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5. Global Warming  The Evidence  Potential for change?  Can anthropogenic change be separated from natural change?  Can the world collectively decide to do something about global carbon dioxide emissions?

6. 6 What causes Global Warming? Addition of greenhouse gases to atmosphere Main culprit is CO 2

7. 7 7 CS Fig. 17.19

8. 8 8 CS Fig. 17.20

9. 99 CS Fig. 17.23

10. 10 CS Fig. 17.18

11. 11 Bubbles in glacial ice preserve air of past cent- uries: Tell us what CO 2 concentrations were like before the industrial revolution Edmonds, 1999

12. 12 Longer records

13. Global Temperatures projected to rise 3 to 9 °F Edmonds, 1999

14. Consequences? http://www.enviroweb.org/edf/in dex.html

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16. 16 CS Fig. 17.22

17. 17 Historical Data

18. 18 Change in surface temperatures, 1979-1998 Change in free atmosphere (<5 miles) temperatures, 1979-1998 Note: deep red is ~1 °F warmer, deep blue is ~1 °F cooler

19. The debate rages on! Newspaper articles show scientists do not all agree as to whether the planet is currently warming The vast majority of scientists, however, do agree that the planet is warming due to additions of greenhouse gases to the atmosphere 19

20. 20 Natural Climate Change 20

21. 21 Natural Climate Change Cooling of the last 100 million years, warming of the last 20,000 years well documented Short term change (10’s to 1000’s of years) less well documented Short term change less well understood  Role of oceans unclear  Role of tides (1800 year cycle) just coming into question

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23. 23 The Sulfate “Fingerprint”

24. 24 Best evidence that recent warming is anthropogenic From Mann and others, Nature, 1998 Three years in the 1990’s are the warmest in the Northern Hemisphere, by far, of the last 400 years!

25. 25 Where we stand: What we do know:  Atmospheric CO 2 concentrations have risen 50% since the beginning of the industrial revolution  With business as usual, CO 2 concentrations will continue to rise  CO 2 is a strong greenhouse gas What we’re pretty sure of:  Surface temps in the Northern Hemisphere are the highest they’ve been in 400 years  Climate models do a good job of predicting the impact of CO 2 rise What we’re not sure of:  Surface temps have risen more in the last 25 years than they would have without CO 2 increases

26. 26 Change in Minnesota “Recent research indicates a warming trend in Minnesota. A study of the climate record at Fort Snelling shows an increase of 2.9°F in average annual temperature between the 1860s and 1987, almost three times the worldwide average. Analyses of more than a hundred temperature-depth profiles in North America show that ground latitudes comparable to Minnesota’s indicated ground warming of up to 3.6°F.” From “Playing with Fire, Global Warming in Minnesota” 1999; data from Baker and Skaggs, 1989

27. 27 MN Biomes at risk

28. 28 Change in Lake Superior

29. 29 CS, page 390

30. 30 Bush Rejection of Kyoto Protocol May 2001 USAEuropeans angry Edmonds, 1999

31. 31 CS Fig. 17.23

32. 32 FCCC The ultimate objective of the Convention … is to achieve… stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.

33. 33 Developed and transitional countries Edmonds, 1999

34. 34 Kyoto Protocol: Annex 1 countries reduce emissions by average of 5.2% Edmonds, 1999

35. 35 The End Back