Carbon Dioxide and Climate

Pieter TansNOAA Earth System Research Laboratory

Boulder, Colorado

National Science Teachers AssociationNational Conference

New Orleans, 19 March 2009

You can use slides from my presentation if you acknowledge the author

Carbon Dioxide

CO2

O=C=O

Carbonic Acid

CO2

H2O

O2

Photosynthesis

THE GREENHOUSE EFFECT

THE GREENHOUSE EFFECT

What is infrared radiation?

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water vapor (H2O) 0 - 4 % (average 0.4 %) from 1800: to today:carbon dioxide (CO2) 0.028 % 0.038 %

methane (CH4) 0.00008 % 0.00017 %

nitrous oxide (N2O) 0.000028 % 0.000032 %

THE GREENHOUSE EFFECT

THE GREENHOUSE GAS INCREASES ARE DUE TO US

THE GREENHOUSE GAS INCREASES ARE DUE TO US

Gton CCumulative fossil fuel emissions (Jan. 2008) 340 ± 25

(source: CDIAC) Observed atmospheric increase (Jan. 2008) 217 ± 8

(source: ESRL)

WE CAUSED IT: DECADAL MASS BALANCE OF CARBON

GtCCumulative fossil fuel emissions (Jan. 2008) 340 ± 25

(source: CDIAC) Observed atmospheric increase (Jan. 2008) 217 ± 8

(source: ESRL) Observed ocean increase through 1994 118 ± 19

(Sabine et al., Science 2004)

oceans, extrapolated through 2007 151

WE CAUSED IT: DECADAL MASS BALANCE OF CARBON

fossil fuel emissions + terrestrial sources = atmospheric increase + ocean increase

Conclusions:

The observed increase in atmospheric carbon dioxidesince pre-industrial times is entirely due to human activities. The measured increases in the atmosphereand oceans add up approximately to the cumulative fossil fuel emissions.

The relative contribution of NET changes in terrestrial biomass and organic matter has dwindled over timeand is now relatively small.

THE GREENHOUSE GAS INCREASES ARE DUE TO US

FURTHER EVIDENCE: ISOTOPIC RATIO SIGNATURES

Use isotopic ratios to distinguish different sources of carbon.

In the atmosphere we have 12CO2 13CO2 14CO2

13C/12Csample – 13C/12Creference 14C/Csample

13C/12Creference 14C/Creference

δ13C 13C/12C ratio δ14C (approximate) (approximate)

Atmosphere -8 ‰ 0.011147 1.06

From oceans -8 ‰ 0.011147 1.08

Terrestrial biosphere -26 ‰ 0.010945 1.10

Coal -24 ‰ 0.010967 0

Oil -28 ‰ 0.010923 0

Natural gas -45 ‰ 0.010732 0

FURTHER EVIDENCE: ISOTOPIC RATIO SIGNATURES

δ13C ≡

Sources: Friedli (1986), Francey (1999 ), and ESRL & INSTAAR

FURTHER EVIDENCE: ISOTOPIC RATIO SIGNATURES

FURTHER EVIDENCE: ISOTOPIC RATIO SIGNATURES

FURTHER EVIDENCE: NORTH-SOUTH GRADIENT

Source: NOAA/ESRL

Conclusions:

The evidence from 13C and 14C demonstrates that the atmospheric increase is caused by organic material,or something derived from organic material, and thatthe source is very old, 50,000 years or more.

Furthermore, the source is concentrated in the northernhemisphere, and has increased roughly in proportion to the global rate of consumption of fossil fuels.

THE GREENHOUSE GAS INCREASES ARE DUE TO US

WE CANNOT AFFORD TO WAIT

Potential feedback effect: permafrostsoils in the Arctic store 500-900 Gton Cthat could be converted to CH4 and CO2 as the Arctic warms.

WE CANNOT AFFORD TO WAIT

WE CANNOT AFFORD TO WAIT

When the earth’s radiation balance is disturbed, the climate will be forced to change. “Climate sensitivity” is defined as the temperature change produced by a given amount of radiation change, like absorption by greenhouse gases.

Why is climate sensitivity so unpredictable?

Climate sensitivity (called “λ”) to greenhouse gas forcing alone, without any feedbacks, equals: λo = 1.2 K (2.2 deg F) per doubling of CO2

ΔF ΔT

FT o

λo

water vapor (f1)

snow & ice melt (f2)

CH4 & CO2 from permafrost melt (f3)

Ff

T o

1

WE CANNOT AFFORD TO WAIT

Alexander McDonald, adapted from Roe & Baker, Science 2007

WE CANNOT AFFORD TO WAIT

R. Feely et al., 2006

Ocean acidification and threat to coral reefs

WE KNOW HOW TO DECREASE OUR EMISSIONS

Source: CDIAC

WE KNOW HOW TO DECREASE OUR EMISSIONS

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Energy efficiency and conservation

Product labeling with estimates of embedded energy, carbon and water

Renewable energy sources

Electric cars? Fuel cell motors?

Carbon capture and sequestration

Biochar

Nuclear electric power

carbontracker.noaa.gov

Net ecosystem flux for North Americafor 2002: -0.17 Gton C

Net ecosystem flux for North Americafor 2005: -0.76 Gton C

carbontracker.noaa.gov

Data: NASA GISS

Glacier Bay, AK, in 1940 and in 2004

Record melting of Arctic sea ice in 2007

Mountain PineBeetle outbreaks

Photos: USGS

Photos: Forest Serviceof Canada

Picture: NASA

sea level rise

or 6 m ?1 m ?

Fossil fuel proved reserves and rate of use.

global United States reserves P R/P reserves P R/P

hard coal 311 2.62 119 83 0.40 208soft coal 135 0.47 287 47 0.19 247

oil 122 3.32 37 3.1 0.72* 4.3* natural gas 97 1.52 64 3.2 0.31* 10*

Proved reserves are the amount that can be recovered with existing availabletechnology under present and expected local economic conditions.

R = dQ/dt = k Q(1-Q/N)

N total resource

Q cumulative extractionR rate of extractionk initial rate of growth

Source: U.S. Energy Information Administration

Population(millions)

U.S.

China World

13001450

300365

6500

820020062030

Primary energy consumption per capita

Source of energy data: U.S. Energy Information Administration

20062030

U.S.

China

World

0.4% / yr

3.6 % / yr

1.3 % / yr

11,200 W12,300 W

1,340 W3,200 W

3,000 W2,300 W

Global energy demand is expected to grow 60% from 2006 to 2030.

If met by fossil fuels, atmospheric CO2 increase isexpected to accelerate from 2.0 to 3.2 ppm/yr