Washington State Climate Change Impacts Assessment: HB 1303 Key Findings

1. Washington State Climate Change Impacts Assessment: HB 1303 Key Findings UW Climate Impacts Group Marketa McGuire Elsner Jeremy Littell JISAO CSES Climate Impacts Group University of Washington Washington State University Pacific Northwest National Laboratory Climate science in the public interest

2. Project Team • Forests • (D. McKenzie, J. Littell) • CIG, UW, USFS, Univ. ID • Coasts • (D. Huppert) • CIG, UW • Urban Stormwater Infrastructure • (A. Steinemann, D. Booth) • UW, Stillwater Sciences, King Co. Water and Land Resources Div., Northwest Hydraulic Consultants • Human Health • (R. Fenske) • UW, WSU, Institute for Chemical Process and Envir. Tech. - Canada, CA Air Resources Board • Adaptation • (L. Whitely-Binder) • CIG, UW • Scenarios • (E. Salathé, P. Mote) • CIG, UW, PNNL • Hydrology and Water Resources • (D. Lettenmaier, M. Elsner) • CIG, UW • Energy – Hydropower • (A. Hamlet) • CIG, UW • Agriculture & Economics (Stockle, Scott) • WSU, USDA ARS, PNNL • Salmon • (N. Mantua) • CIG, U

3. Assessment Overview:Study Region

4. Scientific progress, assessment limitations • Progress: • Vertical integration of climate change projections • Wide range of research areas • Narrowing of uncertainty with many climate models • Quantified impacts and ranges for decision making • Limitations: • Modeling climate variability (interannual, decadal) • Interactions or synergies between impacts • Uncertainty in climate and projections • There may be thresholds we have yet to understand

5. Projected Increases in Annual PNW Temperature * Compared with 1970-1999 average 2080s 2040s 2020s +5.9°F +3.5°F +2.2°F °C °F Mote and Salathé, 2009

6. Projected Changes in Annual Precipitation * Compared with 1970-1999 average Changes in annual precipitation averaged over all models are small but some models show large seasonal changes, especially toward wetter autumnsand winters and drier summers. Mote and Salathé, 2009

7. Regional climate model projections Salathé et al, 2009

8. Hydrology and water resources 37-44% change (B1/A1B) * Compared with 1916-2006 average Elsner et al. 2009

9. Mantua et al. 2009

10. Yakima Economics - Production Value 2020s 2040s 2080s • Reservoir system will be less able to supply water to all users, especially those with junior water rights. • Junior and senior water user averaged, impacts include CO2 fertilization • Production decreases by 5% in 2020s, 16% in 2080s (relative to historical) • Production values are buffered somewhat by price increases and largely unchanged production on senior water user lands Vano et al. 2009b

11. Puget Sound Basinmunicipal supply - current demand 1% 7% 0% Tacoma, water allocations closer to current system capacity • Municipal and Industrial, reliability measures differ across systems • With current demands, system reliability able to accommodate changes (A1B) • With demand increases, system reliability reduced, conservation measures matter • Note: simulations do not include adaptation Everett, largest system capacity * Projections compared to water year 1917-2006 average Vano et al. 2009a

12. Energy • Annual hydropower production is projected to decline by a few percent due to small changes in annual flow, but seasonal changes will be substantial. • Winter hydropower production is projected to increase by about 0.5-4.0% by the 2020s, 4.0-4.2% by the 2040s, and 7%-10% by the 2080s (compared to water year 1917-2006) • Summer energy production is projected todecline by 10% by the 2020s, 15% by the 2040s, and 20% by the 2080s. At the same time summer cooling demands may increase by 400% Hamlet et al. 2009

13. Energy Changes in system-wide hydropower production in the Columbia system for three future time frames: large declines in summer, slight increases in winter. Hamlet et al. 2009

14. Agriculture • Given sufficient irrigation, the projected impact of climate change on eastern Washington agriculture is unlikely to be severe. Likely changes in yields from climate alone are increases in winter wheat (2-8% by the 2020s), decreases in irrigated potatoes (15% by the 2040s) and decreases in apples (3% by the 2040s). • However, the combination of warming and elevated CO2 could provide significant potential benefits that offset these declines. There is some uncertainty about whether the CO2 effect is transient, but for well managed crops in eastern WA, the beneficial effect of elevated CO2 will most likely be positive. Stöckle et al. 2009

