An integrated assessment of the impacts of climate change on Washington State Marketa McGuire Elsner University of Washington JISAO/CSES Climate Impacts Group Department of Civil and Environmental Engineering In cooperation with: Jeremy S. Littell, Edward L. Miles, Dennis P. Lettenmaier February 14, 2008 The Water Center’s 18th Annual Review of Research 2008 Climate science in the public interest

Washington State Climate Impacts Assessment Provides that, to reduce fossil fuel dependence and build our clean energy economy, the state should develop policies and incentives that help businesses, consumers, and farmers gain greater access to affordable clean fuels and vehicles and to produce clean fuels in the state. These policies and incentives should include: (1) Incentives for replacement of the most polluting diesel engines, especially in school buses; (2) Transitional incentives for development of the most promising in-state clean fuels and fuel feedstocks, including biodiesel crops and ethanol from plant waste; (3) Reduced fossil fuel consumption by state fleets; (4) Development of promising new technologies for displacing petroleum with electricity, such as "plug-in hybrids"; and (5) Impact analysis and emission accounting procedures that prepare Washington to respond and prosper as global warming impacts occur and as policies and markets to reduce global warming pollution are developed. Funding Source: Clean Air/Clean Fuels House Bill 1303 Answers to FAQ regarding HB 1303 from the Washington State Legislature website: http://apps.leg.wa.gov/billinfo/default.aspx

Human Health Infrastructure Agriculture Water Resources A comprehensive state climate change assessment that includes the impacts of global warming Coasts Energy Evaluate Impacts of Climate Change in 2020s, 2040s, 2080s Use IPCC 2007 Climate Scenarios Show regional impacts and areas of high and low sensitivity to climate change Characterize barriers to adaptation to these impacts (e.g., legal, institutional) and prioritize areas for future action Collaborate with Governor’s Climate Change Challenge Team To be completed December 2008 Forest Resources Salmon Adaptation / Legal Barriers

Goals of the Impacts Assessment Evaluate impacts of climate change into the next century use IPCC 2007 climate scenarios show regional impacts and areas of high and low sensitivity to climate change characterize barriers to adaptation to these impacts (e.g., legal, institutional) with help from UW Law School provide tools for policy makers and user groups collaborate with Governor’s Climate Change Challenge team To be completed December 2008

Evaluate current and proposed actions to reduce CO2 emissions Make recommendations on improved preparedness and adaptation Draft recommendations Complete Final report February 2008

Relationship between PAWGs and HB1303 Sectors

Data Needs to Support a 21st Century Planning Framework Incorporating Climate Information and Uncertainty Approach provides ensemble of variables that can be used to evaluate impacts of climate change 2 Emissions Scenarios 20 GCMs 2 Downscaling Approaches X X IPCC Climate Scenarios Precipitation Air Temperature Streamflow Soil Moisture PET VPD And more! Overall Process for HB1303 Project: Generally, a range of scenarios of climate change to 2100 are input to a hydrology model that provides projections of streamflow and other hydrologic variables. -We are utilizing 100 year projections from approximately 20 GCMs, each of which has projections using 2 emissions scenarios. These emissions scenarios, A1B and B1, represent stabilization of CO2 by 2100. The B1 scenario is more ecologically friendly than A1B. They generally represent the range of possibly temperature changes into the future. -The GCM scenarios, which are at a resolution of approximately 3-4 degrees, must be downscaled to the resolution of the hydrology model. We utilize 2 downscaling approaches including a statistical approach and an approach that incorporates results from regional climate models. The downscaled GCM predictions and resulting hydrologic predictions provide a range of possibilities of future climate change which the various sectors can use to evaluate the impacts in their areas. Hydrology Modeling

Projected Increases in PNW Temperature 14.4°F Changes relative to 1970-1999 7.2°F 3.6°F 0°F +2.2ºF (1.1-3.4ºF) +3.5ºF (1.6-5.2ºF) +5.9ºF (2.8-9.7ºF) °C 10.8°F The average warming rate in the Pacific Northwest during the next century is expected to be in the range 0.1-0.6°C (0.2-1.0°F) per decade, with a best estimate of 0.3°C (0.5°F) per decade. For comparison, observed warming in the second half of the 20th century was approximately 0.2°C (about 0.4°F) per decade. The warming trend for the 20th century overall was 0.15°F per decade. In every scenario, the future warming greatly exceeds natural variability. Trends in precipitation are less certain. A modest increase (+1-2%) in average annual precipitation is expected through the 2040s, although individual models produce a wide range of results.   Figure: Smoothed traces in temperature for the 39 model simulations, relative to the 1970-99 mean. The smooth curve for each scenario is the Reliability Ensemble Average (REA) value, calculated for each year. The average provided above each box is the REA for that decade; the low and high values represent the lowest and highest value from either scenario (B1 or A1B) 2020s temperature precipitation low 0.6°C (1.1°F) -9% average 1.2°C (2.2°F) +1% high 1.9°C (3.4°F) +12% 2040s temperature precipitation low 0.9°C (1.6°F) -11% average 2.0°C (3.5°F) +2% high 2.9°C (5.2°F) +12% 2080s temperature precipitation low 1.6°C (2.8°F) -10% average 3.3°C (5.9°F) +4% high 5.4°C (9.7°F) +20% 9

