Research

Integrated Assessment: Current Research

The Washington Climate Change Impacts Assessment

Overview

In July 2007, the Climate Impacts Group (CIG) launched an unprecedented assessment of climate change impacts on Washington State. The Washington Climate Change Impacts Assessment (WACCIA) involved developing updated climate change scenarios for Washington State and using these scenarios to assess the impacts of climate change on the following sectors:

• agriculture,
• coasts,
• energy,
• forests,
• human health,
• hydrology and water resources
• salmon, and
• urban stormwater infrastructure.

Adaptation in each of these sectors was also discussed. Research partners included Washington State University and Pacific Northwest National Laboratory. The assessment was funded by the Washington State Legislature through House Bill 1303.

Key Findings

Key findings from the WACCIA include the following:

• Climate scenarios - Global climate models project increases in average annual Pacific Northwest temperature of 2.0°F by the 2020s, 3.2°F by the 2040s, and 5.3°F by the 2080s (compared to 1970-1999). Projected changes in annual precipitation, averaged over all models, are small (+1 to +2%), but some models project an enhanced seasonal precipitation cycle with changes toward wetter autumns and winters and drier summers. For more details, see Mote and Salathé 2009.
• Regional climate modeling - Modeling of two global climate simulations using the fine-scale Weather and Research Forecasting (WRF) regional climate model suggests that temperature and precipitation projections will vary spatially from the coarse-scale changes projected by global models. The variation can be attributed to the interaction of local terrain and coastlines with changing weather patterns as well as the unique characteristics of the models. Despite this, however, the two simulations modeled with the WRF model show consistent results for projected losses in Washington snowpack and increases in extreme precipitation events. For more details, see Salathé et al. 2009.
• Hydrology - April 1 snowpack is projected to decrease by 28% across the state by the 2020s, 40% by the 2040s, and 59% by the 2080s (relative to the 1916-2006 historical average). As a result, seasonal streamflow timing will likely shift significantly in sensitive watersheds. For more details, see Elsner et al. 2009.
• Water supply: Puget Sound - Puget Sound water supplies will see a shift in the timing of peak river flow from late spring (driven by snowmelt) to winter (driven by precipitation) and reduced levels of summer and fall storage. However, Puget Sound water supply systems will generally be able to accommodate changes through the 2020s in the absence of any significant demand increases. For more details, see Vano et al. 2009(a).
• Water supply: Yakima - The Yakima basin reservoir system will likely be less able (compared to 1970-2005) to supply water to all users, especially those with junior water rights. Without adaptation, shortages would likely occur 32% of years in the 2020s, 36% of years in the 2040s, and 77% of years in the 2080s (compared to 14% of years for the period 1916-2006). Due to lack of irrigation water and more frequent and severe prorating, average production of apples and cherries would likely decline by approximately $23 million (about 5%) in the 2020s and $70 million (about 16%) in the 2080s. For more details, see Vano et al. 2009(b).  
• Energy - Annual hydropower production (assuming constant installed capacity) is projected to decline by a few percent due to small changes in annual stream flow, but seasonal changes will be substantial. On the demand side, population growth is expected to increase winter heating demand even as winter temperatures warm. Summer cooling demand is expected to increase significantly – on the order of 363-555% by the 2040s - due to the combined effects of population growth and warmer summer temperatures. For more details, see Hamlet 2009.
• Agriculture - Assuming no reduction in irrigation supplies, the impact of climate change on apples, potatoes, and wheat in eastern Washington is projected to be mild in the short term (i.e., next two decades), but increasingly detrimental with time, with potential yield losses reaching 25% for some crops by the end of the century. For more details, see Stöckle et al. 2009.
• Salmon - Rising stream temperatures will likely reduce the quality and extent of freshwater salmon habitat. The duration of periods that cause thermal stress and migration barriers to salmon is projected to at least double (low emissions scenario, B1) and perhaps quadruple (medium emissions scenario, A1B) by the 2080s for most analyzed streams and lakes. The greatest increases in thermal stress would occur in the Interior Columbia River Basin and the Lake Washington Ship Canal. For more details, see Mantua et al. 2009.
• Forests - Due to increased summer temperature and decreased summer precipitation, the area burned by fire regionally is projected to double by the 2040s and triple by the 2080s (relative to 1916-2006). The probability that more than two million acres will burn in a given year is projected to increase from 5% (observed) to 33% by the 2080s. Primarily east of the Cascades, mountain pine beetles will likely reach higher elevations and pine trees will likely be more vulnerable to attack by beetles. For more details, see Littell et al. 2009.
• Coasts - Sea level rise will shift coastal beaches inland and increase erosion of unstable bluffs. Major ports likely will be able to accommodate rising sea level at their facilities but adapting low-lying coastal transportation networks that serving port facilities (e.g., trains, highways) will be a significant challenge. Shellfish production in the state will possibly be negatively impacted by increasing ocean temperatures and acidity, shifts in disease and growth patterns, and more frequent harmful algal blooms. For more details, see Huppert et al. 2009.
• Urban stormwater infrastructure - Although few statistically significant changes in extreme precipitation have been observed to date in the Puget Sound, the Spokane area, or Vancouver/Portland, regional climate model simulations generally predict increases in extreme high precipitation over the next half-century, particularly around Puget Sound. In that region, existing drainage infrastructure designed using mid-20th century rainfall records may be subject to rainfall regimes that differ from current design standards. For more details, see Rosenberg et al. 2009.
• Health - Climate change in Washington State will likely lead to significantly more heat and air pollution-related deaths throughout this century. Projected warming would likely result in 101 additional deaths among persons aged 45 and above during heat events in 2025 and 156 additional deaths in 2045 in the greater Seattle area alone (relative to 1980-2006). By mid-century, King County will likely experience 132 additional deaths between May and September annually due to worsened air quality caused by climate change. For more details, see Jackson et al. 2009.
• Adaptation - Preparing for (or adapting to) the impacts of climate change is necessary to minimize the negative consequences, and maximize the benefits, of climate change in Washington State. Navigating Washington's changing future will require regulatory, legal, institutional, and cultural changes to reduce the barriers that limit developing a more climate resilient Washington. Options for adapting to climate change are varied and the choices made by any one community will depend on how climate change may affect a specific community's interests, the resources available to that community, and their risk tolerance. For more details see Whitely Binder et al. 2009.

The WACCIA Report

Final copies of the Washington Climate Change Impacts Assessment chapters are available below for download. Washington Assessment chapters have also been published in a special issue of the journal Climatic Change. Links to the abstracts for those papers are provided below.

The WACCIA Conference

On February 12, 2009, the CIG hosted a one day conference on the results of the Washington Climate Change Impacts Assessment. The conference brought approximately 600 people together to learn about and discuss the implications of the Assessment's findings. Presentations and other materials from the conference are available on the WACCIA conference website.