1. Elevated CO 2 and the global C cycle I. Is atmospheric CO 2 increasing? - Historic, millenial, and ice age patterns II. Is it caused by humans? - 3 lines of evidence III. Consequences A.Direct B.Indirect

2. Rising atmospheric CO 2 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. Here’s the more recent 650,000 year record from the EPICA ice core in Antarctica. The black line is the temperature proxy. http://www.realclimate.org/index.php/archives/2005/11/650000-years-of-greenhouse-gas-concentrations/

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 – 14 C 3. What might be the consequences?

8. Rising atmospheric CO 2 Schlesinger 1997

11. Global carbon budgeting

12. The Global Carbon Cycle - 1990s Units Gt C and Gt C y -1 The KP seeks to reduce net carbon emissions by about 0.3 Gt C below 1990 levels from industrial countries Atmosphere Fossil Deposits 6.3 63 91.7 60 90 3.2 Plants Soil Oceans 750 500 2000 39,000 About 16,000 1.6 …are leading to a build up of CO 2 in the atmosphere. Fossil emissions... …and land clearing in the tropics...

14. 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?

15. Consequences of Elevated CO 2 1.Direct effects – more on these later a.On plant growth b.On decomposition 2. Indirect effects a.Warming b.Effects of warming i.Sea level rise ii.Changes in precipitation iii.Storm frequency and intensity? iv.Biological changes: species range shifts, diseases?

16. Enhanced greenhouse effect Starr&Taggart Fig. 37.12

17. And other greenhouse gases…

20. Elevated CO 2 effects: increased temperature

21. Global Warming effects –sea level rise

22. Global Warming effects – extreme weather

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

24. Greenhouse gas emission scenarios

25. Global Warming effects – long-term

26. The Global Carbon Cycle - 1990s Units Gt C and Gt C y -1 The KP seeks to reduce net carbon emissions by about 0.3 Gt C below 1990 levels from industrial countries Atmosphere Fossil Deposits 6.3 63 91.7 60 90 3.2 Plants Soil Oceans 750 500 2000 39,000 About 16,000 1.6 …are leading to a build up of CO 2 in the atmosphere. Fossil emissions... …and land clearing in the tropics...

27. Questions What causes uptake by natural systems? How much capacity to continue absorbing CO 2 ? What might limit their uptake capacity? What can we do to enhance ecosystem uptake and thereby slow the atmospheric increase?

28. The End

30. Global Warming effects – change in precipitation