A multi-model integrated assessment of the impacts of climate change in Washington State Marketa M. Elsner1, Lan Cuo2, A.F.Hamlet2, Dennis P. Lettenmaier1,2, Edward L. Miles1 JISAO/CSES Climate Impacts Group, Box 354235, University of Washington, Seattle, WA 98195 2. Department of Civil and Environmental Engineering, Box 352700, University of Washington, Seattle, WA 98195 AGU Annual Fall Meeting, San Francisco, CA. Dec 15-19, 2008 1. Abstract 3. Impacts on Washington Climate and Natural and Human Resources In April 2007, the State of Washington passed legislation mandating a comprehensive statewide assessment of the impacts of climate change over the next 100 years. The Climate Impacts Group (CIG) at the University of Washington Joint Institute for the Study of the Atmosphere and Ocean (JISAO) is working with Washington State University, Pacific Northwest National Laboratory, and state agencies to perform an integrated assessment on the effects of climate change for eight statewide sectors: public health, agriculture, the coastal zone, forest ecosystems, salmon, infrastructure, energy, and water supply and management. An additional Climate Scenarios Working Group serves the eight other sectors by providing projections of future regional climate, downscaled to 1/16th degree spatial resolution over the state of Washington. We utilize projections from A1B and B1 greenhouse gas emissions scenarios, as simulated by the full suite of 20 GCMs, archived in the 2007 Fourth Assessment Report of the IPCC. In this approach, we apply 40 ensembles of statistically downscaled future climate to drive hydrologic model simulations. Each sector incorporates the projections of climatic and hydrologic variables in their evaluations of the impacts of climate change. Here we present impacts on hydrologic variables (such as snowpack and streamflow), as well as related implications for several of the sectors listed above, over the State of Washington for three periods: the 2020s, 2040s and 2080s. We also discuss CIG’s collaboration with multi-stakeholder adaptation working groups to identify potential barriers to adaptation and strategies to address the projected impacts in each sector. Coasts Forests 21st Century Climate Projections 3” 6” 30” 50” 2050 2100 13” 40” 20” 10” Climate change will continue to cause significant changes in temperature & precipitation across Washington State. Based on simulations from 20 Global Climate Models (GCMs) and 2 emissions scenarios (A1B and B1), we find: Figure 3.7 Change is areas of potential poine species ranges Sea Level Rise (SLR) will shift the coastal beaches and increase erosion of unstable bluffs, endangering houses and other structures built near the shore or near the bluff edges. Shellfish may be negatively impacted by increasing ocean temperatures and acidity, due to shifts in disease and growth patterns, and to more frequent harmful algal blooms (HABs). These conclusions extend to the numerous ports and marinas in the Puget Sound region, which must accommodate to SLR or retreat to higher ground if they are to continue to function as major transshipping points for US-Asia trade. . Annual temperature will increase approximately 0.3°C, or roughly 0.5°F, per decade over the next 50 years. The greatest warming is predicted for summer months. The range of precipitation could increase or decrease but the projected mean change is small. There is considerable spread among models, but there is slightly greater likelihood of modest increases in winter and modest decreases in summer. The area burned by fire regionally is projected to increase 200-300% (scenario A1B). Mountain pine beetle poses a significant threat to Washington’s pine forests. Tree species composition will change as species respond uniquely to a changing climate. The area of severely water-limited forests will increase by 32% in the 2020s, and an additional 12% in both the 2040s and 2080s. Figure 3.4: Projected sea level rise in Washington’s waters relative to 1980-99, in inches. Shading roughly indicates likelihood. Infrastructure Stormwater impacts and management already carry significant economic costs for municipalities throughout western WA, as well as the rest of the state. The potential for changes in precipitation intensity would increase these costs. Agriculture 2. Background and Study Approach Figure 3.1: Projected change in seasonal and annual temperature (top) and precipitation (bottom) in the Pacific Northwest. B1 and A1B emissions scenarios represent the range of possible Greenhouse Gas projections for the 20 GCM ensembles. Yields of dryland winter wheat are projected to increase slightly from climate change alone for the 2020s, and 15-30% with elevated CO2 as the century progresses. Yields of irrigated