Precis 3

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I n the catalog of global environmental insults, extinctions stand out as irre- versible. Current rates are high and ac-

celerating (1). After a recent conference (2), we concluded that preventing extinc- tions is practical, but requires innovative measures. Enforceable protection of re- maining natural ecosystems is an overar- ching recommendation. Our deliberations regarding the implementation of this led us to attempt to answer a number of ques- tions. The answers outlined here represent, if not consensus, then the opinion of the majority. Supplementary material summa- rizes unresolved debates (3).

Is Saving Remaining Biodiversity Still Possible? Globally, the harm we inflict on biodiversi- ty often stems from impacts on vulnerable, biodiverse areas that contribute relatively little to overhall human well-being and of- ten diminish it. For example, tropical hu- mid forests house two-thirds of terrestrial species (4). Within half a century, tropical forests have shrunk by half, a loss of 9 mil- lion km2 (5), with several times more forest damaged than cleared each year (6). Yet clearing tropical forests has created only ~2 million km2 of the planet’s 15 million km2 of croplands (7). The poor soils under- lying many tropical forests soon degrade and are abandoned or contribute only marginally to the global livestock produc- tion (7, 8). About 10% of these cleared forests are on steep mountain slopes where high rainfall has predictably tragic conse- quences to those who settle there (8).

The Amazon, the Congo, and rivers in Southeast Asia hold almost half the world’s freshwater fish species. Their fates depend on the surrounding forest watersheds. Else- where, most accessible rivers are dammed

and channeled (9), causing their faunas to be more threatened than terrestrial ones (10). Diversion of water for irrigation threatens ecosystems, such as the Mesa Central (Mex- ico) and the Aral Sea and its rivers (Central Asia). Irrigation projects are often economic disasters (11, 12), as salt accumulation quickly destroys soil fertility (13).

Fishing contributes only 5% of the glob- al protein supply, yet is the major threat to the oceans’ biodiversity. The multitude of fish species caught on coral reefs constitutes only a small, though poorly known, fraction of the total catch, but f isheries severely damage these most diverse marine ecosys- tems. Most major fish stocks are overfished (14); thus, mismanagement diminishes our welfare and biodiversity simultaneously. Conversely, protected areas enhance biodi- versity and fish stocks (15). It is at regional and local scales that human actions and bio- diversity collide. On land, 25 areas, called hotspots, contain concentrations of endemic species that are disproportionately vulnera- ble to extinction after regional habitat de- struction (16). These areas retain <10% of their original habitat and have unusually high human population densities (17). Lo- cally, those who destroy biodiversity do so because they are displaced, marginalized, and perceive no alternative. Others do so for short-term profit (3).

Is Protecting Biodiversity Economically Possible? Although a global reserve network covering ~15% of each continent might cost ~$30 bil- lion annually (18), reserves in tropical wilderness areas and hotspots need only cost a fraction of this. Tropical wilderness forests, predominantly the relatively intact blocks of the Amazon, Congo, and New Guinea are remote and sparsely populated. Land values are low and sometimes equivalent to buying out logging leases. Recent conservation con- cessions suggest ~$10/ha for acquisition and management (3). Securing an additional ~2 million km2 and adequately managing the ~2 million km2 already protected for biodiversi- ty and indigenous peoples requires a one-

time investment of ~$4 billion. Land prices for the densely populated hotspots are much higher. Of the 1.2 million km2 of unprotect- ed land, some will remain intact without im- mediate intervention, some is already too fragmented, and perhaps one-third consti- tutes the highest priority. A study of the South Africa fynbos hotspot (3) suggests a one-time cost of ~$1 billion, and so by ex- trapolation, ~$25 billion for the protection and adequate management of all hotspots. Additional marine reserves would likely re- quire ~$2.5 billion (3).

These sums, although large, undercut arguments that saving biodiversity is unaf- fordable. They are of the same order of magnitude as the individual wealth of the world’s richest citizens—and 1/1000th the value of the ecosystem services that biodi- versity provides annually (19). This sug- gests a strategy of leveraging funding from governments and international agencies through private sector involvement.

Will Protecting Areas Work? The pressures to destroy ecosystems are of- ten external (20). For example, the World Bank and the International Monetary Fund have indirectly encouraged governments to deplete their natural resources to pay off debt (21). Even when available, some coun- tries may view foreign purchase of conser- vation concessions as imperialism in a 21st- century guise. Almost all the hotspots were European colonies; one is still French terri- tory (3). Some countries have unstable gov- ernment, and others are at war.

Some countries have welcomed pre-emp- tive purchasing of logging rights and other conservation actions, recognizing the advan- tages of protecting forests and receiving funds to do so. Unfortunately, cutting forests and otherwise depleting resources is too of- ten a way to personal aggrandizement among some government officials (22). How good is even a well-intentioned government’s guaran- tee of a forest’s security when its peoples need wood for cooking or land for farms? Will the government return the concession fees to those whose livelihoods are affected?

