo

p le

) Year

FIGURE 6.11  The annual growth rate of the global human popu- lation (dark blue line) peaked in the late 1960s and has declined since then. Growth rates of developed regions (green line) have fallen since 1950, while those of developing regions (red line) have fallen since the global peak in the late 1960s. For the world’s least developed countries (orange line), growth rates began to fall in the 1990s. Although growth rates are declining, global population size (gray bars) is still growing about the same amount each year, because smaller percentage increases of ever-larger numbers produce roughly equivalent additional amounts. Data from Population Division of the Department of Economic and Social Affairs of the United Na-

tions Secretariat, 2011. World population prospects: The 2010 revision, http://

esa.un.org/unpp. © United Nations, 2011. By permission.

TABLE 6.1 Total Fertility Rates for Major Regions Region

Total fertility rate (TFR)

Africa 4.7

Australia and the South Pacific 2.5

Latin America and the Caribbean 2.3

Asia 2.2

North America 2.0

Europe 1.6 Data from Population Reference Bureau, 2010. 2010 World population data sheet.

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everyone lived like a modern American. Thus, whether devel- oping nations (which include the vast majority of the planet’s people) pass through the demographic transition is one of the most important questions for the future of our civilization and Earth’s environment.

POPULATION AND SOCIETY Demographic transition theory links the quantitative study of how populations change with the societal factors that in- f luence (and are inf luenced by) population dynamics. Let’s examine a few of these societal factors more closely.

Family planning is a key approach for controlling population growth Perhaps the greatest single factor enabling a society to slow its population growth is the ability of women and couples to engage in family planning, the effort to plan the number and spacing of one’s children. Family-planning programs and clinics offer information and counseling to potential moth- ers and fathers on reproductive issues. An important compo- nent of family planning is birth control, the effort to control the number of children one bears, particularly by reducing the frequency of pregnancy. This relies on contraception, the deliberate attempt to prevent pregnancy despite sexual inter- course. Common methods of modern contraception in use today include condoms, spermicide, hormonal treatments (birth control pill/hormone injection), intrauterine devices (IUDs), and permanent sterilization through tubal ligation or vasectomy. Many family-planning organizations aid clients by offering free or discounted contraceptives.

Worldwide in 2010, 55% of women (aged 15–49) re- ported using contraceptives, with rates of use varying widely among nations. China, at 86%, had the highest rate of con- traceptive use of any nation. Six European nations showed rates of contraceptive use of 70% or more, as did Australia,

The industrial stage and falling birth rates The third stage in the demographic transition is the industrial stage. Industrialization increases opportunities for employ- ment outside the home, particularly for women. Children be- come less valuable, in economic terms, because they do not help meet family food needs as they did in the pre-industrial stage. If couples are aware of this, and if they have access to birth control, they may choose to have fewer children. Birth rates fall, closing the gap with death rates and reducing popu- lation growth.

The post-industrial stage In the final stage, the postindustrial stage, both birth and death rates have fallen to low and stable levels. Population sizes stabilize or decline slightly. The society enjoys the fruits of industrialization without the threat of runaway population growth.

Is the demographic transition a universal process? The demographic transition has occurred in many Euro- pean countries, the United States, Canada, Japan, and sev- eral other developed nations over the past 200 to 300 years. It is a model that may or may not apply to all developing nations as they industrialize now and in the future. On the one hand, note in Figure 6.12 how growth rates fell first for industrialized nations, then for less developed nations, and finally for least developed nations, suggesting that it may merely be a matter of time before all nations experi- ence the transition. On the other hand, some developing nations may already be suffering too much from the im- pacts of large populations to replicate the developed world’s transition. Cultures that place greater value on childbirth or grant women fewer freedoms may never complete the transition.

Moreover, natural scientists estimate that we would need the natural resources of four-and-a-half planet Earths if

Time

Population increase

G ro

w th

r a

Birth rate and death rate are high

Birth rate and death rate are low

Pre-industrial stage

Post-industrial stage

Industrial stage

Transitional stage

Death rate declines due to increased food production and improved medical care

D eath rate

Birth rate

Birth rate declines due to increased opportunities for women and access to birth control

FIGURE 6.12  The demographic transition models a process that has taken some populations from a pre-industrial stage of high bir th rates and high death rates to a post-industrial stage of low bir th rates and low death rates. In this diagram, the wide green area between the two cur ves illustrates the gap between bir th and death rates that causes rapid population growth during the middle por tion of this process. Adapted from Kent, M., and K. Crews, 1990. World population:

Fundamentals of growth. By permission of

the Population Reference Bureau.

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In a physiological sense, access to family planning and im- proved rights gives women control over their reproductive window, the period of their life, beginning with sexual maturity and ending with menopause, in which they may become pregnant. A woman can bear up to 25 children within this window (FIGURE 6.14A), but she may choose to delay the birth of her first child to pursue education and employment. She may also use contraception to delay her first child, space births within the window, and “close” her reproductive window after achieving her desired family size (FIGURE 6.14B).

Population policies and family-planning programs are working around the globe Data show that funding and policies that encourage family planning can lower population growth rates in all types of nations, even those that are least industrialized. No nation has pursued a sustained population control program as intru- sive as China’s, but other rapidly growing nations have imple- mented less restrictive programs.

India was the first nation to implement population control policies. However, when some policymakers intro- duced forced sterilization in the 1970s, the resulting outcry brought down the government. Since then, India’s efforts have been more modest and far less coercive, focusing on family planning and reproductive health care. However, today a number of Indian states also run programs of in- centives and disincentives promoting a “two-child norm,” and current debate centers on whether this is a just and effective approach.

The government of Thailand has reduced birth rates and slowed population growth. In the 1960s, Thailand’s growth rate was 2.3%, but today it stands at 0.6%. This decline was achieved without a one-child policy, resulting instead from an education-based approach to family plan- ning and the increased availability of contraceptives. Brazil, Mexico, Iran, Cuba, and many other developing countries have instituted active programs to reduce their population growth that entail setting targets and providing incentives, education, contraception, and reproductive health care. These programs are working: Studies show that nations with such programs have lower fertility rates than similar nations without them (FIGURE 6.15).

In 1994, the United Nations hosted a milestone con- ference on population and development in Cairo, Egypt, at which 179 nations endorsed a platform calling on all gov- ernments to offer their citizens universal access to reproduc- tive health care within 20 years. The conference marked a turn away from older notions of top-down population policy geared toward pushing contraception and lowering popula- tion to preset targets. Instead, it urged governments to offer better education and health care and to address social needs that affect population from the bottom up (such as allevi- ating poverty, disease, and sexism). However, worldwide funding for family planning fell by more than one-third in the decade following the Cairo conference, slowing progress on these initiatives.

Brazil, Canada, Costa Rica, Cuba, Micronesia, New Zealand, Nicaragua, Paraguay, Puerto Rico, Thailand, the United States, and Uruguay. At the other end of the spectrum, 17 African nations had rates below 10%.

Low usage rates for contraceptives in some societies are due to religious doctrine or cultural influences that hinder family planning, denying counseling and contraceptives to people who might otherwise use them. This can result in fam- ily sizes that are larger than the parents desire and to elevated rates of population growth.

Empowering women reduces fertility rates Today, many social scientists and policymakers recognize that for population growth to slow and stabilize, women should be granted equal power to men in societies worldwide. This would have many benefits: Studies show that where women are freer to decide whether and when to have children, fertil- ity rates fall, and the resulting children are better cared for, healthier, and better educated.

One benefit of equal rights for women is the ability to make reproductive decisions. In many societies, men restrict women’s decision-making abilities, including decisions as to how many children they will bear. Fertility rates have dropped most noticeably in nations where women have gained im- proved access to contraceptives and to family planning (see THE SCIENCE BEHIND THE STORY, pp. 128–129).

Equality for women also involves expanding educational opportunities for them, because in many nations girls are dis- couraged from pursuing an education or kept out of school altogether. Over two-thirds of the world’s people who cannot read are women. And data clearly show that as women receive educational opportunities, fertility rates decline (FIGURE 6.13). Education helps more women pursue careers, delay childbirth, and have a greater say in reproductive decisions.

0 0

10 20 30

To ta

l f er

ti lit

y ra

te (

1 9 9 5 –2

0 0

0 )

40 50 60 70 80 90 100

Female secondary school enrollment rate (%)

India

Vietnam Colombia Peru

Jamaica

EgyptSyria Kenya

GuatemalaCambodia

Ethiopia

South Africa

FIGURE 6.13  Increasing female literacy is strongly associated with reduced birth rates in many nations. Data from McDonald, M., and D. Nierenberg, 2003. Linking population, women, and biodiversity. State of

the world 2003. Washington, D.C.: Worldwatch Institute.

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Birth

(a) Potential fertility

(b) Fertility reductions by delaying childbirth and contraceptive use

10 years 20 years

Reproductive window

30 years 40 years 50 years 60 years

Birth 10 years 20 years

Delaying childbirth to focus on education and career

Spacing births with contraception Ending reproductive

potential with contraception

30 years 40 years 50 years 60 years

First menstrual cycle

Last menstrual cycle (menopause)

First menstrual cycle

Last menstrual cycle (menopause)

FIGURE 6.14  (a) Women can potentially have very high fertility within their “reproductive window” but (b) can reduce the number of births by delaying the birth of their first child to pursue education and career and by using contraception to space pregnancies or to end their reproductive window at the time of their choosing.

1960 1970 1980 1990 2000

To ta

l f er

ti lit

y ra

1960 1970 1980 1990 2000

To ta

l f er

ti lit

y ra

1960 1970 1980 1990 2000

To ta

l f er

ti lit

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1960 1970 1980 1990 2000 2010 2010

2010 2010

To ta

l f er

ti lit

y ra

Iraq Pakistan

Bangladesh

Haiti

Dominican Republic

Iran

Malawi

Kenya

FIGURE 6.15  Data from four pairs of neighboring countries demonstrate the effectiveness of family planning in reducing fertility rates. In each case, the nation that invested in family planning and (in some cases) made other reproductive rights, educa- tion, and health care more available to women (blue lines) reduced its total fertility rate (TFR) more than its neighbor (red lines). Data from Popula- tion Reference Bureau and Harrison, P., and

F. Pearce, 2000. AAAS Atlas of population

and environment, edited by the American

Association for the Advancement of Sci-

for the Advancement of Science. Used by

permission of the publisher, University of

California Press.

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0.0 $0

$50,000

$45,000

$40,000

$35,000

$30,000

$25,000

$20,000

$15,000

$10,000

$5,000

0.5

Pe r-

ca p

it a

in co

m e

(G N

I- PP

P1 )

1.0 1.5 2.52.0

Population growth rate

Africa

North America

Latin America and Caribbean

Asia

Europe

Australia and S. Pacific

FIGURE 6.16  Poverty and population growth show a fairly strong correlation, despite the influence of many other factors. Re- gions with the most rapid population growth tend to show lower per capita incomes. Per capita income is here measured in GNI PPP, or “gross national income in purchasing power parity,” a measure that standard-

izes income among nations by converting it to “international” dollars, which

indicate the amount of goods and services one could buy in the United States

with a given amount of money. Data from Population Reference Bureau, 2010.

2010 World population data sheet.

Year

G lo

b al

p o p u la

ti o n ( b ill

io n s)

1950 1975

0 2000 2025 2050

Developing countries Developed countries

FIGURE 6.17  Over 99% of the next 1 billion people added to Earth’s population will be born into the less developed, poorer parts of the world. Dashed portions of the lines indicate projected future trends. Data from Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, 2011. World population

prospects: The 2010 revision, http://esa.un.org/unpp. © United Nations, 2011.

By permission.

Should the United States Abstain from International Family Planning? Over the years, the United States has joined 180 other nations in providing millions of dollars to the

United Nations Population Fund (UNFPA), which advises governments on family planning, sustainable develop- ment, poverty reduction, reproductive health, and AIDS prevention in many nations, including China. Starting in 2001, the Bush administration withheld funds, saying that U.S. law prohibits funding any organization that “sup- ports or participates in the management of a program of coercive abortion or involuntary sterilization” and claim- ing that the Chinese government has been implicated in both. Many nations criticized the U.S. decision, and the European Union offered UNFPA additional funding to off- set the loss of U.S. contributions. Once President Obama came to office, he reinstated funding, asking Congress to allocate $60 million in 2009. What do you think U.S. policy should be? Should the United States fund family-planning efforts in other nations? What conditions, if any, should it place on the use of such funds?

Reducing poverty lowers fertility Over half the world’s people live below the internationally defined poverty line of U.S. $2 per day. The alleviation of poverty was a prime target of the Cairo conference because poorer societies tend to show higher population growth rates than do wealthier societies (FIGURE 6.16). This relationship

operates in both directions: Poverty exacerbates population growth, and rapid population growth worsens poverty.

These trends also influence the distribution of people on the planet. In 1960, 70% of the world’s population lived in de- veloping nations. As of 2010, 82% of all people live in these countries. Moreover, fully 99% of the next billion people to be added to the global population will be born into these poor, less developed regions (FIGURE 6.17).

This is unfortunate from a social standpoint, because these people will be added to the nations that are least able to provide for them. It is also unfortunate from an environmen- tal standpoint, because poverty often results in environmental degradation. People who depend on agriculture in areas of poor farmland, for instance, may need to try to farm even if doing so degrades the soil and is not sustainable. Poverty also drives people to cut forests and to deplete biodiversity. For ex- ample, impoverished settlers and miners hunt large mammals for “bush meat” in Africa’s forests, including the great apes that are now heading toward extinction.

Expanding wealth increases the environmental impact per person Poverty can lead people into environmentally destructive behavior, but wealth can produce even more severe and far-reaching environmental impacts. The aff luence of a so- ciety such as the United States, Japan, or the Netherlands is built on levels of resource consumption unprecedented in human history. Consider that the richest one-fifth of the world’s people possess over 80 times the income of the poorest one-fifth and use 86% of the world’s resources (FIG- URE 6.18). The environmental impact of human activities depends not only on the number of people involved but also on the way those people live (recall the A for aff luence in the IPAT equation).

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Average per U.S. resident: • $46,970 annual income • 31,000 m2 of land • 19.0 metric tons of CO2 emitted per year

Average per resident of India: • $2,960 annual income • 2,800 m2 of land • 1.1 metric tons of CO2 emitted per year

(a) A family living in the United States

(b) A family living in India

FIGURE 6.18  A typical U.S. family (a) may own a large house with a wealth of material possessions. A typical family in a developing nation such as India (b) may live in a small, sparsely furnished dwelling with few mate- rial possessions and little money or time for luxuries. Compared with the average resident of India, the average U.S. resident enjoys 16 times more income, uses 11 times more land, and emits 17 times more carbon dioxide emissions. Data from Population Refer- ence Bureau, 2009. 2009 World Population Data

Sheet.

