CLIMATE CHANGE IMPACTS IN THE PACIFIC NORTHWEST An Overview Lara Whitely Binder Climate Impacts Group University of Washington Washington Dept of Natural Resources May 24, 2010 Climate science in the public interest

Collective expertise includes : Statistical and dynamical downscaling of global climate model projections Macro and fine scale hydrologic modeling Water resources impacts assessment Terrestrial and aquatic ecosystems impacts assessment Adaptation planning and outreach Objectives Increase regional resilience to climate variability and change Produce science useful to (and used by!) the decision making community An integrated research team studying the impacts of climate variability and climate change in the PNW and western US The Climate Impacts Group

GLOBAL CLIMATE CHANGE Setting the Stage for Pacific Northwest Climate Change

+35% Figure sources: IPCC WG Human activities have increased the concentration of major greenhouse gases since % +18%

Figure source: IPCC 2007 WG1, Summary for Policy Makers Range based on assumptions about global population growth, changes in technology, Earth’s sensitivity to greenhouse gas concentrations Projected Global-Scale Warming IPCC’s “likely” (>66%) range of global-scale warming, 2090s: 2-11 ° F IPCC “Best estimate” range, 2090s: 3.2°F-7.2°F

IPCC Spatial Distribution of Warming, SRES A2 Scenario

Projected Increases in Annual PNW Temperature 2020s 2040s 2080s °F°F°C°C +5.3°F ( °F) +3.2°F ( °F) +2.0°F ( °F) * Relative to average Mote and Salathé, 2009 All modeled scenarios project warming across all seasons with the greatest warming occurring during summer months. Historic

Projected Changes in Annual PNW Precipitation While there is significant variability across models, wetter winters and drier summers are expected. Changes in annual total precipitation averaged over all models are small (+1-2% by the 2040s). Mote and Salathé, 2009 Historic * Relative to average

What About Changes in Extreme Precipitation? Few statistically significant changes in extreme precipitation have been observed in the last 50 years, with the possible exception of the Puget Sound More intense precipitation projected by regional climate model but distribution is highly variable; substantial changes (+5-10%) only over the North Cascades and northeastern Washington. – The projections vary by model and region – Actual changes may be difficult to distinguish from natural variability. – Still need the conditions that bring the storms to a given location (Rosenberg et al. 2009, Salathé et et al. 2009)

PROJECTED CHANGES TO PACIFIC NORTHWEST HYDROLOGY Pacific Northwest Climate Change Impacts

Expected 21 st century changes in temperature and precipitation will transform the hydrologic behavior of many mountain watersheds in the West.

Low Medium -29% -44% -65% -27% -37% -53% Key Impact: Loss of April 1 Snow Cover Why? Spring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basins. Also, snowpack will melt earlier with warmer spring temperatures Elsner et al. 2009

Projected Changes in Spring Snowpack by Elevation Band

Impacts to Seasonal Streamflow Mixed Rain/Snow (Transient)Rain Dominant Snowmelt Dominant Historical & Projected 21 st Century Flows Medium (A1B) Scenario Depending on basin type: Increasing winter flows (re: more winter precip; shift to more rain at mid elev.) Earlier, lower peak runoff (re: warmer spring temps; lower spring snowpack) Lower summer streamflow (re: warmer summer temps; earlier peak runoff) Elsner et al. 2009

Mantua et al. 2009

PROJECTED CHANGES TO AQUATIC AND TERRESTRIAL ECOSYSTEMS Pacific Northwest Climate Change Impacts

Models project more winter flooding, particularly in temperature sensitive “transient” (rain/snow mix) river basins that are common in the Cascades Mantua et al (WACCIA report)

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

Impacts will vary depending on life history and watershed types In Washington State, for example: Low flows+warmer water = increased pre-spawn mortality for summer run salmon and steelhead – Clear indications for increased stress on Columbia Basin sockeye, summer steelhead, summer Chinook, also Lake Washington sockeye and Chinook Increased winter flooding in Puget Sound streams – an increased stressor on egg-to-fry survival rates for fall spawners, and overwinter survival rates for yearling parr (steelhead, coho, and stream-type chinook) Mantua et al. 2009

Increased summer temperatures lead to increased water deficit and increased climatic stress for trees. This contributes to: Changes in productivity Increase in disturbance from insects Increasing forest fire risk Changes in species distributions “Stress complexes” (e.g., fire, insects) will be strong agents of landscape change by midcentury Impacts on PNW Forests