Protected areas may be respected in one country, ignored in another, even attract ex- ploitation in a third. Although more money generally yields more protection, richly en- dowed parks may be severely threatened (Ev- erglades National Park; USA) and significant accomplishments are possible in the most economically unlikely places (Odzala Na- tional Park; Democratic Republic of Congo).

Whereas overall assessments of what conservation actions work, what do not, and why they are long overdue, discus- sions of possible factors typically devolve into idiosyncratic case histories. Likely, there is no single answer to these multi-

S. L. Pimm is at the Center for Environmental Re- search and Conservation, MC 5556, Columbia Uni- versity, New York, NY 10027, USA. Other author ad- dresses are available on Science Online (3).

*To whom correspondence should be addressed. E- mail: [email protected]

S C I E N C E ’ S C O M P A S S P O L I C Y F O R U M

P O L I C Y F O R U M : E N V I R O N M E N T

Can We Defy Nature’s End? Stuart L. Pimm,* Márcio Ayres, Andrew Balmford, George Branch,

Katrina Brandon, Thomas Brooks, Rodrigo Bustamante, Robert Costanza,

Richard Cowling, Lisa M. Curran, Andrew Dobson, Stephen Farber,

Gustavo A. B. da Fonseca, Claude Gascon, Roger Kitching, Jeffrey McNeely,

Thomas Lovejoy, Russell A. Mittermeier, Norman Myers, Jonathan A. Patz,

Bradley Raffle, David Rapport, Peter Raven, Callum Roberts, Jon Paul Rodríguez,

Anthony B. Rylands, Compton Tucker, Carl Safina, Cristián Samper,

Melanie L. J. Stiassny, Jatna Supriatna, Diana H. Wall, David Wilcove

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scaled problems. One process, however, emerges as a unanimous choice: to train and empower conservation professionals in each biodiversity-rich country.

Should Conservation Research and Management Be Centralized or Distributed? At present, these capabilities are highly centralized in industrialized nations, while many key tropical areas have few conser- vation professionals. Our experiences point to the pressing need for more and better-trained people. Those at La Selva (Costa Rica), Comision Nacional Para el Conocimiento y Uso de la Biodiversidad (CONABIO), Mexico, the Humboldt Insti- tute (Colombia), the Centre for Ecological Sciences of the Indian Institute of Science (India), and the International Centre for Liv- ing Aquatic Resources (ICLARM), Philip- pines have been in place long enough to as- sist in training a new generation. Budgets for effective centers are a few million dol- lars per year. Roughly half a billion dollars would support 25 centers for a decade, enough for each hotspot and wilderness for- est without centers plus additional centers for marine and freshwater hotspots.

Should Efforts Concentrate on Protection or on Slowing Harm? Most of us agree that immediate protec- tion of ecosystems and training of in-coun- try professionals is vital. Nonetheless, some effort should be allocated to actions to lighten the burden on future generations of conservation professionals (3). Others argue in favor of actions that stem the pro- cesses that harm biodiversity and encour- age those that protect it, with priority giv- en to actions yielding near-term results.

Economic subsidies that degrade the environment are a common problem across terrestrial, freshwater, and marine ecosystems (23, 24). For instance, massive economic subsidies make unsustainable fishing practices possible (25, 26). Biodi- versity can be depleted if property rights give ownership to those whose “economic use” translates into short-term forest clear- cutting, transient crops or grazing, and longer-term land degradation.

The public is often unaware of the costs of environmentally damaging policies. An- nually, subsidies for such policies cost $2 trillion globally (24). We recommend a fo- cused analysis on those governmental poli- cies that artificially alter market dynamics and that have the most detrimental impact on biodiversity. The overarching message is that sound economic and ecological strate- gies may often involve the same, and not conflicting, strategies. Alliances of the fis- cally frugal and the environmentally con-

cerned are a still unexplored possibility. We recommend a major outreach to na-

tional and international institutions that make loans for actions that degrade biodi- versity. Many of them could benefit from improved ecological standards that factor biodiversity protection into their decision- making. Obligations of parties to existing le- gal instruments (such as the United Nations Convention on Biological Diversity) should also be used to promote adequate incentives.

Biodiversity-rich countries often lack le- gal mechanisms to encourage conservation. Tax savings, transferable development rights, and mitigation credits would at least allow private, public or indigenous landown- ers to secure economic benefits. Globally, the wilderness forests, if lost, would greatly exacerbate increasing atmospheric CO2. Their value as carbon sinks alone appears to be broadly similar to our estimates of what it would take to protect them (27). Capturing these values could save large areas through efforts designed to highlight their true value.

Do We Know Enough to Protect Biodiversity? Most debate centers on identifying priority areas for conservation. Surely all remain- ing habitats across the species-rich tropics must be priorities, ones that do not depend on our knowing the scientific names for 1 of 10, or the geographical distributions of 1 of 100 species, or not having resolved complex issues of reserve selection (28). However, even modest scientific advances greatly improve the efficiency of our ac- tions. Knowing which areas within hotspots are especially important could re- duce costs considerably.