We previously explored the concept of the ecological footprint, the cumulative amount of Earth’s surface area re- quired to provide the raw materials a person or population consumes and to dispose of or recycle the waste produced (pp. 4, 16). Individuals from affluent societies leave consider- ably larger per capita ecological footprints (see Figure 1.16, p. 16). In this sense, the addition of one American to the world has as much environmental impact as the addition of 3.5 Chi- nese, 9 Indians, or 13 Afghans. This fact reminds us that the “population problem” does not lie solely with the developing world!

Indeed, just as population is rising, so is consumption. We have seen that humanity’s global ecological footprint sur- passed Earth’s capacity to support us in 1970s (p. 4) and our

species is now living 50% beyond its means (FIGURE 6.19). The rising consumption that is accompanying the rapid industri- alization of China, India, and other populous nations makes it all the more urgent for us to find this path to global sustain- ability.

If humanity’s overarching goal is to generate a high standard of living and quality of life for all people, then devel- oping nations must find ways to slow their population growth. However, those of us living in the developed world must also be willing to reduce our consumption. Earth does not hold enough resources to sustain all 7 billion of us at the current North American standard of living, nor can we venture out and bring home extra planets. We must make the best of the one place that supports us all.

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T H

E S

C IE

N C

E B

E H

IN D

T H

E S

T O

R Y

Dr. James Phillips of Columbia University

Bangladesh is one of the poorest and most densely populated countries on the planet. Its 166 million people live in an area about the size of Wis- consin, and 45% of them live below the poverty line. With few natural resources and 1,150 people per km2 (nearly 3,000 per mi2—2.5 times the population density of New Jersey), limiting population growth is critically important. Back in 1976, Bangladeshi president Ziaur Rahman declared, “If we cannot do something about popu- lation, nothing else that we accomplish will matter much.”

Since then, Bangladesh has made striking progress in slowing its popula- tion growth. Despite stagnant eco- nomic development, low literacy rates, poor health care, and limited rights for women, the nation’s total fertility rate (TFR) has dropped markedly. In the 1970s, the average woman in Bang- ladesh gave birth to nearly 7 children over the course of her life. Today, the TFR is 2.4 (see first figure).

Researchers hypothesized that family-planning programs were responsible for Bangla- desh’s rapid reduction in TFR. Because conducting an experi- ment to test such a hypothesis is difficult, some researchers took advantage of a natural experi- ment (pp. 9–10). By comparing Bangladesh to countries that are socioeconomically similar but have had less success in lower- ing TFR, such as Pakistan (see Figure 6.15, p. 125), researchers concluded that Bangladesh suc- ceeded because of aggressive, well-funded outreach efforts that were sensitive to the values of its traditional society.

However, no two nations are identical, so it is difficult to draw firm conclusions from such broad-scale comparisons. This is why the Matlab Family Planning and Health Services Project, in the iso- lated rural area of Matlab, Bangladesh,

has become one of the best-known experiments in family planning in de- veloping countries.

T H E S C I E N CE B E H I N D T H E S TO RY

Fertility Decline in Bangladesh

Research in developing nations indicates that poverty and overpopulation can create a vicious cycle, in which poverty promotes high fertility and high fertility obstructs economic development. Are there policy steps that such countries can take to bring down fertility rates? Scientific analy- sis of family-planning programs in the South Asian nation of Bangladesh suggests that there are.

1950 1960 1970 19901980 2000 To

ta l f

er ti lit

y ra

te , B

an g

la d

es h

2010

Year

Total fertility rate has declined markedly in Bangladesh in the past 40 years, in part because of family-planning programs. Data from Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, 2011. World population prospects: The 2010 revision, http://esa.un.org/unpp. © United Nations, 2011. By permission.

Ecological footprint Projected ecological footprint Biocapacity

Overshoot Path to

sustainability

Business as usual

Ecological reserve

Ecological debt

0.5

1.0

1.5

2.0

1960 1980 2000 2020 2040 2060 2080 2100

N u m

b er

o f

p la

n et

E ar

th s

Year

2.5

FIGURE 6.19  The global ecological footprint of the human population is estimated to be 50% greater than what Earth can bear in the long run. If population and consumption continue to rise (orange dashed line), we will increase our ecological deficit, or degree of overshoot, until systems give out and populations crash. If, instead, we pursue a path to sustainability (red dashed line), we can eventually repay our ecological debt and sustain our civiliza- tion. Adapted from WWF International, 2010. Living Planet Report 2010. Published by WWF-World Wide Fund for Nature. © 2010 WWF (panda.org).

Zoological Society of London, and Global Footprint Network.

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➤ CONCLUSION

The Matlab Project was an inten- sive outreach program run collabora- tively by the Bangladeshi government and international aid organizations. Each household in the project area received biweekly visits from local women offering counseling, educa- tion, and free contraceptives. Com- pared to a similar government-run program in a nearby area, the Matlab Project featured more training, more services, and more frequent visits. In both areas, a highly organized data collection system gave researchers detailed information about births, deaths, and health-related behaviors such as contraceptive use. The result was an experiment comparing the Matlab Project with the government- run project.

When Matlab Project director James Phillips and his colleagues reviewed a decade’s worth of data in 1988, they found that fertility rates had declined in both areas. The decline appeared to be due almost entirely to a rise in contraceptive use, because other factors—such as the aver- age age of marriage—remained the same. Phillips and his colleagues also found the declines to be significantly greater in the Matlab area than in the government-run area. These findings suggested that high-intensity outreach efforts could affect TFR even in the absence of significant improvements in women’s status, education, or econom- ic development.

Why was the outreach program successful? One hypothesis was that visits from health care workers helped

convince local women that small fami- lies are desirable. However, in 1999, Mary Arends-Kuenning, a University of Michigan graduate student, and her colleagues reported that there was no relationship between the number of visits made by outreach workers and women’s perception of the ideal family size, either in Matlab or nearby areas. Ideal family size declined equally in all areas. Instead of creating new demand for birth control, the Matlab Project ap- pears to have helped women convert an already-existing desire for fewer children into behaviors, such as contra- ceptive use, that reduce fertility.

Bangladesh’s ability to rein in fertility rates despite unfavorable social and economic conditions bodes well for impoverished nations facing explosive population growth. However, further reductions may require politi- cal and socioeconomic changes that are difficult to implement in traditional, resource-strapped countries such as Bangladesh. Nonetheless, scientific re- search from Matlab has illuminated the impacts of family-planning programs on fertility, helping to inform popula- tion control efforts in Bangladesh and elsewhere.

In the Matlab Project, Bangladeshi households received visits from local women offering counseling, education, and free contraceptives.

Today’s human population is larger than at any time in the past. Our growing population and our growing consumption affect the environment and our ability to meet the needs of all the world’s people. The great majority of children born today are likely to live their lives in conditions far less healthy and prosperous than most of us in the industrialized world are accustomed to.

However, there are at least two major reasons to be en- couraged. First, although global population is still rising, the rate of growth has decreased nearly everywhere, and some countries are even seeing population declines. Most developed nations have passed through the demographic transition, showing that it is possible to lower death rates while stabilizing population and creating more prosperous

societies. Second, progress has been made in expanding rights for women worldwide. Although there is still a long way to go, women are obtaining better education, more eco- nomic independence, and more ability to control their re- productive decisions. Aside from the clear ethical progress these developments entail, they are helping to slow popula- tion growth.

Human population cannot continue to rise forever. The question is how it will stop rising: Will it be through the gentle and benign process of the demographic transition, through restrictive governmental intervention such as China’s one- child policy, or through the miserable Malthusian checks of disease and social conf lict caused by overcrowding and competition for scarce resources? Moreover, sustainability

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C A L C U L A T I N G E C O L O G I C A L F O O T P R I N T S

A nation’s population size and the affluence of its citizens each influence its resource consumption and environmental impact. As of 2010, the world’s population passed 6.9 billion, and average per capita income was $10,030 per year, and the

latest estimate for the world’s average ecological footprint was 2.7 hectares (ha) per person. The sampling of data in the table will allow you to explore patterns in how population, affluence, and environmental impact are related.

1. China’s reduction in birth rates is leading to significant change in the nation’s age structure. Review Figure 6.10, which shows that the population is growing older, lead- ing to the top-heavy population pyramid for the year 2050. What effects might this ultimately have on Chinese society? What steps could be taken in response?

2. Apply the IPAT model to the example of China provided in the chapter. How do population, affluence, technology, and ecological sensitivity affect China’s environment? Now consider your own country or your own state. How do population, affluence, technology, and ecological sensitiv- ity affect your environment? How can we minimize the en- vironmental impacts of growth in the human population?

3. Do you think that all of today’s developing nations will complete the demographic transition and come to enjoy a permanent state of low birth and death rates? Why or why not? What steps might we as a global society take

to help ensure that they do? Now think about developed nations such as the United States and Canada. Do you think these nations will continue to lower and stabilize their birth and death rates in a state of prosperity? What factors might affect whether they do so?

4. THINK IT THROUGH India’s prime minister puts you in charge of that nation’s population policy. India has a population growth rate of 1.6% per year, a TFR of 2.7, a 49% rate of contraceptive use, and a population that is 71% rural. What policy steps would you recommend, and why?

5. THINK IT THROUGH Now suppose that you have been tapped to design population policy for Germany. Germany is losing population at an annual rate of 0.2%, has a TFR of 1.3, a 66% rate of contraceptive use, and a population that is 73% urban. What policy steps would you recommend, and why?

S E E K I N G S O L U T I O N S

1. What is the approximate current human global popula- tion? How many people are being added to the popula- tion each day?

2. Why has the human population continued to grow despite environmental limitations? Give one example of an inno- vation that increased the carrying capacity for humans.

3. Contrast the views of environmental scientists with those of economists and policymakers regarding whether pop- ulation growth is a problem. Name several reasons why population growth is commonly viewed as a problem.

4. Explain the IPAT model. How can technology either increase or decrease environmental impact? Provide at least two examples.

5. Describe how demographers use size, density, distribu- tion, age structure, and sex ratio of a population to esti- mate how it may change. How does each of these factors help determine the impact of human populations on the environment?

6. What is the total fertility rate (TFR)? Why is the re- placement fertility for humans approximately 2.1? How is Europe’s TFR affecting its natural rate of population change?

7. Why have fertility rates fallen in many countries? 8. How does the demographic transition model explain the

increase in population growth rates in recent centuries? How does it explain the recent decrease in population growth rates in many countries?

9. Why are the empowerment of women and the pursuit of gender equality viewed as important to controlling population growth? Describe the aim of family-planning programs.

10. Why do poorer societies have higher population growth rates than wealthier societies? How does poverty af- fect the environment? How does aff luence affect the environment?

T E S T I N G Y O U R C O M P R E H E N S I O N

demands a further challenge—that we stabilize our popula- tion size in time to avoid destroying the natural systems that support our economies and societies. We are indeed a special species. We are the only one to achieve the dominance to alter

much of Earth’s landscape and even its climate system. We are also the only species with the intelligence needed to halt the increase in our own numbers before we destroy the very systems on which we depend.

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1. Calculate the total impact (national ecological footprint) for each country.

2. Draw a graph illustrating per capita impact (on the y axis) versus aff luence (on the x axis). What do the results show? Explain why the data look the way they do.

3. Draw a graph illustrating total impact (on the y axis) in relation to population (on the x axis). What do the results suggest to you?

4. Draw a graph illustrating total impact (on the y axis) in relation to aff luence (on the x axis). What do the results suggest to you?

5. You have just used three of the four variables in the IPAT equation. Now give one example of how the T (technology) variable could potentially increase the total impact of the United States, and one example of how it could poten- tially decrease the U.S. impact.

Nation

Population (millions of people)

Affluence (per capita income, in GNI PPP)1

Personal impact (per capita footprint, in ha/person)

Total impact (national foot- print, in millions of ha)

Belgium 10.8 $34,760 8.0 86 Brazil 193.3 $10,070 2.9 China 1,338.1 $6,020 2.2 Ethiopia 85.0 $870 1.1 India 1,188.8 $2,960 0.9 Japan 127.4 $35,220 4.7 Mexico 110.6 $14,270 3.0 Russia 141.9 $15,630 4.4 United States 309.6 $46,970 8.0 2,477

1GNI PPP is “gross national income in purchasing power parity,” a measure that standardizes income among nations by converting it to “ international” dollars, which indicate the amount of goods and services one could buy in the United States with a given amount of money.

Data Sources: Population and aff luence data are from Population Reference Bureau, 2010. World population data sheet 2010. Footprint data are for 2007, from WWF International, Zoological Society of London, and Global Footprint Network. Living Planet Report 2010.

Go to www.masteringenvironmentalscience.com for homework assignments, practice quizzes, Pearson eText, and more.

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Soil, Agriculture, and the Future of Food Upon completing this chapter, you will be able to:

➤ Explain the challenges of feeding a growing human population ➤ Compare and contrast traditional, industrial, and sustainable agricultural approaches ➤ Identify the goals, methods, and consequences of the Green Revolution ➤ Explain the importance of soils to agriculture ➤ Analyze the types and causes of soil erosion and land degradation ➤ Explain the principles of soil conservation and provide solutions to soil erosion and soil degradation ➤ Compare and contrast approaches to irrigation, fertilization, and pest management in industrial and

sustainable agriculture ➤ Describe the science of genetically modified food and evaluate the debate over its use ➤ Assess the benefits and drawbacks of feedlots and aquaculture ➤ Describe organic agriculture and summarize its recent growth

Iowa farmers Nate Ronsiek (left) and Paul “Butch” Schroeder (right)

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CE N T R A L C A S E S T U DY

Iowa’s Farmers Practice No-Till Agriculture “The nation that destroys its soil destroys itself.”

—U.S. President Franklin D. Roosevelt

“There are two spiritual dangers in not owning a farm. One is the danger of supposing that breakfast comes from the grocery, and the other that heat comes from the furnace.”

—Aldo Leopold, Conservationist and philosopher

I owa farmers Paul “Butch” Schroeder and his brother David know that their livelihoods de-

pend on keeping their soil healthy and productive. The Schroeder brothers farm 1,200 ha

(3,000 acres) in western Iowa, where rich prairie soils have historically made for bountiful

grain harvests.

Yet the Schroeders also know that repeated cycles of plowing and planting since farmers first settled the region have diminished the soil’s productivity. They know that much of the top- soil—the valuable surface layer richest in organic mat- ter and nutrients—has been lost to erosion: washed away by water and blown away by wind. Turning the earth by tilling (plowing, disking, har- rowing, or chiseling) aerates the soil and works weeds and old crop residue into the soil to nourish it, but tilling also leaves the surface bare, allowing wind and water to erode away precious topsoil.