Hydrology and Water Resources Reduced snowpack and changes in soil moisture will occur. Declines in April 1 SWE vary between 35%-41% for the 2040s, depending on the emissions scenario. There are 40 total greenhouse gas emissions scenarios used to drive global climate models. The 40 scenarios are grouped into four families: A1, A2, B1, and B2. The CIG is using the B1 and A1B scenarios for the HB 1303 work. The B1 emissions scenario represents a slower increase in greenhouse gas emissions with stabilization of CO2 concentrations by 2100 (the concentration of carbon dioxide will be 550ppm in 2100). The A1B emissions scenario has higher greenhouse gas emissions than the B1 scenario: the concentration of carbon dioxide will be 720ppm in 2100. The A1B and B1 scenarios have the same population projections (population peaking mid-century then declining). The main difference in the scenarios is energy use. The A1B scenario story line has a balance between fossil fuels and other energy sources, while the B1 story line assumes the use of more clean and resource-efficient technologies. 10

Coasts 3” 6” 30” 50” 2050 2100 13” 40” 20” 10” Rising sea levels will increase the risk of flooding, erosion, and habitat loss along much of Washington’s 2,500 miles of coastline. Medium estimates of SLR for 2100: +2” for the NW Olympic Peninsula +11” for the central/southern coast +13” for Puget Sound Higher estimates (up to 4 feet in Puget Sound) cannot be ruled out. Episodic flooding will likely pose a greater risk than permanent inundation of low-lying areas from increases in mean sea level. Lower amounts of local SLR will be apparent on the northwest Olympic Peninsula given rates of local tectonic uplift that currently exceed projected rates of global SLR. SLR estimates for the central and southern Washington coast are more uncertain. Available (but limited) data suggests that uplift is occurring in this region, but at rates lower than observed on the northwest Olympic Peninsula. The 6” and 13” marks on the figure are the SLR projections for the Puget Sound region and effectively also for the central and southern WA coast (the rates are nearly identical for the central and southern coast: +5 inches by 2050 and +11 inches by 2100) Assumptions of continued rapid ice melt from Greenland and Antarctica are a major factor in the potential for higher amounts of SLR. 11

Agriculture Irrigation supplies are likely to decline significantly as a result of changes in snowpack, resulting in more frequent and more stringent prorationing of water to junior water rights holders. For dryland agriculture, climate change will force agricultural practices to adapt to longer growing seasons, reduced summer precipitation, and increasingly competitive weeds. Diseases will generally become more problematic over the next century, especially as a result of warmer temperatures. The potential for adaptation will vary strongly by crop type. These results are based on previous work to date and literature reviews. 12

Projected Maximum Weekly Average Water Temperatures – 2040s Salmon Water temperature is already a problem in many WA stream reaches. Exceedences of WQ criteria for temp, especially in summer, will increase with warmer summer temperatures and reduced low flows due to earlier snowmelt. Projected Maximum Weekly Average Water Temperatures – 2040s From the interim report: In the 2001-2006 period, 15% of the stations included in our analysis had an observed maximum weekly average water temperature greater than the 21ºC (70°F) water quality criteria, and all of those stations are located in the interior Columbia Basin. Under the A1B emissions scenario, 2040s August average air temperatures are projected to rise by 2.8ºC (approximately 5.0°F). Using the delta method by assuming an equivalent rise in the annual maximum weekly water temperature results in 49% of these stations exceeding the 21ºC (70°F) criteria, with many recording stations in southwest Washington and the Puget Sound Lowlands and all the stations in the Columbia Basin exceeding the 21ºC (70°F) criteria. Although this approach ignores a range of factors that give rise to the observed heterogeneity in stream temperatures, this simple projection should give a useful preview of the projected stream temperatures we will develop in the next year using the 1/16 degree gridded air temperature fields and empirically-based stream temperature models. The period of maximum temperatures will vary from stream to stream, therefore this figure is generally for summer temperatures and is not tied to a specific month (although most occurred in September). How were these values calculated? We took the average weekly maximum water temperature at each station for 2001-2007 and averaged those max temps at each site. Changes are calculated from this base period. 49% of stations exceed the 21ºC (70°F) water quality criteria (changes relative to 2001-2007) 13

Forests Wildfires are strongly associated with climate, especially in eastside forests. 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. Productivity of Douglas-fir forests is likely to decrease statewide. Supporting text (taken directly from the interim report): 1. Without an increase in summer precipitation (greater than any predicted by climate models), future area burned is very likely to increase. Forests east of the Cascade crest will be most susceptible to larger and more severe fires in a changing climate. 2. Although other insect populations may increase with warmer temperatures, the mountain pine beetle poses the greatest threat of damage to Washington forests over the next several decades because it responds directly to warmer temperatures. Eastside forests dominated by lodgepole pine and possibly ponderosa pine, both host species for the beetle, will be most susceptible in a changing climate. 3. Washington state forests most likely to experience major changes in composition in a changing climate will be those near the lower treeline on the east side (ponderosa pine and Douglas-fir) and at the upper treeline on both sides of the Cascade Crest. 4. The limiting factors for Douglas-fir growth may change from light availability (particularly westside lower elevations) and cold (upper elevations) to water-balance deficit over significant acreage in Washington. The most vulnerable part of the state will initially be montane Douglas-fir stands on the east side, but eventually the more productive commercial forests of the west side. 14

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.

Energy Heating degree days will continue to dominate in the 2020s and 2040s, but cooling degree days become a much more important factor in eastern WA as the region warms. In the Spokane metro area, heating degree days will decline by about 15% in the 2040s compared to the historic condition, but cooling degree days will increase by 88%. 16

Human Health Summer heat waves are expected to increase. Warmer summer air temperatures are likely impact air quality, increasing ozone concentrations and fine particulates Increased temperatures and flooding may alter the habitat and range of disease reservoirs and vectors (e.g., mosquitoes) The most vulnerable populations include infants, children, the elderly, the mentally ill, and the poor 17

The Climate Impacts Group Marketa McGuire Elsner 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 Climate science in the public interest