potatoes are projected to decline 8% from climate change alone for the 2020s and 22% for the 2080s, but rising CO2 would cut these declines to only 2% and 3% respectively. In 2007, the State Legislature of Washington passed HB 1303 which mandated the preparation of a comprehensive assessment of the impacts of climate change on the State of Washington, with focus on the next 50 years. The Climate Impacts Group (CIG) at the University of Washington, in cooperation with two state agencies, is conducting an integrated assessment which focuses on the impacts of climate change in relation to public health, agriculture, the coastal zone, forest ecosystems, infrastructure, and water supply and management. Hydrology / Water Resources 2400mm 10mm April 1 SWE is projected to decrease by an average of approximately 28-29% across the state by the 2020s, 38-46% by the 2040s and 56-70% by the 2080s, based on the composite scenarios averaging the effects of all climate models By the 2080s, seasonal streamflow timing in snowmelt dominant and transient rain-snow mixed watersheds will shift significantly Annual runoff across the state is projected to increase by 0-2% by the 2020s, 2-3% by the 2040s, and 4-6% by the 2080s and these changes are mainly driven by projected increases in winter precipitation Figure 3.8 Comparison of 25 year 24 hour design storms based on observed and modeled data at SeaTac airport Human Health Washington State residents are currently more likely to die during heat events than during more temperate periods; risks increase during heat waves lasting 2 or more days, and are greatest for older adults. Climate change in Washington State is likely to lead to significantly more heat-related deaths throughout this century. Figure 2.1: Map of Pacific Northwest (Columbia River Basin plus coastal drainages) and Washington State. Figure 3.5: Generalized agricultural land use map for the State of Washington Apples and cherries are projected to be negatively affected by climate change for the 2020s scenario, with yield reductions of 3% and 20%, respectively even with the effects of higher CO2 Figure 3.2: Mean 1916-2006 (top right panels), projected 2020s, 2040s and 2080s simulated April 1 SWE in milimeters, using two emissions scenarios A1B (left) and B1 (right). 2.5cm is approximately equal to one inch. Figure 3.9 Mortality relative risks for all non-traumatic causes by heat event duration (99th percentile), Greater Seattle area, 1980-2006. Energy Salmon Although better control of air pollution has led to improvements in air quality, warmer temperatures threaten some of the sizeable gains that have been made in recent years. Additional Information More information on the Climate Impacts Group or WA State Climate Impacts Assessment: The Climate Impacts Group www.cses.washington.ed/cig Marketa McGuire Elsner mmcguire@u.washington.edu Figure 3.3. Effects on A) heating energy demand and B) cooling energy demand for several combined scenarios of population and climate averaged over WA state. Panel C) shows monthly averages of simulated system-wide energy production from the Columbia River hydro system for 20th century climate, compared to future scenarios for the 2020s, 2040s, and 2080s for the A1B emissions scenario. IPCC Fourth Assessment Report (AR4) daily climate projections for the 21st Century (at roughly 100-300 km spatial resolution) are downscaled using two different approaches: an empirical method and a regional climate model. The Pacific Northwest domain, bounded by latitudes 41.5° and 49.5°N and longitudes 111° and 124°W, is used for downscaling. Downscaled climate scenarios are input to one of two hydrologic models which calculate the water balance for the ensemble of projections. Sector groups utilize climate and hydrologic predictions to assess statewide impacts. We evaluate regional climate change impacts with focus on Washington State, which includes the lower Columbia River basin, as well as coastal drainages, including the Puget Sound basin Figure 3.6: August mean surface air temperature and maximum stream temperature for 1970-1999 (left) and the 2040s (right, emission scenario A1B) These results will be release in February 2009 in our final report. The Washington State Climate Change Impacts Assessment: Evaluating Washington’s Future in a Changing Climate Results will also be released at an all day conference on Febraury 12, 2009. Additional information may be found at: http://cses.washington.edu/cig/outreach/waccia/index.html In the 1980s, the majority of stations in the interior Columbia Basin are classificed as stressful (annual maximum weekly temperature >15.5°C. The duration of temperatures causing thermal migration barriers and extreme thermal stress are predict quadruple by the 2080s.