As a result, the Schroeder brothers abandoned the conventional practice of tilling the soil after har- vests and instead turned to no-till farming. Rather than plowing after each harvest, they began leav- ing crop residues atop their fields, keeping the soil covered with plant material at all times. To plant the next crop, they cut a thin, shallow groove into the soil surface, dropped in seeds, and covered them. By planting seeds of the new crop through the residue of the old, less soil erodes away, organic material ac- cumulates, and the soil soaks up more water—all of which encourages better plant growth. On portions of their land where some tilling is required, they prac- tice conservation tillage, an approach involving limited

tilling—only as much as is needed.

The Schroeders have found that no-till farming saves time and money as well. By forgoing tilling, they reduce the number of passes they need to make on the tractor, which saves fuel, time, effort, and wear and tear on equipment.

Butch and David Schroed- er also practice other con- servation measures on their

land. They take soil samples to determine how much fertilizer different areas need, so as not to overapply it. They employ planting methods designed to reduce erosion. They forgo farming on lands that are vulner- able or have poor soil, retiring them as part of the U.S. government’s Conservation Reserve Program, which pays farmers to take highly erodible land out of culti- vation. All these measures save farmers money while protecting environmental quality and nurturing soil as an investment for sustainable yields in the future.

Future investments are important when a family farm is passed down to the next generation. In Sioux County in northwest Iowa, 26-year-old Nate Ronsiek has taken charge of the farm his late father Vince left to him. Nate and his wife Rachel are putting into prac- tice the strategies for conservation that Nate’s father taught him, as well as those he learned as a student at Kansas State University.

Pacific Ocean

Atlantic Ocean

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SOUTH AMERICA

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every 5 seconds, somewhere in the world, a child starves to death. Many people are undernourished because they are too poor to purchase the food they need, but political obstacles, conf lict, and inefficiencies in distribution contribute signifi- cantly to hunger as well.

Globally, the number of people suffering from under- nourishment fell steadily from 1970 through the late 1990s (FIGURE 7.2). The percentage of undernourished people in developing countries, where hunger issues are most pro- nounced, fell even more steeply. These encouraging trends were reversed because of rising food prices in the 2000s and the economic slump of 2008–2009, and both the number and percentage of hungry people increased. But in 2010 the

“Nate has been farming a short time, but he’s doing a lot of things right on his farm that are sav- ing him money and improving the environment,” says Greg Marek, a conservationist with the local Natural Resource Conservation Service office.

To raise grain for their 65 stock cows, Ronsiek practices no-till farming. He wanted to test the ap- proach for himself, so he worked with agricultural ex- tension agents from Iowa State University to conduct experiments on his own land and compare results from no-till fields and conventional fields. After three years, his no-till fields produced as much corn as the con- ventional fields while requiring less time and money. Ronsiek says he can clearly see how water infiltrates better in the no-till fields and how those fields suffer less erosion.

“I’m excited,” Ronsiek says. “In future growing seasons yields are expected to increase—profit po- tential, too. What I don’t spend on fuel and time for conventional tillage field trips I can invest elsewhere on the farm.”

By enhancing soil conditions and reducing erosion, no-till techniques are benefiting Iowa’s people and en- vironment as well, cutting down on pollution in its air, waterways, and ecosystems. Similar effects are being felt elsewhere in the world where no-till methods are being applied.

No-till farming is not a panacea everywhere. But in suitable regions, proponents say it can help make agriculture sustainable. We will need sustainable agri- culture if we are to feed the world’s human population while protecting the natural environment, including the soils that vitally support our production of food. ■

THE RACE TO FEED THE WORLD Thanks to the efforts of farmers such as the Schroeder broth- ers and Nate Ronsiek, our ability to produce food has grown even faster than global population over the past half-century (FIGURE 7.1). Improving people’s quality of life by producing more food per person is a monumental achievement of which humanity can be proud.

However, not all of the 7 billion people alive today have enough to eat, and we expect to add an additional 2 billion people to the human population by 2050. Providing food security, the guarantee of an adequate, safe, nutritious, and reliable food supply available to all people at all times, will therefore be one of our greatest challenges in coming decades.

We face undernutrition, overnutrition, and malnutrition Despite our rising food production, 925 million people world- wide suffer from undernutrition, receiving fewer calories than the minimum dietary energy requirement. As a result,

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FIGURE 7.1  Global production of most foods has risen more quickly than world population over the past half-century. This means that we have produced more food per person each year. Trend lines show cumulative increases relative to 1961 levels (for example, a value of 2.0 means twice the 1961 amount). Population is measured in number of people, and food is measured by weight. Data from U.N. Food and Agriculture Organization (FAO).

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Percentage of undernourished people

Number of undernourished people

FIGURE 7.2  The number of people suffering undernourishment in the world declined from 1970 through the late 1990s, while the percentage of people in developing nations who were undernour- ished fell still more. However, both of these indicators of hunger increased recently in response to economic conditions. Data from Food and Agriculture Organization of the United Nations, Rome, 2010. The state of food insecurity in the world, 2010. Rome.

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Children who have recently stopped receiving protein from breast-feeding are most at risk for developing kwashiorkor, which causes bloating of the abdomen, deterioration and dis- coloration of hair, mental disability, immune suppression, de- velopmental delays, and reduced growth. Protein deficiency together with a lack of calories can lead to marasmus, which causes wasting or shriveling among millions of children in the developing world. Dietary conditions such as anemia (a lack of dietary iron which causes fatigue and developmental disabilities), iodine deficiency (which causes swelling of the thyroid gland and brain damage), and vitamin A deficiency (which leads to blindness) are also alarmingly prevalent.

Some biofuels reduce food supplies In recent years, some well-intentioned efforts to promote renewable energy have had unintended consequences that have affected people’s access to nutritious foods. Biofuels (pp. 358-361) are fuels derived from organic materials and used in internal combustion engines as replacements for petroleum. In the United States, ethanol produced from corn (pp. 359-361) is the primary biofuel.

When government subsidies for ethanol were expanded in 2007, U.S. ethanol production nearly doubled as new etha- nol facilities opened and farmers began selling their corn for ethanol instead of for food. In Iowa, for example, over half of the corn grown in the state is used for ethanol production.

The use of corn for fuel production caused a scarcity of corn worldwide, and prices for basic foods skyrocketed. The situation worsened when prices for other staple grains also rose because farmers shifted fields formerly devoted to food crops into biofuel production (Chapter 16). For low-income people, the steep rise in food prices was frightening. Thou- sands staged protests, and riots erupted in many nations. This food crisis contributed to the increase in global hunger shown in Figure 7.2.

THE CHANGING FACE OF AGRICULTURE If we are to increase food security for all people, we will need to examine the ways we produce our food and how we can make them more sustainable. As the human population has grown, so have the amounts of land and resources we devote to agriculture. We can define agriculture as the practice of raising crops and livestock for human use and consumption.

We obtain most of our food and fiber from cropland, land used to raise plants for human use, and from rangeland, land used for grazing livestock. Agriculture currently covers 38% of Earth's land surface. Of this land, 26% is rangeland and 12% is cropland.

Industrial agriculture is a recent human invention During most of the human species’ 160,000-year existence, we were hunter-gatherers, depending on wild plants and animals for our food and fiber. Then about 10,000 years ago, as glaciers retreated and the climate warmed, people in some cultures began to raise plants from seed and to domesticate animals.

number of undernourished people declined from the previ- ous year, in large part because of more favorable economic conditions in developing countries. Moreover, hunger levels, as a percentage of population, are substantially lower than the rates that existed 40 years ago.

Although 1 billion people lack access to nutritious foods, many others consume too many calories each day and suffer from overnutrition. Overnutrition leads to unhealthy weight gain, which leads to cardiovascular disease, diabetes, and other health problems. In the United States, more than three in five adults are technically overweight, and more than one in four are obese. But overnutrition is a global problem. The World Health Organization estimates that in 2008, 1.5 billion adults worldwide were overweight and that at least 500 million were obese. It predicts that by 2015 those numbers will rise to 2.3 billion and 700 million.

Just as the quantity of food a person eats is important for health, so is the quality of food. Malnutrition, a shortage of nutrients the body needs, occurs when a person fails to obtain a complete complement of vitamins and minerals. Malnutri- tion can easily lead to disease (FIGURE 7.3). For example, peo- ple who eat a diet that is high in starch but deficient in pro- tein or essential amino acids (p. 28) can develop kwashiorkor.

FIGURE 7.3  Millions of children, including this child with his mother in Somalia, suffer from forms of malnutrition, such as kwashiorkor and marasmus.

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the Green Revolution. This agricultural “revolution” intro- duced new technology, crop varieties, and farming practices to the developing world and drastically increased food pro- duction in these nations.

The transfer of the technology to the developing world that marked the Green Revolution began in the 1940s, when the late U.S. agricultural scientist Norman Borlaug intro- duced Mexico’s farmers to a specially bred type of wheat (FIGURE 7.4). This strain of wheat produced large seed heads, was resistant to diseases, was short in stature to resist wind, and produced high yields. Within two decades of planting this new crop, Mexico tripled its wheat production and began ex- porting wheat. The stunning success of this program inspired similar projects around the world. Borlaug—who won the Nobel Peace Prize for his work—took his wheat to India and Pakistan and helped transform agriculture there.

Soon many developing countries were doubling, tripling, or quadrupling their yields using selectively bred strains of wheat, rice, corn, and other crops from industrialized nations. These crops dramatically increased yields and helped millions avoid starvation. When Borlaug died in 2009 at age 95, he was widely celebrated as having “saved more lives than anyone in history.”

The effects of industrial agriculture have been mixed Industrial agriculture has allowed food production to keep pace with our growing population, but it has many adverse environmental and social impacts. On the positive side, high- input industrial agriculture succeeded dramatically in produc- ing higher crop yields from each hectare of land and reducing pressure to develop natural areas for new farmland. Between 1961 and 2008, for example, food production rose 150% and population rose 100%, while area converted for agriculture in- creased only 10%.

On the negative side, the intensive application of water, fossil fuels, inorganic fertilizers, and synthetic pesticides worsened pollution, topsoil losses, and soil quality. Industri-

For thousands of years, the work of cultivating, harvesting, storing, and distributing crops was performed by human and animal muscle power, along with hand tools and simple ma- chines—an approach known as traditional agriculture. Tra- ditional farmers typically plant polycultures (“many types”) that mix different crops in small plots of farmland, such as the Native American farming systems that mixed maize, beans, squash, and peppers. Traditional agriculture is still practiced to- day but has rapidly been overtaken by newer methods of farm- ing that increase crop yields.

After thousands of years of practicing traditional agri- culture, the industrial revolution (p. 3) introduced large-scale mechanization and fossil fuel combustion to agriculture just as it did to industry. Farmers replaced horses and oxen with machin- ery that provided faster and more powerful means of cultivating, harvesting, transporting, and processing crops. Such industrial agriculture also boosted yields by intensifying irrigation and in- troducing synthetic fertilizers, while the advent of chemical pes- ticides reduced herbivory by crop pests and competition from weeds. Today, industrial agriculture is practiced on over 25% of the world’s cropland and dominates areas such as Iowa.

However, the use of machinery created a need for highly organized approaches to farming, leading to vast areas be- ing planted with single crops in orderly, straight rows. Such monocultures (“one type”) make farming more efficient, but they provide fewer habitats in farm fields, which reduces bio- diversity. Moreover, when all plants in a field are genetically similar, as in monocultures, all are equally susceptible to viral diseases, fungal pathogens, or insect pests that can spread quickly from plant to plant.

Industrial agriculture’s widespread use of genetically simi- lar crop varieties has led to efforts to conserve the wild rela- tives of crop plants and crop varieties indigenous to various regions, because they may contain genes we will one day need to introduce into our commercial crops. Seeds of these spe- cies are stored in some 1,400 seed banks, institutions that preserve seed types, around the world, including a “doomsday seed vault” established in 2008 on the island of Spitsbergen in Arctic Norway. Many agricultural scientists feel that we also need to protect the genetic integrity of wild relatives of crop plants by preventing genetically modified versions of these plants from exchanging genes with them. These scientists want to avoid such genetic "contamination" of wild populations so that we preserve the natural gene combinations of plants that are well adapted to their environments.

Our use of monocultures also contributes to a narrowing of the human diet. Globally, 90% of the food we consume now comes from just 15 crop species and eight livestock species—a drastic reduction in diversity from earlier times. Only 30% of the maize varieties that grew in Mexico in the 1930s exist to- day. In the United States, many fruit and vegetable crops have decreased in diversity by 90% in less than a century.

The Green Revolution boosted production—and exported industrial agriculture The desire for greater quantity and quality of food for our growing population led in the mid- and late-20th century to

FIGURE 7.4  Norman Borlaug holds examples of the wheat variety he bred that helped launch the Green Revolution. The high-yielding, disease- resistant wheat helped boost agricultural productivity in many developing countries.

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riculture and decreasing the pollution these inputs cause. Fossil fuels power farm machinery and the pumps that draw irrigation water. They are also used as raw materials in the syn- thesis of some fertilizers and synthetic pesticides. Low- input agriculture describes agriculture that uses lesser amounts of pesticides, fertilizers, growth hormones, antibiotics, water, and fossil fuel energy than are used in industrial agriculture. Such approaches also seek to reduce food production costs by allowing nature to provide valuable ecosystem services, such as fertilization and pest control, that farmers using industrial agricultural methods must pay for themselves.

In the sections that follow, we will examine how mod- ern food production affects the basic elements of agricul- ture—maintaining soil fertility, watering and fertilizing crops, and controlling agricultural pests—and how more sustainable methods can reduce these impacts while maintaining high crop yields. We will begin with soils, the foundation of agriculture.

SOILS Soil is not merely lifeless dirt; it is a complex system consisting of disintegrated rock, organic matter, water, gases, nutrients, and microorganisms. Healthy soil is vital for agriculture, for forests (Chapter 9), and for the functioning of Earth’s natural systems. Productive soil is a renewable resource. Once deplet- ed, soil may renew itself over time, but this renewal generally occurs very slowly. If we abuse soil through careless or unin- formed practices, we can greatly reduce its ability to support life for long time periods.

We generally overlook the startling complexity of soil. By volume, soil consists very roughly of 50% mineral matter and up to 5% organic matter. The rest consists of pore space taken up by air or water. The organic matter in soil includes living and dead microorganisms as well as decaying material derived from plants and animals. The soil ecosystem supports a diverse collection of bacteria, fungi, protists, worms, insects, and burrowing animals (FIGURE 7.5). The composition of a region’s soil can have as much influence on its ecosystems as do climate, latitude, and elevation.

Soil forms slowly Soil formation begins when the lithosphere’s parent material is exposed to the effects of the atmosphere, hydrosphere, and biosphere (pp. 22–23). Parent material is the base geologic ma- terial in a particular location. It can be hardened lava or vol- canic ash; rock or sediment deposited by glaciers; wind-blown dunes; sediments deposited in riverbeds, f loodplains, lakes, and the ocean; or bedrock, the continuous mass of solid rock that makes up Earth’s crust. Parent material is broken down by weathering, the physical, chemical, and biological pro- cesses that convert large rock particles into smaller particles.

