Carbon Dioxide and Climate Pieter Tans NOAA Earth System Research Laboratory Boulder, Colorado National Science Teachers Association National Conference New Orleans, 19 March 2009 You can use slides from my presentation if you acknowledge the author

Carbon Dioxide CO 2 O=C=O Carbonic Acid CO 2 H2OH2O O2O2 Photosynthesis

THE GREENHOUSE EFFECT

What is infrared radiation? Nature, 2008

water vapor (H 2 O) % (average 0.4 %) from 1800: to today: carbon dioxide (CO 2 ) % % methane (CH 4 ) % % nitrous oxide (N 2 O) % % THE GREENHOUSE EFFECT

THE GREENHOUSE GAS INCREASES ARE DUE TO US

Gton C Cumulative 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

GtC Cumulative fossil fuel emissions (Jan. 2008)340 ± 25 (source: CDIAC) Observed atmospheric increase (Jan. 2008)217 ± 8 (source: ESRL) Observed ocean increase through ± 19 (Sabine et al., Science 2004) oceans, extrapolated through WE CAUSED IT: DECADAL MASS BALANCE OF CARBON fossil fuel emissions + terrestrial sources = atmospheric increase + ocean increase

Conclusions: The observed increase in atmospheric carbon dioxide since pre-industrial times is entirely due to human activities. The measured increases in the atmosphere and 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 time and 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 12 CO 2 13 CO 2 14 CO 2

13 C/ 12 C sample – 13 C/ 12 C reference 14 C/C sample 13 C/ 12 C reference 14 C/C reference δ 13 C 13 C/ 12 C ratio δ 14 C (approximate) (approximate) Atmosphere -8 ‰ From oceans -8 ‰ Terrestrial biosphere -26 ‰ Coal -24 ‰ Oil -28 ‰ Natural gas -45 ‰ FURTHER EVIDENCE: ISOTOPIC RATIO SIGNATURES δ 13 C ≡

Sources: Friedli (1986), Francey (1999 ), and ESRL & INSTAAR FURTHER EVIDENCE: ISOTOPIC RATIO SIGNATURES

FURTHER EVIDENCE: NORTH-SOUTH GRADIENT Source: NOAA/ESRL

Conclusions: The evidence from 13 C and 14 C demonstrates that the atmospheric increase is caused by organic material, or something derived from organic material, and that the source is very old, 50,000 years or more. Furthermore, the source is concentrated in the northern hemisphere, 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: permafrost soils in the Arctic store Gton C that could be converted to CH 4 and CO 2 as the Arctic warms. 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? πR 2 = σ T 4 4πR 2 Climate sensitivity (called “λ”) to greenhouse gas forcing alone, without any feedbacks, equals: λ o = 1.2 K (2.2 deg F) per doubling of CO 2 ΔFΔF ΔTΔT ΔF CO2 = 5.35 log (X CO2 /280) (Watt m -2 ) λoλo water vapor ( f 1 ) snow & ice melt ( f 2 ) CH4 & CO2 from permafrost melt ( f 3 )

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 Nature, 2008 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 America for 2002: Gton C Net ecosystem flux for North America for 2005: 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 Pine Beetle outbreaks Photos: USGS Photos: Forest Service of 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 soft coal oil * 4.3* natural gas * 10* Proved reserves are the amount that can be recovered with existing available technology under present and expected local economic conditions.

R = dQ/dt = k Q(1-Q/N) N total resource Q cumulative extraction R rate of extraction k initial rate of growth

Source: U.S. Energy Information Administration Population (millions) U.S. China World

Primary energy consumption per capita Source of energy data: U.S. Energy Information Administration U.S. China World 0.4% / yr 3.6 % / yr 1.3 % / yr 11,200 W 12,300 W 1,340 W 3,200 W 3,000 W 2,300 W Global energy demand is expected to grow 60% from 2006 to If met by fossil fuels, atmospheric CO2 increase is expected to accelerate from 2.0 to 3.2 ppm/yr