Puget Sound Region’s Future Under Climate Change

The Climate Impacts Group at the University of Washington has issued a report on the future impact of climate change on the Puget Sound Region.

Ten UW authors contributed to the report, which draws on published papers, agency studies and regional adaptation efforts now taking place. This first major update since 2005 includes new topics such as sediment transport and landslides, more details on salmon impacts, ocean acidification and flooding, and more specifics about how different parts of the region will change.

Co-authors are Joe Casola, Ronda Strauch, Beth Curry,Brittany Jones, Harriet Morgan, Tania Busch Isaksen, Robert Norheim, Lara Whitely Binder, Meade Krosby and Amy Snover, all at the UW.

Projected changes include:

• Average air temperatures in Puget Sound will rise by between 2.9 and 5.4 degrees Fahrenheit by the 2050s, for the most optimistic scenario of future greenhouse gas emissions
• Ocean levels will rise by 4 to 56 inches by 2100, with the latest predictions offering more specifics on geographic variability and the effects of storm surges
• Winter flooding will increase due to rising oceans, more winter precipitation falling as rain rather than snow, and more frequent and intense heavy rains
• Landslide prediction requires more research, but more rain in the winter and more extreme heavy rain events are expected to increase the overall risk of landslides
• Rivers are projected to carry more sediment downstream, as glaciers recede and expose loose material, and higher river flows and more intense rainfall will likely act to increase erosion. For example, sediment in the Skagit River is projected to more than double by the end of this century.
• Peak river flows are projected to rise the most in places such as the Snohomish River that have a lot of area around the snowline, where warming will cause precipitation to shift from snow to rain
• Warmer air, less meltwater and lower summer flows will combine to raise river temperatures in the summer, making many waterways less hospitable for salmon
• Heat waves are expected to become more frequent. While smaller than the changes projected for Eastern Washington, recent UW research shows a bigger public-health risk west of the Cascades, where people are less prepared for the heat
• Agriculture west of the Cascades is very diverse, and the effects of climate change on this region are understudied
• Warmer oceans will likely favor more frequent toxic algae blooms
• Increasing acidity of seawater will affect the shellfish industry, and may increase the toxicity of some algal blooms. Impacts on other marine life are not yet fully known.

Here are the individual sections of the report in .pdf form:

• Executive Summary (with Front Matter & “How to Read this Report”)
• Section 1: Making Sense of Climate Change Projections
• Section 2: How Is Puget Sound’s Climate Changing?
• Section 3: How will Climate Change Affect the Water Cycle?
• Section 4: How will Climate Change Affect Sea Level?
• Section 5: How Will Climate Change Affect Landslides, Erosion, and Sediment Transport?
• Section 6: How is Circulation in Puget Sound Projected to Change?
• Section 7: How is Puget Sound’s Water Quality Changing?
• Section 8: How Will Climate Change Affect Agriculture?
• Section 9: How Will Climate Change Affect Terrestrial Ecosystems?
• Section 10: How Will Climate Change Affect Freshwater Ecosystems?
• Section 11: How Will Climate Change Affect Marine Ecosystems?
• Section 12: How Will Climate Change Affect the Built Environment?
• Section 13: How Will Climate Change Affect Human Health?
• Appendix A: Alternate Hydrologic Projections
• Appendix B: Maps of climate and hydrologic change: Basin average projections
• Appendix C: Maps of climate and hydrologic change: Full-resolution projections