Carbon footprint

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Biol108_Carbon_Cycle.pdf

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6/19/18

Ecosystems: Biogeochemical Cycles

The Disruption of the Carbon Cycle

Nutrients cycle through ecosystems

Nutrients cycle through ecosystems.� �

Nutrients flow from sink to sink.

Nutrients cycle through ecosystems.� �

Nutrients flow from sink to sink.� �

Biogeochemical � �

Nutrient flows are generated by organisms and geological processes.�

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The Carbon Cycle

The alteration of a biogeochemical cycle

Three patterns    1) Increase in airborne carbon as CO2    2) Increase in global temperature    3) Ocean acidification    Mechanism - What is the link?

The Carbon Cycle    

Terrestrial Components  + 

Ocean Components  + 

Geological Sinks

The Carbon Cycle    

Terrestrial Components

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Carbon Cycle - Biological Carbon Cycle - Biological

Carbon cycle •  Atmosphere contains large sink of C as

CO2

Carbon Cycle - Biological

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Carbon cycle •  Atmosphere contains sink of C as CO2 •  Plants absorb CO2 via photosynthesis and

convert it to carbohydrates

Carbon Cycle - Biological

Carbon cycle •  Atmosphere contains sink of C as CO2 •  Plants absorb CO2 via photosynthesis and

convert it to carbohydrates •  Animals metabolize carbohydrates and

release C as CO2

Important terrestrial carbon sinks include

Forests

Peatlands Permafrost

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Forests

Peatlands

Permafrost

The Carbon Cycle   

Terrestrial Components  + 

Ocean Components

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Carbon cycle •  Atmosphere contains sink of C as CO2 •  Plants absorb CO2 via photosynthesis and

convert it to carbohydrates •  Animals metabolize carbohydrates and

release C as CO2 •  Sea surface absorbs and releases CO2 into

atmospheric sink.

Carbon cycle •  Atmosphere contain large sink of C as CO2 •  Plants absorb CO2 and via photosynthesis convert

it to carbohydrates •  Animals metabolize carbohydrates and release C

as CO2 •  Sea surface absorbs and releases CO2 into

atmospheric sink. •  Marine organisms use C to build their bodies. In

addition C cycles through oceans in several forms.

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The Carbon Cycle   

Terrestrial Components  + 

Ocean Components  + 

Geological Sinks

Geological sinks   

Over long periods of time   

1) Biological carbon is converted to coal, oil, and gas 

  2) Marine organisms die and become ocean sediments and eventually turn

into rocks (limestone, etc).

Carbon cycle •  Atmosphere contain large sink of C as CO2 •  Plants absorb CO2 and via photosynthesis convert it to

carbohydrates •  Animals metabolize carbohydrates and release C as CO2 •  Sea surface absorbs and releases CO2 into atmospheric

sink. •  Marine organisms use C to build their bodies. In addition C

cycles through oceans in several forms. •  Carbon is sequestered as fossil fuels and in ocean

sediments.

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Carbon cycle •  Atmosphere contain large sink of C as CO2 •  Plants absorb CO2 and via photosynthesis convert it to

carbohydrates •  Animals metabolize carbohydrates and release C as CO2 •  Sea surface absorbs and releases CO2 into atmospheric

sink. •  Marine organisms use C to build their bodies. In addition C

cycles through oceans in several forms. •  Carbon is sequestered as fossil fuels and in ocean

sediments. •  Humans release stored C by burning fossil fuels and cutting

down forests.

Carbon Cycle - Key Points •  Carbon cycles through several compartments

– Atmosphere – Oceans – Biological – Geological

•  Some carbon is sequestered into sinks •  Humans are releasing carbon from geological

sink faster then it is returned and can be absorbed by oceans.

Which of the following are human generated sources of carbon that could increase atmospheric levels of CO2? 1. Driving a gasoline powered car. 2. Riding a bicycle. 3. Exhaling during breathing. 4. All of the above. 5. None of the above.

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Carbon Cycle - Biological

How have atmospheric CO2 concentrations changed over time?

Ice-core Data

Atmospheric Gases

Isotopic Ratios - Temperature

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37 38

800,000 year CO2 trend

Mauna Loa

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Why is there a yearly cycle � in CO2 levels?

Why is there a yearly cycle in CO2 levels?

•  Fall/Winter CO2 released via decomposition.

•  Spring/Summer CO2 absorbed via photosynthesis.

•  Greater land area in northern versus southern hemisphere.

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800,000 year CO2 trend

400 ppm

400

Since 1880

280 ppm to 405 ppm

125 ppm change

During ice ages 100 ppm change took 10,000’s of years

Volcanoes and CO2

Calbuco volcano in Chile

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Volcanoes and CO2 •  When volcanoes release magma this

also release CO2 and other gases (SO2, etc.)

•  The best estimate is that volcanoes produce about 200 million tons of CO2 annually.

•  Humans produce about 26.8 billion tons of CO2 annually.

•  Volcanoes produce less than 1% of what humans do. 49

How do we know the CO2 is from human activity?

  1) Correlation between CO2

increase and increase in use of fossils fuels. 

But correlation is   not causation!

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  How do we know the CO2 is from

human activity?   

1) Correlation between CO2 increase and increase in use of

fossils fuels.   

2) Isotope signature of atmospheric CO2.

Isotopes

Same element, different number of neutrons.

Hydrogen Deuterium Tritium

Isotopic signature of CO2   from fossil fuels

•  Common isotopes of carbon are 12C and 13C. • Plants have a preference for the lighter isotopes (12C vs. 13C); thus they have lower 13C/12C ratios. •  Since fossil fuels are ultimately derived from ancient plants, plants and fossil fuels all have roughly the same 13C/12C ratio – about 2% lower than that of the atmosphere. •  As CO2 from these materials is released into, and mixes with, the atmosphere, the average 13C/12C ratio of the atmosphere decreases.

Why is the amount of   CO2 increasing?

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Carbon balance

carbon released into atmosphere minus (carbon absorbed by land, ocean sinks, and geological sinks) = carbon left as C in the atmosphere

Carbon emitted

P = 1,000,000,000,000,000

Carbon released into atmosphere

Carbon emitted

Carbon absorbed land

Carbon absorbed ocean

P = 1,000,000,000,000,000

Minus carbon absorbed by land and ocean sinks

Carbon emitted

Carbon Atmosphere

P = 1,000,000,000,000,000

Equals what’s left as C in the atmosphere

Carbon absorbed land

Carbon absorbed ocean

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Currently where does the CO2 that humans emit end up?

Fate of Anthropogenic CO2 Emissions (2000-2008)

Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS, updated

1.4 PgC y-1

+ 7.7 PgC y-1 3.0 PgC y-1

29%

4.1 PgC y-1

45%

26% 2.3 PgC y-1

Fate of Anthropogenic CO2 Emissions (2000-2008)

Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS, updated

1.4 PgC y-1

+ 7.7 PgC y-1 3.0 PgC y-1

29%

4.1 PgC y-1

45%

26% 2.3 PgC y-1

55% absorbed by natural systems

Fate of Anthropogenic CO2 Emissions (2000-2008)

Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS, updated

1.4 PgC y-1

+ 7.7 PgC y-1 3.0 PgC y-1

29%

4.1 PgC y-1

45%

26% 2.3 PgC y-1

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How long does CO2 stay   in the atmosphere?

What are the predictions for future emissions?

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Sources of uncertainty with large potential consequences

Feedbacks and Tipping Points   

Arctic carbon sinks   

Arctic methane sinks