Paradoxically, we are not limited by lack of knowledge, but by our failure to synthe- size and distribute what we know. Museums and herbaria are vast repositories of data on what species occurred where, while decades of remote-sensing imagery detail how fast the remains of species’ ranges are shrink- ing. Although a few of us question the utili- ty of these taxonomic repositories, the ma- jority emphasize the urgent need for more, globally distributed taxonomy (29).

In contrast, there was broad consensus for a greatly expanded research effort into the links between biodiversity, ecosystems, their services, and people (30). Infectious diseases are entering human populations as our numbers increase and as we encroach upon tropical forests and other pathogen reservoirs. Global climate change will have major impacts on human health through changes in food production, access to fresh water, exposure to vector- and water-borne disease, sea-level rise and coastal flooding, and extreme weather events (31).

In conclusion, we share mixed senses of

concern, urgency, and optimism. Concern, because humanity’s numbers (and consump- tion) are increasing. Across several human generations, a transition to sustainable use of natural resources is essential, and we must protect biodiversity in the interim. The urgency is driven by the pending loss of a major portion of biological diversity in the first half of this century if we do not act im- mediately. Our optimism stems from the re- alization that greatly increasing the areas where biodiversity is protected is a clear and achievable goal, one potentially attainable by using funds raised in the private sector and leveraged through governments.

References and Notes 1. S. L. Pimm et al., Science 269, 347 (1995). 2. See www.ldeo.columbia.edu/pimmlab. 3. Supplementary material is available on Science On-

line at www.sciencemag .org/cgi/content/full/ 293/5538/2207/DC1

4. National Research Council, Research Priorities in Tropical Biology (National Academy of Sciences, Washington, DC, 1980).

5. N. Myers, The Primary Source: Tropical Forests and Our Future (Norton, New York, 1992).

6. D. C. Nepstad et al., Nature 398, 505 (1999). 7. S. L. Pimm, The World According to Pimm: A Scientist

Audits the Earth (McGraw-Hill, New York, 2001). 8. A. Grainger, Int. Tree Crops J. 5, 31 (1988). 9. M. Dynesius, C. Nilsson, Science 266, 753 (1994).

10. B. A. Stein, L. S. Kutner, J. S. Adams, Eds., Precious Her- itage: the Status of Biodiversity in the United States (Oxford Univ. Press, Oxford, 2000).

11. M. Reisner, Cadillac Desert: The American West and Its Disappearing Water (Penguin USA, New York, 1993).

12. P. P. Micklin, Science 241, 1170 (1988). 13. United National Environment Programme (UNEP),

Status of Desertification and Implementation of the United Nations Plan of Action to Combat Desertifi- cation (UNEP, Nairobi, Kenya, 2000).

14. Food and Agriculture Organization of the United Na- tions, “The state of world fisheries and aquaculture in 2 0 0 0 ” ; ava i l a b l e a t w w w. fa o. o rg / d o c re p / 0 0 3 / x8002e/x8002e00.htm (2000).

15. C. M. Roberts, J. P. Hawkins, Trends Ecol. Evol. 14, 241 (1999).

16. N. Myers et al., Nature 403, 853 (2000). 17. R. P. Cincotta et al., Nature 404 990 (2000). 18. A. James, K. J. Gaston, A. Balmford, Nature 404, 120

(2000). 19. R. Costanza et al., Nature 387, 253 (1997). 20. C. Kremen et al. Science 288, 1828 (2000). 21. N. Sizer, D. Plouvier, Increased Investment and Trade

by Transnational Logging Companies in Africa, the Caribbean, and the Pacific (Joint Report for World Wide Fund for Nature-Belgium, World Resources In- stitute, and WWF-International, 2001).

22. See www.transparency.de/documents/newsletter/ 200.3/third.html

23. N. Myers, Nature 392, 327 (1998). 24. ———, J. Kent, Perverse Subsidies: How Tax Dollars

Can Undercut Both the Environment and the Econo- my. (Island Press, Washington, DC, 2001).

25. M. Milazzo, Subsidies in World Fisheries (World Bank, Washington, DC, 1998).

26. D. Ludwig et al., Science 260, 17 (1993). 27. J. J. Hardner, P. C. Frumhoff, D. C. Goetze, Mitigat.

Adapt. Strateg. Global Change 5, 61 (2000). 28. S. L. Pimm, J. H. Lawton, Science 279, 2068 (1998) 29. A. Sugden, E. Pennisi, Science 289, 2305 (2000) and E.

O. Wilson, Science 289, 2279 (2000). That issue prompted responses in Letters [A. T. Smith et al., Sci- ence 290, 2073 (2000)] and a response to those re- sponses [W. J. Kress, Science 291, 828 (2001)].

30. J. A. Patz, D. Engelberg J. Last, Annu. Rev. Publ. Health 21, 271 (2000).

31. D. J. Rapport, R. Costanza, A. J. McMichael, Trends Ecol. Evol. 13, 397 (1998).

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