Once weathering has produced fine particles, biological activity contributes to soil formation through the deposi- tion, decomposition, and accumulation of organic matter. As plants, animals, and microbes die or deposit waste, this mate- rial is incorporated amid the weathered rock particles, mixing with minerals. The deciduous trees of temperate forests, for example, drop their leaves each fall, making leaf litter avail- able to the detritivores and decomposers (p. 68) that break it

ial agriculture also requires far more energy than traditional agriculture. From 1900 to 2000, as industrial agriculture ex- panded around the world, humans increased energy inputs into agriculture by 80 times while expanding the world’s cul- tivated area by just 33%. Industrial agriculture also displaces low- income farmers who cannot afford the advanced technol- ogies it requires. This can force poor rural people to migrate to urban areas, as is occurring today in many regions of the developing world (pp. 400-401).

Sustainable agriculture reduces environmental impacts We have achieved our impressive growth in food production by devoting more fossil fuel energy to agriculture; intensify- ing our use of irrigation, fertilizers, and pesticides; planting and harvesting more frequently; cultivating more land; and developing (through crossbreeding and genetic engineering) more productive crop and livestock varieties. However, many of these practices have degraded soils, polluted waters, and affected biodiversity.

We cannot simply keep expanding agriculture into new areas, because land suitable and available for farming is run- ning out. Instead, we must find ways to improve the efficiency of food production in areas already under cultivation. Indus- trial agriculture in some form seems necessary to feed our planet’s 7 billion people, but many experts feel we will be bet- ter off in the long run by raising animals and crops in ways that are less polluting, are less resource-intensive, and cause less impact on natural systems. To this end, many farmers and agricultural scientists are creating agricultural systems that better mimic the way a natural ecosystem functions.

Sustainable agriculture describes agriculture that main- tains the healthy soil, clean water, and genetic diversity essential to long-term crop and livestock production. It is agriculture that can be practiced in the same way far into the future. Treating agricultural systems as ecosystems is a key aspect of sustainable agriculture, and this general lesson applies regardless of location, scale, or the crop involved.

One key component of making agriculture sustainable is reducing the fossil-fuel-intensive inputs we devote to ag-

The Green Revolution and Population In the 1960s, India’s population was skyrocketing, and its traditional agriculture was not producing enough food to support the growth. By adopting

Green Revolution agriculture, India sidestepped mass star- vation. However, Norman Borlaug called his Green Revolu- tion methods “a temporary success in man’s war against hunger and deprivation,” something to give us breathing room in which to deal with what he called the “Population Monster.” Indeed, in the years since intensifying its agricul- ture, India has added several hundred million more people and continues to suffer widespread poverty and hunger.

Do you think the Green Revolution has solved prob- lems, deferred problems, or created new ones? Have the benefits of the Green Revolution outweighed its costs?

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subsoil, and parent material. However, soil scientists often rec- ognize at least three additional horizons, including an O hori- zon (litter layer) that consists primarily of organic matter from organisms (FIGURE 7.6). Soils from different locations vary, and few soil profiles contain all six of these horizons, but any given soil contains at least some of them.

Generally, the degree of weathering and the concentra- tion of organic matter decrease as one moves downward in a soil profile. Minerals are generally transported downward as a result of leaching, the process whereby solid particles sus- pended or dissolved in liquid are transported to another loca- tion. In some soils, minerals may be leached so rapidly that plants are deprived of nutrients.

A crucial horizon for agriculture and ecosystems is the A horizon, or topsoil. Topsoil consists mostly of inorganic min- eral components such as weathered substrate, with organic matter and humus from above mixed in. Topsoil is the portion of the soil that is most nutritive for plants, and it takes its loose texture, dark coloration, and strong water-holding capacity from its humus content. The O and A horizons are home to most of the countless organisms that give life to soil. Topsoil is vital for agriculture, but agriculture practiced unsustainably

down and incorporate its nutrients into the soil. In decom- position, complex organic molecules are broken down into simpler ones, including those that plants can take up through their roots. Partial decomposition of organic matter creates humus, a dark, spongy, crumbly mass of material made up of complex organic compounds. Soils with high humus content hold moisture well and are productive for plant life.

A soil profile consists of layers known as horizons As wind, water, and organisms move and sort the fine parti- cles that weathering creates, distinct layers eventually develop. Each layer of soil is termed a horizon, and the cross-section as a whole, from surface to bedrock, is known as a soil profile.

The simplest way to categorize soil horizons is to recog- nize A, B, and C horizons corresponding respectively to topsoil,

Snail

Soil fungi

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Cicada nymph

Earthworm

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Beetle grub

FIGURE 7.5  Soil is a complex mixture of organic and inorganic components and is full of living organisms whose actions help to keep it fertile. In fact, entire ecosystems exist in soil. Most soil organisms, from bacteria to fungi to insects to earthworms, decompose organic matter. Many, such as earthworms, also help to aerate the soil.

O Horizon

A Horizon

E Horizon

B Horizon

C Horizon

R Horizon

Organic (litter layer)

Topsoil

Eluviated (leaching layer)

Subsoil

Weathered parent material

Rock (parent material)

FIGURE 7.6  Mature soil consists of layers, or horizons, that have different compositions and characteristics. Uppermost is the O horizon, or litter layer (O = organic), consisting mostly of or- ganic matter deposited by organisms. Below it lies the A horizon, or topsoil, consisting of some organic material mixed with mineral components. Minerals and organic matter tend to leach out of the E horizon (E = eluviation, or leaching) into the B horizon, or subsoil, where they accumulate. The C horizon consists largely of weathered parent material and overlies an R horizon (R = rock) of pure parent material.

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(a) Tropical swidden agriculture on nutrient-poor soil

(b) Industrial agriculture on Iowa’s rich topsoil

FIGURE 7.7  In tropical forested areas such as Surinam (a), the traditional form of farming is swid- den agriculture. In this practice, forest is cut, the plot is farmed for one to a few years, and the farmer then moves on to clear another plot. Frequent movement is nec- essary because tropical rainforest soils (see inset) are nutrient-poor and easily depleted. On the Iowa prairie (b), less rainfall means that nutrients are not leached from the topsoil. Organic matter accumu- lates, forming rich soil that can be sustainably farmed. Note the thick, dark layer of topsoil in the inset for the Iowa farm.

over time will deplete organic matter, reducing the soil’s fertil- ity and ability to hold water. When a farmer practices no-till farming, he or she essentially creates an O horizon of crop residue to cover the topsoil and then plants seeds of the new crop through this O horizon into the protected topsoil layer.

Regional differences in soil traits affect agriculture Soil characteristics vary from place to place, and are deeply af- fected by variables like climate. In the Amazon, the enormous amount of rain that falls leaches minerals and nutrients out of the topsoil and E horizon. Anything not captured by plants is taken quickly down to the water table, below the reach of plants’ roots. Warm temperatures speed the decomposition of leaf litter and the uptake of nutrients by plants, so only small amounts of humus remain in the thin topsoil layer. As a result,

when tropical forest is cleared for farming, cultivation quickly depletes the soil’s fertility.

The traditional form of agriculture in tropical forested ar- eas is swidden agriculture, in which the farmer cultivates a plot for one to a few years and then moves on to clear another plot, leaving the first to grow back to forest (FIGURE 7.7A). At low population densities this can be sustainable, but with today’s dense human populations, soils may not be allowed enough time to regenerate. As a result, intensive agriculture has de- graded the soils of many tropical areas.

On the Iowa prairie, however, there is less rainfall, and therefore less leaching, which keeps nutrients within reach of plants’ roots. Plants return nutrients to the topsoil when they die, maintaining its fertility. The thick, rich topsoil of temper- ate grasslands can be farmed repeatedly with minimal loss of fertility if techniques such as no-till farming and conservation tillage are used (FIGURE 7.7B).

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▶ Overgrazing rangeland with more livestock than the land can support

▶ Clearing forests on steep slopes or with large clear-cuts (pp. 194-195 )

Soil erosion is a global problem In today’s world, humans are the primary cause of erosion, and we have accelerated it to unnaturally high rates. In a 2004 study, geologist Bruce Wilkinson concluded that hu- man activities move over 10 times more soil than all other natural processes on the surface of the planet combined. A 2007 study by soil scientist David Montgomery found an even greater degree of human impact. Montgomery’s study also pointed toward a solution, revealing that land farmed under conservation approaches erodes at slower rates than land un- der conventional farming.

More than 19 billion ha (47 billion acres) of the world’s croplands suffer from erosion and other forms of soil degra- dation resulting from human activities. In the past decade, China lost an area of arable farmland the size of Indiana. Farmlands in the United States lose roughly 5 tons of soil for every ton of grain harvested. In Africa, soil degradation over the next 40 years could reduce crop yields by half. Couple these declines in soil quality and crop yields with the rapid population growth occurring in many of these areas, and we begin to see why some observers describe the future of agri- culture as a crisis situation.

Desertification reduces productivity of arid lands Much of the world’s population lives and farms in dry- lands , arid and semi-arid environments that cover about 40% of Earth’s land surface. Precipitation in these regions is too meager to meet the demand for water from growing human populations, so drylands are prone to desertifica- tion. Desertification describes a form of land degradation in which more than 10% of productivity is lost as a result of erosion, soil compaction, forest removal, overgrazing, drought, salinization, climate change, water depletion, and

MAINTAINING HEALTHY SOILS Throughout the world, especially in drier regions, it has gotten more difficult to raise crops and graze livestock. Soils have deteriorated in quality and declined in productivity—a process termed soil degradation . Each year, our planet gains 80 million people yet loses 5–7 million ha (12–17 million acres, about the size of West Virginia) of productive cropland to degradation. The common causes include soil erosion, nu- trient depletion, water scarcity, salinization (p. 145 ), waterlog- ging (p. 145 ), chemical pollution, changes in soil structure and pH, and loss of organic matter from the soil. Over the past 50 years, scientists estimate that soil degradation has reduced potential rates of global grain production on cropland by 13%.

Erosion can degrade ecosystems and agriculture Erosion is the removal of material from one place and its transport toward another by the action of wind or water ( FIGURE 7.8 ). Deposition occurs when eroded material arrives at a new location and is deposited. Erosion and deposition are natural processes that in the long run can help create soil. Flowing water can deposit freshly eroded sediment rich in nu- trients across river valleys and deltas, producing fertile and productive soils. However, erosion often is a problem locally for ecosystems and agriculture because it generally occurs much more quickly than soil is formed. Erosion also tends to remove topsoil, the most valuable soil layer for living things. In general, steeper slopes, greater precipitation intensities, and sparser vegetative cover all lead to greater water erosion.

People have made land more vulnerable to erosion through three widespread practices:

▶ Overcultivating fields through poor planning or excessive tilling

FIGURE 7.8  Water erosion, like that occurring here on farmland in Iowa, can readily remove soil from areas where soil is exposed.

Q: What is “slash-and-burn” agriculture?

A: Soils in tropical forests are not well suited for cultivating crops because they contain relatively low levels of plant nutrients. But although the soil is nutrient-poor, there are large amounts of nutrients tied up in the forest’s lush vegetation. When farmers develop plots of tropical rainforest for agriculture, they enrich the soil by cutting down and burning the plants on the site. The nutrient-rich ash is then tilled into the soil, providing sufficient fertility to grow crops. The practice is therefore called slash-and-burn agriculture.

The nutrients from the ash, however, are usually depleted in only one to a few years. Lacking the resources to purchase synthetic fertilizer, poor farmers simply move deeper into the forest, repeat the process on a new plot of forested land, and cause further impacts on these productive and biologically diverse ecosystems.

FAQ

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Sustainable agriculture begins with soil management A number of farming techniques can reduce the impacts of conventional cultivation on soils and combat soil degrada- tion (FIGURE 7.10).

Crop rotation In crop rotation, farmers alternate the type of crop grown in a given field from one season or year to the next (FIGURE 7.10A). Rotating crops can return nutrients to the soil, break cycles of disease associated with continu- ous cropping, and minimize the erosion that can come from letting fields lie fallow. Many U.S. farmers rotate their fields between wheat or corn and soybeans from one year to the next. Soybeans are legumes, plants that have specialized bac- teria on their roots that fix nitrogen (pp. 38–39), revitalizing soil that the previous crop had partially depleted of nutrients. Crop rotation also reduces insect pests; if an insect is adapted to feed and lay eggs on one crop, planting a different type of crop will leave its offspring with nothing to eat.

In a practice similar to crop rotation, many no-till farm- ers such as those in Iowa plant cover crops, such as nitrogen-

other factors. Most such degradation results from wind and water erosion.

By some estimates, desertification endangers the food supply or well-being of more than 1 billion people in over 100 countries, and costs tens of billions of dollars in income each year through reduced productivity. A 2007 United Nations report estimated that desertification could worsen as climate change alters rainfall patterns, displacing as many as 50 mil- lion people in 10 years. China alone loses $6.5 billion annually from desertification. In its western reaches, desert areas are expanding and joining one another because of overgrazing from over 400 million goats, sheep, and cattle.

As a result of desertification, in recent years gigantic dust storms from denuded land in China have blown across the Pacific Ocean to North America, and dust storms from Af- rica’s Sahara Desert have blown across the Atlantic Ocean to the Caribbean Sea (see Figure 13.6, p. 283). Such massive dust storms occurred in the United States during the Dust Bowl days of the early 20th century, when desertification shook American agriculture and society to their roots.

The Dust Bowl prompted the United States to fight erosion Prior to large-scale cultivation of North America’s Great Plains, native prairie grasses of this temperate grassland region held soils in place. In the late 19th and early 20th centuries, many homesteading settlers arrived in Oklaho- ma, Texas, Kansas, New Mexico, and Colorado with hopes of making a living there as farmers. Farmers grew abun- dant wheat, and ranchers grazed many thousands of cattle, sometimes expanding onto unsuitable land and contribut- ing to erosion by removing native grasses and altering soil structure.

In the early 1930s, a drought exacerbated the ongoing human impacts, and the region’s strong winds began to erode millions of tons of topsoil. Dust storms traveled up to 2,000 km (1,250 mi), blackening rain and snow as far away as New York and Washington, D.C. Some areas lost 10 cm (4 in.) of topsoil in a few years. The most-affected region in the southern Great Plains became known as the Dust Bowl, a term now also used for the historical event itself (FIGURE 7.9). The “black blizzards” of the Dust Bowl forced thou- sands of farmers off their land.

In response, the U.S. government, along with state and local governments, increased support for research into soil conservation measures. The U.S. Congress passed the Soil Conservation Act of 1935, establishing the Soil Conservation Service (SCS). This new agency worked closely with farmers to develop conservation plans for individual farms.

The SCS (currently named the Natural Resources Con- servation Service) served as a model for other nations that established their own soil conservation agencies. In South America, no-till agriculture has exploded in popularity and now covers a large proportion of farmland in Argentina, Bra- zil, and Paraguay. The shift to no-till farming across this vast region came about largely through local grassroots organiza- tion by farmers, with the help of agronomists and govern- ment extension agents who provided them with information and resources.

