1. Alan F. Hamlet JISAO/CSES Climate Impacts Group Dept. of Civil and Environmental Engineering University of Washington Hydrologic Implications of Climate Change for the Western U.S., Pacific Northwest, and Washington State

2. Image Credit: National Snow and Ice Data Center, W. O. Field, B. F. Molnia http://nsidc.org/data/glacier_photo/special_high_res.html Aug, 13, 1941Aug, 31, 2004 Recession of the Muir Glacier

3. Global Climate Change Scenarios for the PNW

4. Consensus Forecasts of Temperature and Precipitation Changes from IPCC AR4 GCMs

5. Mote, P.W. and E. P. Salathe Jr., 2009: Future climate in the Pacific Northwest (in review) 21 st Century Climate Impacts for the Pacific Northwest Region

6. Effects of the PDO and ENSO on Columbia River Summer Streamflows Cool Warm PDO Red=warm ENSO Green=ENSO neutral Blue=cool ENSO

7. Snowpack

8. Snow Model Schematic of VIC Hydrologic Model and Energy Balance Snow Model

9. Mote P.W.,Hamlet A.F., Clark M.P., Lettenmaier D.P., 2005, Declining mountain snowpack in western North America, BAMS, 86 (1): 39-49 Trends in April 1 SWE 1950-1997

10. Trend %/yr DJF avg T (C) Trend %/yr Overall Trends in April 1 SWE from 1947-2003 Hamlet, A.F., Mote, P.W, Clark, M.P., Lettenmaier, D.P., 2005: Effects of temperature and precipitation variability on snowpack trends in the western U.S., J. of Climate, 18 (21): 4545-4561

11. Trend %/yr DJF avg T (C) Trend %/yr Temperature Related Trends in April 1 SWE from 1947-2003 Hamlet, A.F., Mote, P.W, Clark, M.P., Lettenmaier, D.P., 2005: Effects of temperature and precipitation variability on snowpack trends in the western U.S., J. of Climate, 18 (21): 4545-4561

12. Trend %/yr DJF avg T (C) Trend %/yr Precipitation Related Trends in April 1 SWE from 1947-2003 Hamlet, A.F., Mote, P.W, Clark, M.P., Lettenmaier, D.P., 2005: Effects of temperature and precipitation variability on snowpack trends in the western U.S., J. of Climate, 18 (21): 4545-4561

13. Plotting Areas of High Hydrologic Disturbance Elsner et al., 2009: Implications of 21st Century climate change for the hydrology of Washington State (in review)

14. Change in Long-Term Mean April 1 SWE in WA Elsner et al., 2009: Implications of 21st Century climate change for the hydrology of Washington State (in review) -29%-27% -44% -65% -37% -53%

15. Changes in Seasonal Streamflow Timing

16. Simulated Changes in Natural Runoff Timing in the Naches River Basin Associated with 2 C Warming Impacts: Increased winter flow Earlier and reduced peak flows Reduced summer flow volume Reduced late summer low flow

17. Projected Streamflow Timing Shifts in Washington

18. Historical and Projected 21 st Century Flows for the A1b Scenario Chehalis River

19. Historical and Projected 21 st Century Flows for the A1b Scenario Quinault River

20. Historical and Projected 21 st Century Flows for the A1b Scenario Elwah River

21. Historical and Projected 21 st Century Flows for the A1b Scenario Skagit River

22. Historical and Projected 21 st Century Flows for the A1b Scenario Yakima River

23. Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key aspects of freshwater salmon habitat in Washington State, (in review) Climate Change Will Result in Widespread Transformation of Snowmelt and Transient Watersheds to Rain Dominant Watersheds

24. Changes in Hydrologic Extremes

25. Tmin Tmax PNW CACRB GB Regionally Averaged Temperature Trends Over the Western U.S. 1916-2003

26. X 20 2003 / X 20 1915 DJF Avg Temp (C) Simulated Changes in the 20-year Flood Associated with 20 th Century Warming X 20 2003 / X 20 1915

27. Summary of Flooding Impacts Rain Dominant Basins: Possible increases in flooding due to increased precipitation intensity, but no significant change from warming alone. Mixed Rain and Snow Basins Along the Coast: Strong increases due to warming and increased precipitation intensity (both effects increase flood risk) Inland Snowmelt Dominant Basins: Relatively small overall changes because effects of warming (decreased risks) and increased precipitation intensity (increased risks) are in the opposite directions.

28. Floods in western WA are expected to increase in magnitude due to the combined effects of warming and increasingly intense winter storms. In other parts of the State, changes in flooding are smaller, and in eastern WA projected reductions in flood risk are common due to loss of spring snow cover. Future Projections of Flood Risk in Washington Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key aspects of freshwater salmon habitat in Washington State, (in review)

29. 7Q10 values are projected to systematically decline in western WA due to loss of snowpack and projected dryer summers Changes in Low Flow Risks Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key aspects of freshwater salmon habitat in Washington State, (in review)

30. Landscape Scale Disturbance

31. 1910 1930 1950 1970 1990 2010 0 0 1.0 2.0 3.0 4.0 5.0 6.0 Year 8.0 7.0 1999 2001 2000 2003 2002 Annual area (ha × 10 6 ) affected by MPB in BC 2005 9.0 2004 Bark Beetle Outbreak in British Columbia (Figure courtesy Allen Carroll)

32. The recession of the Illecillewaet Glacier at Rogers Pass between 1902 and 2002. Photographs courtesy of the Whyte Museum of the Canadian Rockies & Dr. Henry Vaux. 1902 2002 Wide-Spread Glacial Retreat has Accompanied 20 th Century Warming.

33. Loss of glacial mass may increase summer flow in the short term and decrease summer flow in the long term.

34. Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key aspects of freshwater salmon habitat in Washington State, (in review) Warming Air Temperatures will Increase Water Temperature

35. Adaptation

36. Anticipate changes. Accept that the future climate will be substantially different than the past. Use scenario based planning to evaluate options rather than the historic record. Expect surprises and plan for flexibility and robustness in the face of uncertain changes rather than counting on one approach. Plan for the long haul. Where possible, make adaptive responses and agreements “self tending” to avoid repetitive costs of intervention as impacts increase over time. Approaches to Adaptation and Planning