1. The realities of climate change The balance of evidence suggests that there is a discernible human influence on global climate. IPCC 2nd Assessment Report, 1996. There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activity. IPCC 3rd Assessment Report 2001 The balance of evidence suggests that there is a discernible human influence on global climate. IPCC 2nd Assessment Report, 1996. There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activity. IPCC 3rd Assessment Report 2001 S. Mulkey June 2006

2. Mechanism of atmospheric forcing

3. The greenhouse gases Relative importance Trends through 2002

4. The scientific consensus June 2005

5. Observed warming

6. Models predicted the effect of Pinatubo Global temperatures rose 1.1 o F over the 20 th Century. Models predict temperature to increase 2.5-10.5 o F between 1990 and 2100.

7. Greenhouse gases are higher now than in 650,000 years

8. Future shock

9. Consequences: temperatures will rise 1.5 - 6.0 o C Washington DC will change from having about 35 days above 90 o F to over 85 days per year by 2050. Temperature change by 2050

10. Consequences: redistribution of precipitation Green = increasing Brown = decreasing

11. Consequences: extreme weather 2004 - 1,717 tornados

12. Consequences: increased hurricane intensity Annual power dissipation (PDI) by tropical cyclones compared to September sea surface temperature (SST). Emanuel [Nature, 2005]

13. When North America was colonized by Western Europeans, Glacier National Park contained more than 120 glaciers. Presently there are 23 glaciers, and by 2050 there will be none. Consequences: decrease in terrestrial ice

14. Consequences: decreasing polar ice The Northwest Passage will become reality by 2050. Decreasing ice amplifies warming

15. Consequences: amplification from defrosting the permafrost Official climate projections do not include CO 2 and CH 4 emissions from melting permafrost. Because of this carbon release, warming will be faster than predicted. (Davidson & Janssens Nature 2006) IPCC 4th assessment preview: Expect a global 3.0 o C minimum increase by 2100. Recent papers put the average closer to 4.0 o C

16. Consequences: Sea level rise

17. Data adjusted for population growth

18. Consequences: infectious disease

19. Consequences: shifting agricultural productivity

20. Consequences: global species extinction On the basis of mid- range climate-warming scenarios for 2050, 15-37% of species will be “committed to extinction” - Thomas et al. Nature 2004.

21. Business as usual: the world in 2075 Sea level 0.25 meters (about 10 inches) higher Millions of human ecological refugees - sea level rise & disasters Agricultural productivity will shift up to 10 o North in N. America Up to 40% of existing biodiversity extinct Loss of most coral reefs - ocean warming & acidification Increased infectious disease - 800 million with malaria Over a third of the Amazon basin progressing to savanna Major ecosystems in transition from their present form 400 million people living with water shortage Increasing severe weather and intensity of tropical storms [The effects of global warming] “would emerge as if someone had subtly, but progressively, loaded a pair of dice.” - Kerry Emanuel 2005

22. Rapid climate change: tipping points & uncertainties How fast will Greenland melt? Will the Antarctic ice shelf come unplugged? When will the Atlantic conveyor belt slow down and stop? What is the ocean capacity to absorb heat and CO 2 ? What is the extent of amplification due to permafrost & sea ice melting?

23. “The greatest hoax ever perpetrated on the American people.” - Senator James Inhofe. 2005 “The global environmental effects of the industrial era will cast a long shadow on future generations everywhere, for all time.” David Orr. 2005. The Last Refuge.