(a) Kansas dust storm, 1930s

(b) Dust Bowl region

(a) Kansas dust storm, 1930s

(b) Dust Bowl region

FIGURE 7.9  Drought combined with poor agricultural practices brought devastation and despair to millions of U.S. farmers in the 1930s in the Dust Bowl region of the southern Great Plains. The pho- to (a) shows towering clouds of dust approaching houses near Dodge City, Kansas, in a 1930s dust storm. The map (b) shows the Dust Bowl region, with darker colors indicating the areas most affected.

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replenishing clover, to prevent erosion during times of year when the main crops are not growing.

Contour farming Water running down a hillside with little vegetative cover can easily carry soil away, so farmers have developed several methods for cultivating slopes. Con- tour farming (FIGURE 7.10B) consists of plowing furrows

(a) Crop rotation

(e) Shelterbelts (f) No-till farming

(b) Contour farming

(d) Intercropping

FIGURE 7.10  The world’s farmers have adopted various strategies to conserve soil. Rotating crops such as soybeans and corn (a) helps restore soil nutrients and reduce impacts of crop pests. Contour farming (b) reduces erosion on hillsides. Terracing (c) minimizes erosion in steep mountainous areas. Intercropping (d) can reduce soil loss while maintaining soil fertility. Shelterbelts (e) protect against wind erosion. In (f), corn grows up from amid the remnants of a “cover crop” used in no-till agriculture.

sideways across a hillside, perpendicular to its slope and fol- lowing the natural contours of the land. In contour farming, the side of each furrow acts as a small dam that slows runoff and captures eroding soil. Contour farming is most effective on gradually sloping land with crops that grow well in rows. Iowa farmers Butch and David Schroeder practice contour farming on all their fields. They also plant buffer strips of

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the furrow and closes the furrow over the seeds, minimizing disturbance to the soil.

By increasing organic matter and soil biota while re- ducing erosion, no-till farming and conservation tillage can improve soil quality and combat global climate change by storing carbon in soils. In the United States today, nearly one-quarter of farmland is under no-till cultivation, and over 40% is farmed using conservation tillage (FIGURE 7.11). According to U.S. government figures, erosion rates in the United States declined from 9.1 tons/ha (3.7 tons/acre) in 1982 to 5.9 tons/ha (2.4 tons/acre) in 2003, thanks to con- servation tillage.

No-till and conservation tillage methods have become most widespread in subtropical and temperate South America. In Brazil, Argentina, and Paraguay, over half of all cropland is now under no-till cultivation. In this part of the world, heavy rainfall promotes erosion, causing tilled soils to lose organic matter and nutrients, and hot weather can overheat tilled soil. Thus, the no-till approach is especially helpful here, and re- sults have exceeded those in the United States: Crop yields increased (in some cases they nearly doubled), erosion was reduced, soil quality was enhanced, and pollution declined, all while costs to farmers dropped by roughly 50%.

Critics of no-till farming in the United States have noted that this approach often requires substantial use of chemical herbicides (because weeds are not physically re- moved from fields) and synthetic fertilizer (because other plants take up a significant portion of the soil’s nutrients). In many industrialized countries, this has indeed been the case. Proponents, however, point out that in develop- ing regions of South America, farmers have departed from the industrialized model by relying more heavily on green manures (dead plants as fertilizer) and by rotating fields with cover crops, including nitrogen-fixing legumes. The manures and legumes nourish the soil, and cover crops re- duce weeds by taking up space the weeds might occupy. Al- though this approach is often not practical for large-scale intensive agriculture, farmers are educating themselves on the available approaches and choosing those that are best for their farms.

vegetation along the borders of their fields and along nearby streams, which further protects against erosion and water pollution.

Terracing On extremely steep terrain, terracing (FIGURE 7.10C) is the most effective method for preventing erosion. Terraces are level platforms, sometimes with raised edges, that are cut into steep hillsides to contain water from irri- gation and precipitation. Terracing transforms slopes into series of steps like a staircase, enabling farmers to culti- vate hilly land without losing huge amounts of soil to water erosion.

Intercropping Farmers may also minimize erosion by i ntercropping, planting different types of crops in alternating bands or other spatially mixed arrangements (FIGURE 7.10D). Intercropping helps slow erosion by providing more ground cover than does a single crop. Like crop rotation, intercrop- ping reduces vulnerability to insects and disease and, when a nitrogen-fixing legume is used, replenishes the soil. In Brazil, some no-till farmers intercrop cover crops with food crops such as maize, soybeans, wheat, onions, cassava, grapes, to- matoes, tobacco, and orchard fruit.

Shelterbelts A widespread technique to reduce ero- sion from wind is to establish shelterbelts, or windbreaks (FIGURE 7.10E). These are rows of trees or other tall plants that are planted along the edges of fields to slow the wind. On the Great Plains, fast-growing species such as poplars are of- ten used. Shelterbelts can be combined with intercropping by planting mixed crops in rows surrounded by or interspersed with rows of trees that provide fruit, wood, or protection from wind.

Conservation tillage Conservation tillage describes an array of approaches that reduce the amount of tilling relative to conventional farming. No-till farming is the ultimate form of conservation tillage. To plant using the no-till method (FIG- URE 7.10F), a tractor pulls a “no-till drill” that cuts furrows through the O horizon of dead weeds and crop residue and the upper levels of the A horizon. The device drops seeds into

Percent no-till 0–10%

10–25% 25–50% 50–100%

FIGURE 7.11  Across the United States, red and orange colors on this county-by-county map show that no-till methods are practiced most in the Midwest and along the central and southern Atlantic seaboard. Data from Conservation Technology Information Center, National Crop

Residue Management Survey, 2004.

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Agricultural subsidies affect soil degradation In theory, the marketplace should discourage people from farming and grazing using intensive methods that degrade the land they own if such practices are not profitable. But land degradation often unfolds gradually, whereas farmers and ranchers generally cannot afford to go without profits in the short term, even if they know conservation is in their long-term interests.

Many nations spend billions of dollars in government subsidies to support agriculture. Roughly one-fifth of the in- come of the average U.S. farmer comes from subsidies. Propo- nents of such subsidies stress that the uncertainties of weather make profits and losses from farming unpredictable from year to year. To persist, these proponents say, an agricultural sys- tem needs some way to compensate farmers for bad years. This may be the case, but subsidies can encourage people to culti- vate land that would otherwise not be farmed; to produce more food than is needed, driving down prices for other producers; and to practice methods that further degrade the land. Thus, opponents of subsidies argue that subsidizing environmentally destructive agricultural practices is unsustainable. They sug- gest that a better model is for farmers to buy insurance to pro- tect themselves against short-term production failures.

A number of U.S. and international programs promote soil conservation While government subsidies may promote soil degradation, the U.S. Congress has also enacted a number of provisions promoting soil conservation through the farm bills it pass- es every five to six years. Many of these provisions require farmers to adopt soil conservation plans and practices before they can receive government subsidies.

The Conservation Reserve Program, established in the 1985 farm bill, pays farmers to stop cultivating highly erod- ible cropland and instead place it in conservation reserves

Grazing practices can contribute to soil degradation We have focused in this chapter largely on the cultivation of crops as a source of impacts on soils and ecosystems, but raising livestock also has impacts. Humans keep a total of 3.4 billion cattle, sheep, and goats that graze primarily on grasses on the open range. As long as livestock populations do not exceed a range’s carrying capacity (p. 58) and do not consume grass faster than it can regrow, grazing may be sus- tainable. However, when too many livestock eat too much of the plant cover, it impedes plant regrowth and prevents the replacement of biomass, and the result is overgrazing.

When livestock remove too much plant cover, soil is exposed and made vulnerable to erosion. In a positive feed- back cycle (pp. 22–23), soil erosion makes it difficult for vegetation to regrow, a problem that perpetuates the lack of cover and gives rise to more erosion (FIGURE 7.12). Moreover, non-native weedy plants that are unpalatable to livestock may outcompete native vegetation in the new, modified environment.

Too many livestock trampling the ground can also com- pact soils and alter their structure. Soil compaction makes it more difficult for water to infiltrate, for soils to be aerated, for plants’ roots to expand, and for roots to conduct cellular res- piration (pp. 30–31). All of these effects further decrease the growth and survival of native plants.

As a cause of soil degradation worldwide, overgrazing is equal to cropland agriculture, and it is a greater cause of de- sertification. Fully 70% of the world’s rangeland is classified as degraded, and lost productivity on these lands is estimated at $23.3 billion per year. Rangelands in the western United States have often been overgrazed by a “tragedy of the commons” process (pp. 3–4), but today increasing numbers of ranchers are working cooperatively with government agencies, envi- ronmental scientists, and even environmental advocates to find ways to ranch more sustainably and safeguard the health of the land.

Exposes bare topsoil

Wind and water erosion

Decreases water infiltration

Decreases grass growth and survival

Invasive species gain foothold and

outcompete natives in altered environment

Overgrazing

Decreases aeration

Removes native grass

Compacts soil and damages structure

FIGURE 7.12  When grazing by livestock exceeds the carrying capac- ity of rangelands and their soil, it can set in motion a series of conse- quences and positive feedback loops that degrade soils and grassland ecosystems.

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planted with grasses and trees. Lands under the Conservation Reserve Program now cover an area nearly the size of Iowa, and the United States Department of Agriculture (USDA) es- timates that each dollar invested in this program saves nearly 1 ton of topsoil. Besides reducing erosion, the Conservation Reserve Program generates income for farmers, improves water quality, and provides habitat for wildlife. Nationwide, the government pays farmers about $1.8 billion per year for the conservation of lands totaling between 12–16 million ha (30–40 million acres).

Congress reauthorized and expanded the Conservation Reserve Program in the farm bills of 1996, 2002, and 2008. Butch and David Schroeder are among the many farmers in Iowa and across the nation who have utilized this program, taking land with damaged and erodible soil out of produc- tion. The 2008 bill limited total conservation reserve lands to 32 million acres but also funded 14 other programs for the conservation of grasslands, wetlands, wildlife habitat, and other resources. Internationally, the United Nations pro- motes soil conservation and sustainable agriculture through a variety of programs led by the Food and Agriculture Or- ganization (FAO).

WATERING AND FERTILIZING CROPS Soil degradation is not the only impact of agriculture on the environment. We affect natural systems, sometimes far away from farm fields, when we supply plants with supplemental water and nutrients to boost crop yields using unsustainable approaches.

Irrigation boosts productivity but can damage soil Plants require water for optimum growth, and people have long supplemented the water that crops receive from rain- fall. The artificial provision of water to support agriculture is known as irrigation. By irrigating crops, people maintain high yields in times of drought and turn previously dry and unproductive regions into fertile farmland.

Worldwide, irrigated acreage has increased along with the adoption of industrial farming methods, and 70% of the fresh water withdrawn by humans is applied to crops. In some cases, withdrawing water for irrigation has depleted aquifers and dried up rivers and lakes (pp. 262-263).

In some locations, excessive irrigation has degraded soils. Waterlogging occurs when over-irrigation causes the water table to rise to the point that water drowns plant roots, depriv- ing them of access to gases and essentially suffocating them. A more frequent problem is salinization, the buildup of salts in surface soil layers. In dryland areas where precipitation is minimal and evaporation rates are high, the evaporation of water from the soil’s A horizon may pull water with dissolved salts up from lower horizons. When the water evaporates at the surface, those salts remain on the soil, often turning the soil surface white. Salinization now inhibits production on one-fifth of all irrigated cropland globally, costing more than $11 billion each year.

(a) Conventional irrigation

(b) Drip irrigation

FIGURE 7.13  Currently, plants take up less than half the water we apply in irrigation. Conventional methods (a) lose a great deal of water to evaporation. In more-efficient irrigation approaches, water is precisely targeted to plants. In drip irrigation systems, such as this one watering grape vines in California (b), hoses are arranged so that water drips directly onto the plants.

Sustainable approaches to irrigation maximize efficiency One of the most effective ways to reduce water use in agri- culture is to better match crops and climate. Many arid re- gions have been converted into productive farmland through extensive irrigation, often with the support of government subsidies that make irrigation water artificially inexpensive. Some farmers in these areas cultivate crops that require large amounts of water, such as rice and cotton. This leads to exten- sive water losses from evaporation in the arid climate. Choos- ing other crops that require far less water, such as beans or wheat, could enable these areas to remain agriculturally pro- ductive and yet greatly reduce water use.

Another approach is to embrace new technologies that improve water use efficiency in irrigation. Currently, irriga- tion efficiency worldwide is low, as plants end up using only 43% of the water that we apply—the rest evaporates or soaks into the soil away from plant roots (FIGURE 7.13A). New drip irrigation systems that deliver water directly to plant roots can increase efficiencies to over 90% (FIGURE 7.13B). Such systems

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and other sources spurs phytoplankton blooms in the Gulf of Mexico near the mouth of the Mississippi River and creates an oxygen-depleted “dead zone” that kills animal and plant life (Chapter 2). Such eutrophication (pp. 23–25, 267–268) o ccurs at countless river mouths, lakes, and ponds throughout the world. Air pollution can also arise from components of some nitrogen fertilizers that evaporate into the air, contributing to the formation of photochemical smog (pp. 288–289) and acid deposition (pp. 291–294).

Sustainable fertilizer use involves monitoring and targeting nutrients Sustainable approaches to fertilizing crops target the delivery of nutrients to plant roots and avoid the overapplication of fertilizer. This is accomplished in many ways. Farmers using drip irrigation systems can add fertilizer to irrigation water, thereby releasing it only above plant roots. No-till or conser- vation tillage systems often inject fertilizer along with seeds, concentrating it near the developing plant. Farmers can also avoid overapplication by regularly monitoring soil nutrient content and applying fertilizer only when soil nutrient levels are too low, as was done by the Schroeder brothers in Iowa. Strips of vegetation planted at the edges of fields and along streams can capture nutrient runoff along with eroded soils.

Sustainable agriculture also embraces the use of organic fertilizers, as they can provide some benefits that inorganic fertilizers cannot. Organic fertilizers provide not only nutri- ents, but also organic matter that improves soil structure, nutri- ent retention, and water-retaining capacity. The use of organic fertilizers is not without cost, though. For instance, when ma- nure is applied in amounts needed to supply sufficient nitrogen for a crop, it may introduce excess phosphorus that can run off into waterways. Accordingly, sustainable approaches do not rely solely on organic fertilizers, but rather integrate them with the targeted delivery of nutrients using inorganic fertilizer.

CONTROLLING PESTS Throughout the history of agriculture, the insects, fungi, viruses, rats, and weeds that eat or compete with our crop plants have taken advantage of the ways we cluster food plants into agricultural fields. Pests and weeds pose an especially great threat to monocultures, where a pest adapted to special- ize on the crop can move easily from plant to plant.

