PNW Climate Change Impacts & Related Studies Marketa McGuire Elsner Climate Impacts Group Center for Science in the Earth System Joint Institute for the Study of the Atmosphere and Ocean University of Washington November 28, 2007 Public Meeting of the League of Women Voters Climate science in the public interest

Why Climate Change Matters  The PNW’s ecosystems, communities, and economy are sensitive to changes in climate.  Global and regional climate is already changing, and these changes are expected to accelerate in the coming decades.  Significant climate change impacts are projected, and the impacts expected in the next few decades are largely unavoidable.  Local governments are on the front line with respect to dealing with climate impacts.

Observations Models using natural forcings only Models using natural and anthropogenic forcings

21 st Century Warming in the PNW

Precipitation Projections - 21 st Century

824 snow courses 73% – trends Large – trends PNW Some + trends SW Trend in Apr 1 Snowpack

Spring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basins Snowpack will melt earlier with warmer spring temperatures Lower Spring Snowpack +4°F, +4.5% winter precip April 1 Snowpack

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

Warmer temperatures:  More water, less snow in winter mid-, low elevations  Less water in summer Increased risk of winter flooding in many basins (changes in urban flooding less clear) Increased risk of summer drought Negative impacts on hydropower production, irrigation water supply, instream flow protection More stress on urban water supplies Impacts on Water Resources Overall: climate change will require increasingly complex trade- offs between competing management objectives

Washington State Climate Impacts Assessment Funding Source: Clean Air/Clean Fuels House Bill 1303 Answers to FAQ regarding HB 1303 from the Washington State Legislature website:

Human Health Agriculture SalmonForest Resources Coast LinesEnergy Infrastructure Water Resources A comprehensive state climate change assessment that includes the impacts of global warming Adaptation / Legal Barriers

Hydrologic Scenarios Database for the Columbia River Basin Working in Coordination With Regional Stakeholders Planning Framework Incorporating Climate Information and Uncertainty  Ecology  BPA  NPCC  State of OR  British Columbia (BC Hydro, Ministry of Environment)  ~20 GCMs  2 Emissions Scenarios  2 Downscaling Approaches  Large Scale Planning Studies  WRIA Water Supply Planning  Specific Planning Studies

Motivation for writing grew out of October 2005 King County climate change conference Written by the CIG and King County, WA in association with ICLEI – Local Governments for Sustainability Written to compliment ICLEI’s “Climate Resilient Communities” Program Focused on the process (not a sector), and written for a national audience

Why Climate Change Matters  Global and regional climate is already changing  These changes are expected to accelerate in the coming decades  Changes in snowpack and streamflow caused by rising temperatures will have important consequences for resources across the Pacific Northwest  Climate Impacts Group strives to provide information and tools to help planning and adaptation

Climate science in the public interest More information on PNW climate impacts and planning for climate change is available from The Climate Impacts Group Marketa McGuire Elsner

Projected range of global- scale warming by the 2090s: 3.2°F-7.2°F Warming expected through 21st century even if CO2 emissions end today due to persistence of greenhouse gases. Carbon Dioxide~60% of warming from GHG5 to 200 years Methane~20% of warming from GHG8 to 12 years Nitrous Oxide~6% of warming from GHG~120 years CF4 (Perfluoromethane)>50,000 years Estimated atmospheric lifetime of major greenhouse gas (per molecule) Data source: IPCC st Century Global Warming

Regional Impacts Salmon: increased stress from floods, warm streams, low summer streamflows Forests: increased risk of wildfire, vulnerability to insects, decreased growth & regeneration Coasts: inundation, erosion, habitat loss, flooding Agriculture: increased production?, decreased irrigation supply, increased heat stress/insects Recreation/Tourism: shortened winter ski season (improved access?), summer impacts from forest fires Hydropower: increased winter production, lower summer production Impacts on Other PNW Resources Overall: climate change will require increasingly complex trade-offs between competing management objectives

On-Line Survey Website Project Scope