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Elevated CO 2 and the global C cycle

Elevated CO 2 and the global C cycle

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Elevated CO 2 and the global C cycle

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  1. Elevated CO2 and the global C cycle • I. Is atmospheric CO2 increasing? • - Historic, millenial, and ice age patterns • II. Is it caused by humans? • - 3 lines of evidence • III. Consequences • Direct • Indirect

  2. Rising atmospheric CO2 Schlesinger 1997

  3. Questions • 1. How does this fit into Earth’s long-term history? • 2. How do we know if recent changes are caused by human activities? • 3. What might be the consequences?

  4. 23.22

  5. 23.21

  6. http://www.realclimate.org/index.php/archives/2005/11/650000-years-of-greenhouse-gas-concentrations/http://www.realclimate.org/index.php/archives/2005/11/650000-years-of-greenhouse-gas-concentrations/ Here’s the more recent 650,000 year record from the EPICA ice core in Antarctica. The black line is the temperature proxy.

  7. Questions • 1. How does this fit into Earth’s long-term history? • 2. How do we know if recent changes are caused by human activities? • a. Timing • b. C budgeting • c. C signatures – 14C • 3. What might be the consequences?

  8. Rising atmospheric CO2 Schlesinger 1997

  9. Global carbon budgeting

  10. The Global Carbon Cycle - 1990sUnits Gt C and Gt C y-1 Atmosphere 3.2 …are leading to a build up of CO2 in the atmosphere. 750 63 6.3 Fossil Deposits About 16,000 1.6 60 Plants Fossil emissions ... 500 Soil 91.7 90 2000 …and land clearing in the tropics... The KP seeks to reduce net carbon emissions by about 0.3 Gt C below 1990 levels from industrial countries Oceans 39,000

  11. Questions • 1. How does this fit into Earth’s long-term history? • 2. How do we know if recent changes are caused by human activities? • 3. What might be the consequences?

  12. Consequences of Elevated CO2 • Direct effects – more on these later • On plant growth • On decomposition • 2. Indirect effects • Warming • Effects of warming • Sea level rise • Changes in precipitation • Storm frequency and intensity? • Biological changes: species range shifts, diseases?

  13. Enhanced greenhouse effect Starr&Taggart Fig. 37.12

  14. And other greenhouse gases…

  15. Elevated CO2 effects: increased temperature

  16. Global Warming effects –sea level rise

  17. Global Warming effects – extreme weather

  18. Remaining questions: • How much warming will occur? • How distributed? • Consequences? • What can be done? (Adaptation, mitigation)

  19. Greenhouse gas emission scenarios

  20. Global Warming effects – long-term

  21. The Global Carbon Cycle - 1990sUnits Gt C and Gt C y-1 Atmosphere 3.2 …are leading to a build up of CO2 in the atmosphere. 750 63 6.3 Fossil Deposits About 16,000 1.6 60 Plants Fossil emissions ... 500 Soil 91.7 90 2000 …and land clearing in the tropics... The KP seeks to reduce net carbon emissions by about 0.3 Gt C below 1990 levels from industrial countries Oceans 39,000

  22. Questions • What causes uptake by natural systems? • How much capacity to continue absorbing CO2? • What might limit their uptake capacity? • What can we do to enhance ecosystem uptake and thereby slow the atmospheric increase?

  23. The End

  24. Global Warming effects – change in precipitation