What people term a pest is any organism that damages crops that are valuable to us. What we term a weed is any plant that competes with our crops. There is nothing inherently malevolent in the behavior of a pest or a weed. These organ- isms are simply trying to survive and reproduce, but they af- fect farm productivity when doing so.

We have developed thousands of chemical pesticides To suppress pests and weeds, people have developed thou- sands of chemicals to kill insects (insecticides), plants (herbicides), and fungi ( fungicides). Such poisons are collec- tively termed pesticides. The highly modified ecosystems of industrial farming limit the ability of natural mechanisms

were once quite expensive to install and were largely used by farmers in wealthier nations, but are becoming cheap enough that more farmers in developing countries will be able to af- ford them. Drip systems are not utilized in the vast fields of monocultures like those profiled in the Central Case Study, but they are useful on smaller plots of farmland and with perennial plants, such as fruit trees.

Fertilizers boost crop yields but can be overapplied Plants require nitrogen, phosphorus, and potassium to grow, as well as smaller amounts of more than a dozen other nutri- ents. Leaching and uptake by plants removes these nutrients from soil, and if soils come to contain too few nutrients, crop yields decline. Therefore, we go to great lengths to enhance nutrient-limited soils by adding fertilizer, substances that contain essential nutrients.

There are two main types of fertilizers. Inorganic fertilizers are mined or synthetically manufactured mineral supplements. Organic fertilizers consist of the remains or wastes of organ- isms and include animal manure, crop residues, fresh vegetation (green manure), and compost, a mixture produced when de- composers break down organic matter, including food and crop waste, in a controlled environment.

Historically, humans relied on organic fertilizers to replenish soil nutrients. But during the latter half of the 20th century, farmers in industrialized and Green Revolution regions widely embraced the use of inorganic fertilizers (FIGURE 7.14). This use has greatly boosted our global food production, but the overapplication of inorganic fertilizers is causing increasingly severe pollution problems. Inorganic fertilizers are generally more susceptible to leaching than or- ganic fertilizers and more readily contaminate groundwater supplies. Nutrients from these fertilizers can also have im- pacts far beyond the boundaries of the fields. We saw how nitrogen and phosphorus runoff from farms in the Midwest

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FIGURE 7.14  Use of synthetic inorganic fertilizers has risen sharply over the past half-century and now stands at over 147 mil- lion metric tons annually. (The temporary drop during the early 1990s was due to economic decline in countries of the former Soviet Union following that nation’s dissolution.) Data from Food and Agriculture Organization of the United Nations (FAO).

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the genes for pesticide resistance will be passed to their off- spring. As resistant individuals become more prevalent in the pest population, insecticide applications will cease to be effec- tive and the population will increase in number (FIGURE 7.15).

In many cases, industrial chemists are caught up in an e volutionary arms race (p. 67) with the pests they battle, rac- ing to increase or retarget the toxicity of their chemicals while the armies of pests evolve ever-stronger resistance to their efforts. Because we seem to be stuck in this cyclical process, it has been nicknamed the “pesticide treadmill.” As of 2011, among arthropods (insects and their relatives) alone, there were more than 9,900 known cases of resistance by 586 species to over 330 insecticides. Hundreds more weed species and plant diseases have evolved resistance to herbicides and other pesticides. Many species, including insects such as the green peach aphid, Colorado potato beetle, and diamondback moth, have evolved resistance to multiple chemicals.

Biological control pits one organism against another Because of pesticide resistance, toxicity to nontarget organ- isms, and human health risks from some synthetic chemi- cals, agricultural scientists increasingly battle pests and weeds with organisms that eat or infect them. This more

to control pest populations. Hence, as industrial agriculture grew in use, farmers turned to chemical means to control agricultural pests.

Three-quarters of all pesticides are applied on agricultural land. Since 1960, pesticide use has risen fourfold worldwide. Usage in industrialized nations has leveled off in the past two decades, but it continues to rise in the developing world. Exposure to synthetic pesticides can have health consequences for people and other organisms under some circumstances (Chapter 10), so their use in food production can have far- reaching effects.

Pests evolve resistance to pesticides Despite the toxicity of these chemicals, their effectiveness tends to decline with time as pests evolve resistance to them. Recall from our discussion of natural selection (pp. 46–49) that organisms within populations vary in their traits. Be- cause most insects, weeds, and microbes can occur in huge numbers, it is likely that a small fraction of individuals may by chance already have genes that enable them to metabolize and detoxify a pesticide (p. 213). These individuals will sur- vive exposure to the pesticide, while individuals without these genes will not. If an insect that is genetically resistant to an in- secticide survives and mates with other resistant individuals,

Pests attack crops1 Pesticide is applied2 Most pests are killed. A few with innate resistance survive

Survivors breed and produce a pesticide-resistant population

4 Pesticide is applied again5 Pesticide has little effect. New, more toxic, pesticides are developed

FIGURE 7.15  Through the process of natural selection (pp. 46–49), crop pests may evolve resistance to the poisons we apply to kill them. When a pesticide is applied to an outbreak of insect pests, it may kill all individuals except those few with an innate immunity, or resistance, to the poison (resistant individuals are colored red in the diagram). Those surviving individuals may establish a population with genes for resistance to the poison. Future applications of the pesticide may then be ineffective, forcing us to develop a more potent poison or an alternative means of pest control.

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(a) Before cactus moth introduction

(b) After cactus moth introduction

(a) Before cactus moth introduction

(b) After cactus moth introduction

FIGURE 7.16  In a classic case of biocontrol, larvae of the cactus moth, Cactoblastis cactorum, were used to clear non-native prickly pear cactus from millions of hectares of rangeland in Queensland, Australia. These photos from the 1920s show an Australian ranch before (a) and after (b) introduction of the moth.

pest control strategy, called biological control or biocontrol, operates on the principle that “the enemy of one’s enemy is one’s friend.” For example, parasitoid wasps (p. 67) are natu- ral enemies of many caterpillars. These wasps lay eggs on a caterpillar, and the larvae that hatch from the eggs feed on the caterpillar, eventually killing it. Parasitoid wasps are fre- quently used as biocontrol agents and have often succeeded in controlling pests and reducing chemical pesticide use.

One classic case of successful biological control is the in- troduction of the cactus moth, Cactoblastis cactorum, from Argentina to Australia in the 1920s to control invasive prickly pear cactus that was overrunning rangeland. Within just a few years, the moth managed to free millions of hectares of range- land from the cactus (FIGURE 7.16).

However, biocontrol approaches entail risks. Biocon- trol organisms are sometimes more difficult to manage than chemical controls, because they cannot be “turned off” once they are initiated. Further, biocontrol organisms have in some cases become invasive and harmed nontarget organisms. Following the cactus moth’s success in Australia, for exam-

ple, it was introduced in other countries to control non-native prickly pear. Moths introduced to Caribbean islands spread to Florida on their own and are now eating their way through rare native cacti in the southeastern United States. If these moths reach Mexico and the southwestern United States, they could decimate many native and economically impor- tant species of prickly pear there. Because of concerns about unintended impacts, researchers study biocontrol proposals carefully before putting them into action, and government regulators must approve these efforts.

Integrated pest management combines varied approaches to pest control As it became clear that both chemical and biocontrol approaches pose risks, agricultural scientists and farmers began developing more sophisticated strategies, trying to combine the best attributes of each approach. Integrated pest management (IPM) incorporates numerous techniques, including biocontrol, use of chemicals when needed, close monitoring of populations, habitat alteration, crop rotation, transgenic crops, alternative tillage methods, and mechani- cal pest removal.

IPM has become popular in many parts of the world that are embracing sustainable agriculture techniques. Indone- sia stands as an exemplary case. This nation had subsidized pesticide use heavily for years, but its scientists came to un- derstand that pesticides were actually making pest problems worse. They were killing the natural enemies of the brown planthopper, which began to devastate rice fields as its popu- lations exploded. Concluding that pesticide subsidies were costing money, causing pollution, and apparently decreas- ing yields, the Indonesian government in 1986 banned the import of 57 pesticides, slashed pesticide subsidies, and pro- moted IPM. Within just four years, pesticide production fell by half, imports fell by two-thirds, and subsidies were phased out (saving $179 million annually). Rice yields rose 13% with IPM, and since then the approach has spread to dozens of other nations.

Pollinators are beneficial “bugs” worth preserving Managing insect pests is such a major issue in agriculture that it is easy to fall into a habit of thinking of all insects as somehow bad or threatening. But in fact, most insects are harmless to agriculture, and some are absolutely essential. The insects that pollinate crops are among the most vital, yet least understood and appreciated, factors in our food pro- duction (FIGURE 7.17). Pollinators are the unsung heroes of agriculture.

Pollination (p. 68) is the process by which male sex cells of a plant (pollen) fertilize female sex cells of a plant; it is the botanical version of sexual intercourse. Pollinators are ani- mals that move pollen from one flower to another. Flowers are, in fact, evolutionary adaptations that function to attract pollinators. The sugary nectar and protein-rich pollen in flow- ers serve as rewards to lure these sexual intermediaries, and the sweet smells and bright colors of flowers are signals to ad- vertise these rewards.

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Foods can be genetically modified The genetic modification of crops and livestock is one type of genetic engineering. Genetic engineering is any process whereby scientists directly manipulate an organism’s genetic material in the laboratory by adding, deleting, or changing segments of its DNA (p. 28). Genetically modified (GM) or- ganisms are organisms that have been genetically engineered using recombinant DNA, which is DNA that has been patched together from the DNA of multiple organisms (FIGURE 7.18).

Our staple grain crops are derived from grasses and are wind-pollinated, but 800 types of cultivated plants rely on bees and other insects for pollination. Overall, native species of bees in the United States alone are estimated to provide $3 billion of pollination services each year to crop agriculture.

Preserving the biodiversity of native pollinators is espe- cially important today because the domesticated workhorse of pollination, the honeybee (Apis mellifera), is in decline. In recent years, two accidentally introduced parasitic mites have swept through honeybee populations, decimating hives and pushing many beekeepers toward financial ruin. On top of this, starting in 2006, entire hives inexplicably began dy- ing off. In each of the last several years, up to one-third of all honeybees in the United States have vanished from what is being called colony collapse disorder. Scientists are racing to discover the cause of this mysterious syndrome. Leading hy- potheses are insecticide exposure, an unknown new parasite, or a combination of stresses that weaken bees’ immune sys- tems and destroy social communication within the hive. We must be very careful when trying to control the “bad” bugs that threaten the plants we value so that we do not kill the “good” insects as well.

GENETICALLY MODIFIED FOOD The Green Revolution enabled us to feed a greater number and proportion of the world’s people, but relentless popula- tion growth is demanding still more innovation. A new set of potential solutions began to arise in the 1980s and 1990s as advances in genetics enabled scientists to directly alter the genes of organisms, including crop plants and livestock. The genetic modification of organisms that provide us food holds promise to enhance nutrition and the efficiency of agricul- ture while lessening impacts on the planet’s environmental systems. However, genetic modification may also pose risks that are not yet well understood. This possibility has given rise to anxiety and protest by consumer advocates, small farmers, environmental activists, and critics of big business.

FIGURE 7.17  North American farmers hire beekeepers to bring hives (in white boxes in photo) of European honeybees (inset, on ap- ple blossom) to their crops when it is time for flowers to be pollinated. Recently, honeybees have suffered devastating epidemics, making it increasingly important to conserve native species of pollinators.

DNA

Nucleus

Bacterial chromosome

Bacterium Cell from

another organism

Recombinant DNA

Gene of interest

Plasmid

Bacterium with recombinant plasmid

Cell division and reproduction

Gene transfer to target organism

1 2

FIGURE 7.18  To create recombinant DNA, scientists first isolate plasmids ➊ small circular DNA molecules, from a bacte- rial culture. DNA containing a gene of interest ➋ is then removed from another organism. Scientists insert the gene of interest into the plasmid to form recombinant DNA ➌. This recombinant DNA enters new bacteria ➍, which then reproduce ➎, generating many copies of the desired gene. The desired gene is then transferred to many individuals of the target plant or animal ➏. The individuals that successfully incorporate the desired gene are then cultured and grown. If all goes as planned, the new gene will be expressed in the genetically modified organism as a desirable trait, such as rapid growth or high nutritional content in a food crop.

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differ from traditional selective breeding in several ways. For one, selective breeding mixes genes from individuals of the same or similar species, whereas scientists creating recom- binant DNA routinely mix genes of organisms as different as viruses and crops, or spiders and goats. For another, selec- tive breeding deals with whole organisms living in the field, whereas genetic engineering works with genetic material in the lab. Third, traditional breeding selects from combinations of genes that come together on their own, whereas genetic engineering creates the novel combinations directly. Thus, traditional breeding changes organisms through the process of selection (pp. 46–49), whereas genetic engineering is more akin to the process of mutation (p. 47).

Biotechnology is transforming the products around us In just three decades, GM foods have gone from science fic- tion to mainstream agriculture. Most GM crops today are engineered to resist herbicides, so that farmers can apply

The goal is to place genes that produce certain proteins and code for certain desirable traits (such as rapid growth, disease resistance, or high nutritional content) into organisms lacking those traits. An organism that contains DNA from another species is called a transgenic organism, and the genes that have moved between them are called transgenes.

The creation of transgenic organisms is one type of biotechnology, the material application of biological science to create products derived from organisms. Biotechnology has helped us develop medicines, clean up pollution, under- stand the causes of cancer and other diseases, dissolve blood clots after heart attacks, and make better beer and cheese. FIGURE 7.19 shows several notable developments in GM foods. The stories behind them illustrate both the promises and pit- falls of food biotechnology.

The genetic alteration of plants and animals by people is nothing new; through artificial selection (p. 48) we have in- fluenced the genetic makeup of our livestock and crop plants for thousands of years. However, as critics are quick to point out, the techniques geneticists use to create GM organisms

Several Notable Examples of Genetically Modified Food Technology

Golden rice

Ice-minus strawberries

Bt crops

Food FoodDevelopment

StarLink corn

Sunflowers and superweeds

Millions of people in the developing world get too little vitamin A in their diets, causing diarrhea, blindness, immune suppression, and even death. The problem is worst with children in east Asia, where the staple grain, white rice, contains no vitamin A. Researchers took genes from plants that produce vitamin A and spliced the genes into rice DNA to create more-nutritious “golden rice” (the vitamin precursor gives it a golden color). Critics charged that biotech companies over-hyped their product.

Researchers removed a gene that facilitated the formation of ice crystals from the DNA of a bacterium, Pseudomonas syringae. The modified, frost-resistant bacteria could then serve as a kind of antifreeze when sprayed on the surface of crops such as strawberries, protecting them from frost damage. However, news coverage of scientists spraying plants while wearing face masks and protective clothing caused public alarm.