15. Salmon and Ecosystems • Rising stream temperature will reduce the quality and quantity of freshwater salmon habitat substantially. • The duration of temperatures causing thermal migration barriers and extreme thermal stress (where weekly water temperatures exceed 70°F) are predicted to quadruple by the 2080s. • Water temperatures for Western Washington stations are generally cooler, and predicted impacts on thermal stress are significant but less severe. Mantua et al. 2009

16. Salmon and Ecosystems August Mean Surface Air Temperature and Maximum Stream Temperature 2040s medium (A1B) Historical (1970-1999) * Projections are compared with 1970-1999 average Mantua et al. 2009

17. Forests • The area burned by fire regionally (in the U.S. Columbia Basin) is projected to double or triple (medium scenario, (A1B)), from about 172,000 ha annually (1916-2006) to 0.3 million ha in the 2020s, 0.5 million ha in the 2040s, and 0.8 million ha in the 2080s. • Due to climatic stress on host trees, mountain pine beetle outbreaks are projected to increase in frequency and cause increased tree mortality. Climatically suitable habitat for pine species susceptible to mountain pine beetle is likely to decline but increase in elevation by the 2040s. Littell et al. 2009

18. Forests Current 2060s Changes in the potential climatically suitable range of lodgepole pine (Data: Rehfeldt et al. 2006, multiple IPCC scenarios). Littell et al. 2009

19. Coasts • A previous study involving the Climate Impacts Group found that sea level rise in Puget Sound might be as little as 6” or as much as 50” by 2100. • 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 will possibly be negatively impacted by increasing ocean temperatures and acidity, shifts in disease and growth patterns, and more frequent harmful algal blooms (HAB). Huppert et al. 2009

20. Urban Stormwater Infrastructure • Drainage infrastructure designed using mid-20th century rainfall records may be subject to a future rainfall regime that differs from current design standards. Results from regional climate models suggest increased extreme rainfall in late autumn in western Washington. • Hydrologic modeling of two urban creeks in central Puget Sound suggest overall increases in peak annual discharge over the next half-century, but only those projections resulting from one of the two RCM simulations are statistically significant. Magnitudes of projected changes vary widely, depending on the particular basin under consideration and the choice of the underlying global climate model. Rosenberg et al. 2009

21. Changes in Flood Risks • Floods in western WA will likely increase in magnitude due to the combined effects of warming and increasingly intense winter storms. • In other parts of the State, changes in flooding are smaller, and in eastern WA projected reductions in flood risk are common due to loss of spring snow cover. Mantua et al. 2009

22. Human Health • In Washington, climate change will lead to larger numbers of heat-related deaths due mainly to hotter summers and population growth. For example in Seattle a medium climate change scenario projects 101 additional deaths for people over 45 by 2025 and another 50% increase by 2045 • 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. Jackson et al. 2009

23. Human Health Jackson et al. 2009 Percent Increase in Risk of Death, and Number of Deaths Each Day for All Non-Traumatic Causes by Heat Event Duration, Greater Seattle Area, 1980-2006.

24. Climate change impacts over the next few decades are virtually certain. Impacts beyond this timeframe will be greatly influenced by how successfully we reduce greenhouse gas concentrations both in the near-term and over time. State and local governments, businesses, and residents are on the “front line” when it comes to dealing with climate change impacts. Decisions with long-term impacts are being made every day, and today’s choices will shape tomorrow’s vulnerabilities. Adaptation Options and Opportunities Whitely Binder et al. 2009

25. Conclusions Adaptation to climate change impacts is necessary because the projected impacts within and across sectors are large. To the extent that it can be identified, quantified, and mitigated, uncertainty is a component of planning, not a reason to avoid planning. Many sectors report different impacts in different systems (e.g., snowpack response at low vs. high elevations, fire response in the western Cascades vs. Blue Mountains, different species of salmonids, different crops etc.), but the natural spatial and temporal complexity of these systems is a key part of planning for the future. By understanding the direction and magnitude of projected climate changes and their impacts, we can better manage risks and capitalize on opportunities to reduce impacts.

27. JISAO CSES Climate Impacts Group The Climate Impacts Group www.cses.washington.ed/cig UW Climate Impacts Group Climate science in the public interest