Alan F. Hamlet JISAO/CSES Climate Impacts Group Dept. of Civil and Environmental Engineering

1. Effects of Projected Climate Change on the Hydrology of the Puget Sound Region and Potential Impacts to Puget Sound • Alan F. Hamlet • JISAO/CSES Climate Impacts Group • Dept. of Civil and Environmental Engineering • University of Washington

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

3. 1) Modeling experiments reproduce history of global temperatures remarkably well. 2) Natural forcings (e.g. volcanic eruptions and variations in solar radiation) alone cannot explain the rapid rise in temperature at the end of the 20th century.

4. Global Climate Change Scenarios for the PNW

5. 21st Century Climate Impacts for the Pacific Northwest Region Mote, P.W. and E. P. Salathe Jr., 2010: Future climate in the Pacific Northwest, Climatic Change, DOI: 10.1007/s10584-010-9848-z

6. Seasonal Precipitation Changes for the Pacific Northwest http://cses.washington.edu/db/pdf/wacciach1scenarios642.pdf

7. Projected sea level rise in Puget Sound relative to 1980-99 ? http://cses.washington.edu/db/pdf/moteetalslr579.pdf

8. Hydrologic Projections

9. Draft Hydrologic Products http://www.hydro.washington.edu/2860/

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

11. Watershed Classifications: Transformation From Snow to Rain Map: Rob Norheim

12. Effects to Rain Dominant Basins: Chehalis River near Grand Mound

14. SWE Runoff

15. Mixed Rain and Snow (Warm): Nisqually River at La Grande Dam

17. SWE Runoff

18. Mixed Rain and Snow (Colder): Snohomish River Near Monroe

21. Mild Snowmelt-Dominant Basins: Skagit at Mount Vernon

23. SWE Runoff

24. HumanHealth Infrastructure Water Resources Agriculture/Economics A comprehensive climate change impacts assessment for Washington State Coasts Energy Forest Resources Salmon Adaptation

25. Washington State Climate Change Impacts Assessment Executive Summary: http://cses.washington.edu/db/pdf/wacciaexecsummary638.pdf

26. Changes in Hydrologic Extremes

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. 2040s Changes in Flood RiskSkagit River at Mount Vernon B1 A1B 10 Member Ensemble Using the Hybrid Delta Downscaling Approach Historical

29. Recession of Whitechuck Glacier (Sauk Headwaters) 1973 2006 Photos courtesy of Dr. Mauri Pelto, Nichols College

30. Mass Balance of the Nisqually Glacier http://faculty.washington.edu/scporter/Rainierglaciers.html

31. Loss of glacial mass may maintain or even increase summer flow in the short term but is expected to decrease summer flow in the long term.

32. 9.0 2005 8.0 7.0 2004 6.0 5.0 Annual area (ha × 106) affected by MPB in BC 2003 4.0 3.0 2.0 2002 1.0 2001 2000 1999 0 1910 1930 1950 1970 1990 2010 Year Bark Beetle Outbreak in British Columbia (Figure courtesy Allen Carroll)

33. Sediment Transport

34. Sediment Impact Pathways: Increasing precipitation intensity may increase the severity of extreme events (e.g. mud slides, inundation of public access areas, etc.) Loss of glaciers may mobilize large “reservoirs” of sediment stored beneath them. Loss of snowpack may reduce the “armoring” effect of the snowpack in moderate elevation areas, leading to increased land slide risk and increased sediment loadings. (conversion of moderate elevation areas from avalanche risk to land slide risk). Changes in forest disturbance patterns, particularly fire, may be important driver of impacts.

35. Sediment Impacts in the Nisqually Headwaters http://www.abbegeomorphology.com/?p=69

36. Effects to Stream Temperature Mantua, N., I. Tohver, A.F. Hamlet, 2010: Climate change impacts on streamflow extremes and summertime stream temperature and their possible consequences for freshwater salmon habitat in Washington State, Climatic Change, online first, doi: 10.1007/s10584-010-9845-2

37. Changes in Low Flows 7Q10 values are projected to systematically decline in western WA due to loss of snowpack and projected dryer summers Mantua, N., I. Tohver, A.F. Hamlet, 2010: Climate change impacts on streamflow extremes and summertime stream temperature and their possible consequences for freshwater salmon habitat in Washington State, Climatic Change, doi: 10.1007/s10584-010-9845-2

38. Sea Level Rise Nicholls, R. J. and Cazenave, A. (2010) Sea-Level Rise and Its Impact on Coastal Zones. Science 328, 1517-1520

39. Approaches to Adaptation and Planning • Anticipate changes. Accept that the future climate will be substantially different than the past. • Use scenario based planning over long time scales to evaluate options rather than the historical 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.