By equipping plants with the ability to produce their own pesticides, scientists hoped to reduce crop losses from insects. Scientists working with Bacillus thuringiensis (Bt) pinpointed the genes responsible for producing that bacterium’s toxic effects on insects, and inserted the genes into the DNA of crops. The USDA and EPA approved Bt versions of 18 crops for field testing, from apples to broccoli to cranberries. Corn and cotton are the most widely planted Bt crops today. Proponents say Bt crops reduce the need for chemical pesticides. Critics worry that they induce insects to evolve resistance to the toxins, cause allergic reactions in people, and harm nontarget species.

Research on Bt sunflowers suggests that transgenes might spread to other plants and turn them into vigorous weeds that compete with the crop. This is most likely to happen with crops like squash, canola, and sunflowers that can breed with their wild relatives. Researchers bred wild sunflowers with Bt sunflowers and found that hybrids with the Bt gene produced more seeds and suffered less herbivory than hybrids without it. They concluded that if Bt sunflowers were planted commercially, the Bt gene might spread and turn wild sunflowers into superweeds.

StarLink corn, a variety of Bt corn, had been approved and used in the United States for animal feed but not for human consumption. In 2000, StarLink corn DNA was discovered in taco shells and other corn products. These products were recalled amid fears of allergic reactions. No such health effects were confirmed, but the corn’s manufacturer chose to withdraw the product from the market.

The Monsanto Company’s widely used herbicide, Roundup, kills weeds, but it kills crops too. So, Monsanto engineered soybeans, corn, cotton, and canola to withstand the effects of its herbicide. With these “Roundup Ready crops,” farmers can spray Roundup without killing their crops. Of course, this also creates an incentive for farmers to use Roundup rather than a competing brand. Unfortunately, Roundup’s active ingredient, glyphosate, is a leading cause of illness for California farm workers, and weeds are starting to evolve resistance to glyphosate.

Roundup Ready crops

OH OH

C P N

H H

C C

Development

FIGURE 7.19  As genetically modified foods were developed, a number of products ran into public opposition or trouble in the marketplace. A selection of such cases serves to illustrate some of the issues that proponents and opponents of genetically modified foods have been debating.

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(FIGURE 7.20B). The market value of GM crops in 2009 was estimated at $10.5 billion.

What are the impacts of GM crops? As GM crops were adopted and as biotech business ex- panded, many citizens, scientists, and policymakers became concerned. Some feared the new foods might be dangerous for people to eat. Others worried that pests would evolve re- sistance to the supercrops and become “superpests” or that transgenes would be transferred from crops to other plants and turn them into “superweeds.” Some worried that trans- genes might become integrated into closely related wild rela- tives of crops.

Because GM technology is rapidly changing, and because its large-scale introduction into our environment is recent, there remains much that we don’t yet know. Millions of Americans eat GM foods every day without outwardly obvi- ous signs of harm, and direct evidence for negative ecological effects is limited so far. However, it is still too early to dismiss concerns about environmental impacts without further scien- tific research.

Data indicate that the effect of GM crops on pesticide use has been mixed. The adoption of insect-resistant GM crops appears to reduce the use of chemical insecticides, but farmers planting herbicide-tolerant crops tend to use more herbicide because their crops can withstand it. A 2010 study by the Institute of Science in Society calculated that as GM crops expanded in the United States between 1996 and 2008, insecticide use declined by 64 million pounds, but herbicide use increased by 383 million pounds.

Genetically modified crops have the potential to ad- vance agriculture sustainably by promoting no-till farming with herbicide-resistant crops, engineering crops with high drought tolerance for use in arid regions, and developing high-yield crops that can feed our growing population with- out converting additional natural areas to agriculture.

However, GM crops are expensive to create, and crops with traits that might benefit poor, small-scale farmers of de- veloping countries (such as increased nutrition, drought tol- erance, and salinity tolerance) have not been widely commer- cialized, perhaps because corporations have less economic incentive to do so. Often, a company’s GM crops are tolerant to herbicides that the same company manufactures and prof- its from (e.g., Monsanto’s Roundup Ready crops). Whereas the Green Revolution was a largely public venture, the “gene revolution” promised by GM crops is largely driven by the fi- nancial interests of corporations selling proprietary products. This has driven widespread concern that the global food sup- ply is being dominated by a few large agrobiotech corpora- tions that develop GM technologies.

The future of GM foods seems likely to hinge on social, economic, legal, and political factors as well as scientific ones—and these factors vary in different nations. European consumers have expressed widespread unease about GM tech- nologies, and European governments mandate that all foods containing GM organisms be labeled as such. In contrast, U.S. consumers have largely accepted the GM crops approved by U.S. agencies, generally without even realizing that the major- ity of their food contains GM products.

herbicides to kill weeds without having to worry about killing their crops. Other crops are engineered to resist insect attack. Some are modified for both types of resistance. Resistance to herbicides and pests enables large-scale commercial farmers to grow crops more efficiently. As a result, sales of GM seeds to these farmers in the United States and other countries have risen quickly.

In 2010, GM varieties comprised 86% of the U.S. corn harvest and 93% of the soybean and cotton crops. This is incredible growth, considering that GM crop varieties have been commercially planted only since 1996. Worldwide, three of every four soybean plants are now transgenic, as is one of every four corn plants, one of every five canola plants, and half of all cotton plants. Given the diversity of foods that contain corn products and the overwhelming majority of the U.S. corn crop that is GM varieties, it is extremely likely that you consume GM foods on a daily basis.

Soybeans account for most of the world’s GM crops ( FIGURE 7.20A). Of the 29 nations growing GM crops in 2010, six (the United States, Brazil, Argentina, India, Can- ada, and China) accounted for 92% of production, with the United States alone growing nearly half the global total

(a) GM crops by type

(b) GM crops by nation

Argentina (15.5%)

China (2.4%)

India (6.4%)

Canada (5.9%)

Brazil (17.2%)

23 other nations (7.5%)

Soybeans (50%)

C an

o la (5

% )

Cotton (14%)

Corn (31%)

United States (45.1%)

FIGURE 7.20  Of the world’s genetically modified crops (a), soybeans constitute the majority so far. Of the world’s nations (b), the United States devotes the most land area to GM crops. Data are for 2010, from the International Service for the Acquisition of Agri-Biotech

Applications.

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as much as 90% is used up in cellular respiration. For this reason, eating meat is far less energy-efficient than relying on a vegetarian diet and leaves a far greater ecological footprint.

Some animals convert grain feed into milk, eggs, or meat more efficiently than others (FIGURE 7.22). Scientists have cal- culated relative energy-conversion efficiencies for different types of animals. Such energy efficiencies have ramifications for land use because land and water are required to raise food for the animals, and some animals require more than others. FIGURE 7.23 shows the area of land and weight of water re- quired to produce 1 kg (2.2 lb) of food protein for milk, eggs, chicken, pork, and beef. Producing eggs and chicken meat requires the least space and water, whereas producing beef requires the most. Such differences make clear that when we choose what to eat, we are also indirectly choosing how to make use of resources such as land and water.

Feedlot agriculture has benefits and costs In traditional agriculture, livestock are kept by farming families near their homes or are grazed on open grasslands by nomadic herders or sedentary ranchers. These traditions

The world’s large, rapidly industrializing nations (such as Brazil, India, and China) are now aggressively pursuing GM crops, even as ethical, economic, and political debates over the costs and benefits of these foods continue. Although many ex- perts feel we should adopt the precautionary principle (the idea that one should not undertake new action until the rami- fications of that action are well understood) and proceed with caution on GM foods, the demands placed on food supplies by a growing human population may accelerate their adoption around the world.

RAISING ANIMALS FOR FOOD: LIVESTOCK, POULTRY, AND AQUACULTURE Food from cropland agriculture makes up a large portion of the human diet, but most of us also eat animal products. Just as farming methods have changed over time, so have the ways we raise animals for food.

As wealth and global commerce have increased, so has humanity’s consumption of meat, milk, eggs, and other ani- mal products (FIGURE 7.21). The world population of domes- ticated animals raised for food rose from 7.2 billion animals to 25.2 billion animals between 1961 and 2009. Most of these animals are chickens. Global meat production has increased fivefold since 1950, and per capita meat consumption has doubled. The United Nations Food and Agriculture Organi- zation (FAO) estimates that as more developing nations go through the demographic transition (pp. 122–123) and be- come wealthier, total meat consumption will nearly double by the year 2050.

Our food choices are also energy choices What we choose to eat has ramifications for how we use en- ergy and the land that supports agriculture. Recall our dis- cussions of trophic levels and pyramids of energy (pp. 68–71). Every time energy moves from one trophic level to the next,

Produce output (edible weight)

Feed input

20.0 kg

7.3 kg

4.5 kg

2.8 kg

1.1 kg

1 kg

Beef

Pork

Eggs

Chicken

Milk

1 kg

FIGURE 7.22  Different animal food products require different amounts of input of animal feed. Chickens must be fed 2.8 kg of feed for each 1 kg of resulting chicken meat, for instance, whereas 20 kg of feed must be provided to cattle to produce 1 kg of beef. Data from Smil, V., 2001. Feeding the world: A challenge for the twenty-first century. Cambridge, MA: MIT Press.

W o rl d m

ea t

an d s

ea fo

o d p

ro d u

ct io

n (k

g p

er p

er so

n p

er y

ea r)

19 60

19 65

19 70

19 75

19 80

19 85

19 90

19 95

20 00

20 05

20 08

Year

Meat

Seafood

FIGURE 7.21  Per capita consumption of meat from farmed animals has risen steadily worldwide, as has per capita consump- tion of seafood (marine and freshwater, harvested and farmed). Data from U.N. Food and Agriculture Organization (FAO).

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Beef (245.0 m2)

Beef (750 kg)

Pork (175 kg)

Milk (250 kg)

Eggs (15 kg)

Pork (90.0 m2)

Milk (23.5 m2)

Eggs (22.0 m2)

Chicken (14.0 m2)

Chicken (50 kg)

(a) Land required to produce 1 kg of protein

(b) Water required to produce 1 kg of protein

FIGURE 7.23  Producing different types of animal products requires different amounts of land and water. Raising cattle for beef requires by far the most land and water of all animal products. Data from Smil, V., 2001. Feeding the world: A challenge for the twenty-first century. Cambridge, MA: MIT Press.

Today nearly half the world’s pork and most of its poultry come from feedlots.

Feedlot operations allow for economic efficiency and greater food production, which makes meat affordable to more people. Feedlots also offer one overarching benefit for environmental quality: Taking cattle and other livestock off rangeland and concentrating them in feedlots reduces the grazing impacts they would otherwise exert across large por- tions of the landscape.

Intensified animal production through the industrial feedlot model has some negative effects, though. Forty-five percent of our global grain production goes to feed livestock and poultry. This elevates the price of staple grains and endangers food security for the very poor. Livestock produce prodigious amounts of manure and urine, and their waste can pollute surface water and groundwater. The crowded conditions under which animals are often kept necessitate heavy use of antibiotics to control disease. The overuse of antibiotics can cause microbes to become resistant to the an- tibiotics (just as pests become resistant to pesticides; p. 147), making these drugs less effective. Livestock are also a ma- jor source of greenhouse gases that lead to climate change (pp. 300-301). A comprehensive FAO report in 2006 con- cluded that livestock agriculture contributes 9% of our car- bon dioxide emissions, 37% of our methane emissions, and 65% of our nitrous oxide emissions—altogether, 18% of the emissions driving climate change, a larger share than auto- mobile transportation!

Proper management of feedlots can minimize their impacts, however, and both the EPA and the states regulate U.S. feedlots. Manure from feedlots, for example, can be applied to cropland as a fertilizer, reducing the need for inor- ganic fertilizer.

We raise seafood with aquaculture Besides growing plants as crops and raising animals on rangelands and in feedlots, we rely on aquatic organisms for food. Wild fish populations are plummeting throughout the world’s oceans as increased demand and new technologies have led us to overharvest most marine fisheries (pp. 273– 275). This means that raising fish and shellfish on “fish

(a) Chicken factory farm in Arkansas (b) Cattle feedlot in California

FIGURE 7.24  Most meat eaten in the United States comes from animals raised in feedlots, or factory farms. These locations house thousands of chickens (a) or cattle (b) at high densities. The animals are dosed liberally with antibiotics to control disease.

survive, but the advent of industrial agriculture has brought a new method. Feedlots, also known as factory farms or con- centrated animal feeding operations (CAFOs), are essentially huge warehouses or pens designed to deliver energy-rich food to animals living at extremely high densities (FIGURE 7.24).

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ple, could introduce genes into wild salmon populations or spread disease if they were to escape from aquaculture facilities.

THE GROWTH OF SUSTAINABLE AGRICULTURE Industrial agriculture has allowed food production to keep pace with our growing population, but it involves many ad- verse environmental and social impacts. These range from the degradation of soils to reliance on fossil fuels to problems arising from pesticide use, genetic modification, and inten- sive feedlot and aquaculture operations. Although intensive commercial agriculture may help alleviate certain environ- mental pressures, it often worsens others. Throughout this chapter, we have seen sustainable approaches to agriculture that maintain high crop yields, minimize resource inputs into food production, and lessen the environmental impacts of farming. Let’s now take a closer look at the growth of sus- tainable agriculture around the world.

Organic agriculture is booming One type of sustainable agriculture is organic agriculture, which is agriculture that uses no synthetic fertilizers, insect- icides, fungicides, or herbicides. In 1990, the U.S. Congress passed the Organic Food Production Act to establish national standards for organic products and facilitate their sale. Un- der this law, in 2000 the USDA issued criteria by which crops and livestock could be officially certified as organic, and these standards went into effect in 2002 as part of the National Or- ganic Program. California, Washington, and Texas established stricter state guidelines for labeling foods organic, and today many U.S. states and over 70 nations have laws spelling out or- ganic standards.

For farmers, organic farming can bring a number of benefits: lower input costs, enhanced income from higher- value produce, and reduced chemical pollution and soil deg- radation (see THE SCIENCE BEHIND THE STORY, pp. 156–157). Transitioning to organic agriculture does involve some risk, however, as farmers must use organic approaches for three years before their products can be certified as organic and sold at prices commanded by organic foods. The main obstacle for consumers to organic foods is price. Organic products tend to be 10–30% more expensive than conventional ones, and some (such as milk) can cost twice as much. However, enough consumers are willing to pay more for organic products that grocers and other businesses are making them more widely available.

Today, three of four Americans buy organic food at least occasionally, and more than four of five retail groceries offer it. U.S. consumers spent $26.7 billion on organic food in 2010, amounting to 4% of all food sales (FIGURE 7.26A). Worldwide, sales of organic food tripled between 2000 and 2009, when sales surpassed $54 billion.

Production is increasing along with demand (FIGURE 7.26B). Although organic agriculture takes up less than 1%

farms” may be the only way to meet our growing demand for these foods.

