1. Science of global climate change and potential impacts Alan F. Hamlet Philip Mote University of Washington Climate Science in the Public Interest

3. Carbon dioxide: up 32%

4. U.S. 186.1 Total CO 2 emission s since 1950 in billions of tons European Union 127.8 Russia 68.4 Ukraine 21.7 Poland 14.4 China 57.6 Japan 31.2 Australia 7.6 India 15.5 Kazakhstan 10.1 South Africa 8.5 Canada 14.9 Mexico 7.8 Trinidad and Tobago United Arab Emirate s Kuwait

5. Global Surface Temperature Variations

6. The earth is warming -- abruptly

8. Groisman et al., 2004

9. 1928 2000 The South Cascade glacier retreated dramatically in the 20th century Courtesy of the USGS glacier group

10. Most glaciers receding (except where precipitation has increased sharply)

11. March 5 Larsen B Ice shelf Antarctica

12. 20th century decline in NH snow cover R.D. Brown, J. Climate, 2000

13. Source: Mote et al. (2004) Trends in April 1 SWE 1950-1997

14. Human Causes or Natural Causes?

15. Natural Climate InfluenceHuman Climate Influence All Climate Influences

16. Human signal seen in climate change over North America, Asia and Europe (HC) 19002000 1900 2000Year

17. Future Projections

18. 21 st century temperature change IPCC (www.ipcc.ch)

19. Sea level rise IPCC (www.ipcc.ch)

20. Impacts

21. 1) Examples of “Minor to Moderate” Impacts Temperature-related discomfort (hot, humid summers) Increases in asthma or allergy symptoms Increased energy costs for air conditioning Loss of recreation opportunities (skiing, camping, fishing, boating on reservoirs) Increases in minor damages due to flooding or storm water drainage problems (e.g. flooded basements) Loss of snowpack, decreased water supplies, increased costs for water Coastal erosion, landslides, and increased insurance costs

22. 2) Examples of “Serious” Impacts Large-scale precipitation changes resulting in droughts and floods (high $$ in developed world, high human costs in developing world) Large-scale forest disturbance (fire, disease, insects) Sea level rise and increasing storm surge risks (particularly in island states and the developing world) Spread of temperature-controlled diseases (e.g. malaria) Significant reductions in global fresh water supplies and/or increasing water quality problems Large scale ecosystem damage, loss of species diversity

23. 3) Examples of Possible “Catastrophic” Impacts Rapid collapse of ocean circulation, or other irreversible, large-scale changes in climate. Permanent loss of soil or large-scale climate-related losses in arable land resulting in global famine. Catastrophic human health issues (e.g. world-wide plagues) Collapse of ocean ecosystems due to PH problems affecting primary productivity Global scale wars, genocide

24. Extras on PNW Snowpack and Water Supply

25. April 1 SWE (mm) Current Climate“2020s” (+1.7 C)“2040s” (+ 2.5 C) -44%-58% Changes in Simulated April 1 Snowpack for the Cascade Range in Washington and Oregon

26. Effects to the Cedar River (Seattle Water Supply) for “Middle-of-the-Road” Scenarios +1.7 C +2.5 C

27. Obs. Summer Water Availability is Declining 55 years Figures courtesy of Matt Wiley and Richard Palmer at CEE, UW

28. Effects of Temperature And Precipitation Effects of Temperature Alone Trends in April 1 SWE for the WA and OR Cascades -35% -23% -4.25% per decade -6.48% per decade

29. Transient SWE simulation from HadCM3 (A2) GCM run (with running 10 year average smoothing) Simulated from observed climate shows a declining trend of ~3KAF per decade (1935- 2000) HadCM3 simulated declines ~4KAF per decade Figure courtesy of Matt Wiley and Richard Palmer at CEE, UW

30. Length of ski season at Snoqualmie