We call the cultivation of aquatic organisms for food in controlled environments aquaculture, and people pursue aquaculture with over 220 freshwater and marine species ( FIGURE 7.25). Many aquatic species are grown in open water in large, floating net-pens. Others are raised in ponds or holding tanks. Aquaculture is the fastest-growing type of food production; in the past 20 years, global output has in- creased fivefold. Most widespread in Asia, aquaculture today produces $80 billion worth of food and provides three- quarters of the freshwater fish and over half of the shellfish that we eat.

Aquaculture helps reduce fishing pressure on overhar- vested and declining wild stocks. Furthermore, aquacul- ture consumes fewer fossil fuels and provides a safer work environment than does commercial fishing. Fish farming can also be remarkably energy-efficient, producing as much as 10 times more fish per unit area than is harvested from waters of the continental shelf and up to 1,000 times more than is har- vested from the open ocean.

Along with its benefits, aquaculture has disadvantages. Aquaculture can produce prodigious amounts of waste, both from the farmed organisms and from the feed that goes uneaten and decomposes in the water. Like feedlot animals, commercially farmed fish often are fed grain, and this affects food supplies for people. In other cases, farmed fish are fed fish meal made from wild ocean fish such as herring and anchovies, whose harvest may place additional stress on wild fish populations.

If farmed aquatic organisms escape into ecosystems where they are not native (as several carp species have done in U.S. waters), they may spread disease to native stocks or may outcompete native organisms for food or habitat. Salmon genetically modified for rapid growth, for exam-

Other aquatic animals (2.6%)

Crustaceans (7.4%)

Fish (48.0%)

Aquatic plants (22.3%)

Molluscs (19.7%)

FIGURE 7.25  Aquaculture involves many types of fish, but also a wide diversity of other marine and freshwater organisms. Data from U.N. Food and Agriculture Organization (FAO).

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The average grocery store item travels 1,400 miles from its origin to your shopping cart.

This long-distance transport consumes oil and contributes to pollution and climate change.

Locally grown produce and locally made products cut down on the carbon footprint of our food.

You Can Make a Difference

Partner with farmers in community-supported agriculture programs.

Ask your campus’s food services director to buy locally grown produce and locally made products.

Shop at farmer’s markets, or help to start one on campus.

E n

v isio

n it

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T H

E S

C IE

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E B

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T O

R Y

at Therwil, Switzerland, established back in 1977. Long-term studies are rare and valuable in agriculture and in ecology, because they can reveal slow processes or subtle effects that get swamped out by variation in shorter- term studies.

At the Swiss research site, wheat, potatoes, and other crops are grown in plots cultivated in different treatments:

▶ Conventional farming using large amounts of chemical pesticides, her- bicides, and inorganic fertilizer

▶ Conventional farming that also uses organic fertilizer (cattle manure)

▶ Organic farming using only manure, mechanical weeding, and plant ex- tracts to control pests

▶ Organic farming that also adds natu- ral boosts, such as herbal extracts in compost

Researchers record crop yields at harvest each year. They analyze the soil regularly, measuring nutrient content, pH, structure, and other vari- ables. They also measure the biologi- cal diversity and activity of microbes and invertebrates in the soil. Such indicators of soil quality help research- ers assess the potential for long-term farm productivity.

In 2002, Paul Mäder and col- leagues from two Swiss research insti- tutes reported in the journal Science results from 21 years of data. Over this time, the organic fields yielded 80% of what the conventional fields produced. Organic crops of winter wheat yielded 90% of the conventional yield. Organic potato crops averaged 58–66% of conventional yields because of nutrient deficiency and disease.

Although the organic plots pro- duced 20% less, they did so while re- ceiving 35–50% less fertilizer than the

conventional fields and 97% fewer pes- ticides. Thus, Mäder’s team concluded, the organic plots were highly efficient and represent “a realistic alternative to conventional farming systems.”

How can organic fields produce decent yields without synthetic agricultural chemicals? The answer lies in the soil. Mäder’s team found that soil in the organic plots had better structure, better supplies of some nutrients, and much more microbial activity and invertebrate biodiversity (first figure). Differences were visible just by looking at the fields (second figure).

The Swiss data reflect those found by scientists elsewhere. For instance, U.S. researchers compar- ing organic and conventional farms in North Dakota and Nebraska found that organic farming produced soils with more microbial life, earthworm activity, water-holding capacity,

Dr. Paul Mäder, Research Institute of Organic Agriculture, Switzerland

T H E S C I E N CE B E H I N D T H E S TO RY

Does Organic Farming Work?

Organic farming puts fewer synthetic chemicals into the soil, air, and water, but can it produce large enough crop yields to feed the world’s people?To search for the answer we can turn to Switzerland, a leader in organic farming. One in every nine hectares of agricultural land here is managed organically—the fourth-highest rate in the world—and Swiss scientists have taken the lead in examining the benefits and costs of organic farming. The longest-run- ning and most-cited studies of organic agriculture come from experimental farms

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topsoil depth, and naturally occurring nutrients. Given such differences in soil quality, research- ers expect that organic fields should perform better and better relative to conventional fields as time goes by—in other words, that they are more sustainable.

Studies are continuing at the Swiss plots to determine whether this is true. As one example, in 2009, Jens Leifeld and two colleagues at a Zurich research institute analyzed soil carbon content after 27 years. They found that soil carbon had decreased in all the treatments, but that it had declined most in conventional plots using inorganic fertilizer or no fertilizer.

Conventional plots that supplemented synthetic fertilizer with cow manure, however, did just as well as the organic plots in retaining soil carbon (third figure).

As more long-term data are published and new studies begin, we are learning more and more about the benefits of organic agriculture for soil quality and about how we might improve conventional methods to maximize crop yields while protect- ing the long-term sustainability of agriculture.

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Organic fields outperformed con- ventional fields supplemented with manure in their soil quality, includ- ing averaged values for soil chem- istry (six variables), soil structure (three variables), soil invertebrates (five variables), and microbial activ- ity (six variables). Organic fields outperformed conventional fields without manure (not shown) still more. Data from Mäder, P., et al., 2002. Soil fertility and biodiversity in organic farming. Science 296: 1694–1697.

(a) Organic plot

(b) Conventional plot

Organic plots (a) showed more weeds but more earthworm cast- ings and healthier soil structure than conventional plots (b) in the Swiss experiment.

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Organic plots lost less soil carbon over 27 years of farming than did conventional plots with no fertilizer or only synthetic fertilizer. Conven- tional plots with organic fertilizer supplements retained just as much soil carbon as the organic plots. Data from Leifeld, J., et al., 2009. Consequences of conventional versus organic farming on soil carbon: Results from a 27-year field experiment. Agronomy Journal 101: 1204–1218.

of agricultural land worldwide (35 million ha, or 86.5 million acres, in 2008), this area is rapidly expanding. Two-thirds of this area is in developed nations, and farmers in all 50 U.S. states and 1.4 million farmers in more than 150 nations prac- tice organic farming commercially to some extent. Contrary to common misconception, organic farming can be per- formed on both big and small farms, as long as the criteria for organic certification are satisfied.

Government policies have aided organic farming. In the United States, the 2008 Farm Bill set aside $112 million over five years for organic agriculture, and the government helps to defray certification expenses. The European Union adopted a policy in 1993 to support farmers financially during con- version to organic agriculture. Once conversion is complete, studies suggest that reduced inputs and higher market prices can make organic farming at least as profitable for the farmer as conventional methods.

FIGURE 7.26  Sales of organic food in the United States (a) have increased rapidly in the past decade, both in total dollar amounts (bars) and as a percent- age of the overall food market (line). Since the mid- 1990s in the United States (b), acreage devoted to organic crops and livestock has each quadrupled, and the number of certified operations has more than tri- pled. (a) Adapted by permission from Willer, Helga, and Lukas Kilcher (Eds.), (2009). The world of organic agriculture, statistics

and emerging trends 2009. FiBL-IFOAM Report. IFOAM, Bonn; FiBL, Frick; ITC, Geneva. Data used with permission from

Organic Trade Association OTA: Manufacturer Survey 2007.

Additional, updated data provided by Organic Trade Associa-

tion. (b) Data from USDA Economic Research Service.

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out North America as people rediscover the joys of fresh, locally grown produce. At farmers’ markets, consumers buy meats and fresh fruits and vegetables in season from local producers. These markets generally offer a wide choice of organic items and unique local varieties not found in supermarkets.

Some consumers are even partnering with local farmers in a phenomenon called community-supported agriculture (CSA). In a CSA program, consumers pay farmers in advance for a share of their yield, usually a weekly delivery of produce. Consumers get fresh seasonal produce, and farmers get a guaranteed income stream up front to invest in their crops—a welcome alternative to taking out loans and being at the mer- cy of the weather.

Sustainable agriculture provides a roadmap for the future The best approach for making an agricultural system sustainable is to mimic the way a natural ecosystem functions. Ecosystems are sustainable because they operate in cycles and are internally stabilized with negative feedback loops. In this way they pro- vide a useful model for agriculture.

The approaches embraced by the Schroeder brothers and Nate Ronsiek exemplify how agricultural systems can be more efficiently integrated with surrounding natural ecosystems and reduce the environmental impacts from food production. Efforts like these, together with other approaches farmers around the world are taking to help make agriculture sustain- able, will be crucial for all of us as we progress through the coming century.

Locally supported agriculture is growing Apart from organic methods, another component of the move toward sustainable agriculture is an attempt to reduce fossil fuel use from the long-distance transport of food (see ENVISIONIT, p. 155). The average food product sold in a U.S. supermarket travels at least 2,300 km (1,400 mi) between the farm and the grocery. Because of the travel time, supermar- ket produce is often chemically treated to preserve freshness and color.

In response, increasing numbers of farmers and con- sumers in developed nations are supporting local small-scale agriculture. Farmers’ markets are springing up through-

Do You Want Your Food Labeled? The USDA issues labels to certify that products claiming to be organic have met the government’s organic standards. Critics of genetically modi-

fied food want GM products to be labeled as well. Given that well over 70% of processed food now contains GM ingredients, labeling would add costs. Yet the European Union currently labels such foods. Do you want your food to be labeled to indicate whether it is organic or geneti- cally modified? Would you choose among foods based on such labeling? How might your food choices and purchas- ing decisions have environmental impacts (good or bad)?

Our species has a 10,000-year history with agriculture, and over this time methods of food production have changed substantially. Many practices of intensive industrial agricul- ture exert substantial negative environmental impacts. At the same time, the increased production had boosted food supplies and helped to relieve certain pressures on land or resources.

What is certain is that if our planet is to support 9 billion people by mid-century without further degrading

the soil, water, pollinators, and other resources and ecosys- tem services that support our food production, we must find ways to shift to sustainable agriculture. Approaches such as biological pest control, organic agriculture, pollinator con- servation, preservation of native crop diversity, sustainable aquaculture, and likely some degree of careful and responsi- ble genetic modification of food may all be parts of the game plan we will need to set in motion to achieve a sustainable future.

➤ CONCLUSION

T E S T I N G Y O U R C O M P R E H E N S I O N

1. Describe patterns in global food security from 1970 to 2010. Name two nutritional deficiencies commonly seen in the modern world.

2. Compare and contrast the methods used in traditional and industrial agriculture. How does sustainable agri- culture differ from industrial agriculture?

3. How are soil horizons created? List and describe the major horizons in a typical soil profile. What is the gen- eral pattern of distribution of organic matter in a typical profile?

4. Name three human activities that can promote soil ero- sion. Describe several farming techniques (such as ter- racing and no-till farming) that can help reduce the risk of erosion.

5. Explain how over-irrigation can damage soils and reduce crop yields.

6. How do fertilizers boost crop growth? How can large amounts of fertilizer added to soil also end up in water supplies and the atmosphere? How do sustainable agri- culture approaches reduce fertilizer runoff?

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S E E K I N G S O L U T I O N S 1. How do you think a farmer can best help to conserve

soil? How do you think a scientist can best help to con- serve soil? How do you think a national government can best help to conserve soil?

2. Assess several ways in which high-input industrial agri- culture can be beneficial for the environment and several ways in which it can be detrimental. Now suggest several ways in which we might modify industrial agriculture to mitigate its environmental impacts.

3. What factors make for an effective biological control strategy of pest management? What risks are involved in biocontrol? If you had to decide whether to use biocon- trol against a particular pest, what questions would you want to have answered before you decide?

4. THINK IT THROUGH You are the head of an inter- national granting agency that assists farmers with soil conservation and sustainable agriculture. You have $10

million to disburse. Your agency’s staff has decided that the funding should go to (1) farmers in an arid area of Africa prone to salinization, (2) farmers in a fast-growing area of Indonesia where swidden agriculture is practiced, (3) farmers in Argentina practicing no-till agriculture, and (4) farmers in a dryland area of Mongolia undergo- ing desertification. What types of projects would you recommend funding in each of these areas, how would you apportion your funding among them, and why?

5. THINK IT THROUGH You are a USDA official and must decide whether to allow the planting of a new ge- netically modified strain of cabbage that produces its own pesticide and has twice the vitamin content of regu- lar cabbage. What questions would you ask of scientists before deciding whether to approve the new crop? What scientific data would you want to see? Would you also consult nonscientists or consider ethical, economic, and social factors?

C A L C U L A T I N G E C O L O G I C A L F O O T P R I N T S As food production became more industrialized during the 20th century, more and more energy has been expended to store food and ship it to market. In the United States today, food travels an average of 1,400 miles from the field to your table. The price you pay for the food covers the cost of this long-distance transportation, which in 2004 was approximately $1 per ton per mile. Assuming that the aver- age person eats 2 pounds of food per day, calculate the food transportation costs for each category in the table below.

7. Explain how pesticide resistance occurs. 8. How is a transgenic organism created? How is genetic

engineering different from traditional agricultural breed- ing? How is it similar?

9. Compare and contrast the land and water required to produce 1 kg of beef, pork, chicken, eggs, and milk.

10. What are some economic benefits of aquaculture? What are some negative environmental impacts?

Consumer Daily cost Annual cost You $1.40 $511 Your class

Your town

Your state

United States

Pirog, R., and A. Benjamin, 2003. Checking the food odometer: Comparing food miles for local versus conventional produce sales to Iowa institutions. Leopold Center for Sustainable Agriculture, Iowa State University, Ames.

1. What specific challenges to environmental sustainabil- ity are imposed by a food production and distribution system that relies on long-range transportation to bring food to market?

2. A 2003 study noted that locally produced food traveled only 50 miles or so to market, thus saving 96% of the transportation costs. Locally grown foods may be fresher and cause less environmental impact as they are brought to market, but what are the disadvantages to you as a consumer in relying on local food production? Do you think the advantages outweigh those disadvantages?

3. What has happened to gasoline prices recently? How would future increases in the price of gas affect your an- swers to the preceding questions?

Go to www.masteringenvironmentalscience.com for homework assignments, practice quizzes, Pearson eText, and more.

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