Changes in climate suitability for Douglas-fir distribution: 2060s Littell et al * *Modeled current distribution Data: Rehfeldt et al. High percents: high likelihood the climate remains suitable Low percents: indicate low climate suitability Regeneration, productivity are likely to decrease

Projected suitability changes: Lodgepole Pine, Current Climate Data: Rehfeldt et al. Littell et al. 2009

Projected suitability changes: Lodgepole Pine, 2060s Data: Rehfeldt et al. Littell et al. 2009

Projections of Future Regional Area Burned Historical average: 425,000 acres –2020s: 0.8 million –2040s: 1.1 million –2080s: 2.0 million Probability of a year >> 2 million acres: –Historical: 5% –2020s: 5% (1 in 20) –2040s: 17% (~1 in 6) –2080s: 47% (~1 in 2) DRIVERS: Warmer summer temperatures Earlier spring snowmelt (likely) Reduced soil moisture Stress from insects such as the Mountain Pine Beetle Littell et al. 2009

Northern Goshawk (HADCM3 A1B) stable expansion contraction Slide courtesy of Josh Lawler, UW

Projected Species Turnover Aggregated for 3,000 species % change Slide courtesy of Josh Lawler, UW

Climate Change Impacts on Pika Distribution three climate change scenarios high, medium, low warming substantial reduction in area of distribution decreases by 81-98% increasingly fragmented distribution Trook and Hicke, in revision Slide courtesy of Jeff Hicke

PROJECTED IMPACTS TO PNW COASTAL AND MARINE ENVIRONMENTS Pacific Northwest Climate Change Impacts

Major determinants of SLR at the regional scale: Global drivers: Thermal expansion of the ocean; Melting of land-based ice; +7 to +23 inches globally by 2100 (IPCC 2007) Relative Sea Level Rise (SLR) Regional drivers: Atmospheric dynamics (e.g., wind-driven “pile- up”) Tectonic processes (subsidence and uplift) Impacts (+/-) vary by location

Sea Level Rise Medium estimates of sea level rise in Washington for 2100: +2” for the NW Olympic Peninsula +11” for the central/southern coast +13” for Puget Sound Increased storm surge and related episodic flooding will present a greater near-term challenge. Rising sea levels will increase the risk of flooding, erosion, and habitat loss along much of the Pacific Northwest coastline. 3” 6” 30” 50” ” 40” 20” 10” 6” Projected sea level rise (SLR) in Puget Sound relative to , in inches. Shading roughly indicates likelihood.

For much of Puget Sound… A one foot of sea level rise turns a 100 year flood event into a 10 year event. A two foot sea level rise turns a 100 year flood event into an annual event. Changing Coastal Flood Risk Increased storm surge and related episodic flooding will present a greater near-term challenge. Numbers and photos courtesy of Hugh Shipman, Washington Dept. of Ecology

Alki Beach, West Seattle, January 21, 2010 Photo by Hugh Shipman Source: Washington Dept of Ecology

NWF (2007) evaluation of impacts to coastal habitat at 11 locations in Washington and Oregon from 27.3” of sea level rise: 65% loss of estuarine beaches 61% loss of tidal swamps 44% loss of tidal flats 52% conversion of brackish marsh to tidal flats, transitional marsh, and saltmarsh Loss could affect availability of this habitat for spawning, juvenile rearing, migratory and over-wintering stopovers, commercial shellfish production Impacts to PNW Coastal Habitats National Wildlife Federation (2007), Sea-level Rise and Coastal Habitats in the Pacific Northwest An Analysis for Puget Sound, Southwestern Washington, and Northwestern Oregon

Ocean Acidification CO 2 is corrosive to the shells and skeletons of many marine organisms Photo source: Missouri Botanical Gardens Corals Calcareous plankton Slide source: NOAA PMEL

Reduced calcification rates for calcifying (hard-shelled) organisms and physiological stress Shifts in phytoplankton diversity and changes in food webs Reduced tolerance to other environmental fluctuations Potential for changes to fitness and survival, but this is poorly understood What are the biological implications of ocean acidification? Barrie Kovish Pacific Salmon Coccolithophores Vicki Fabry Pteropods Copepods (Slide provided by Dick Feely, NOAA)

Concluding Points Global and regional climate is already changing, and these changes are expected to accelerate in the coming decades Major impact pathways include: Increasing temperatures Declining spring snowpack Shifts in streamflow timing Changes in disturbance regimes (insects, fire) Sea level rise Ocean acidification(?)

Concluding Points The future will not present itself in a simple, predictable way. Natural variations will still be important for climate change in any location. The results presented here are projections, not predictions. Pacific Northwest ecosystems are sensitive to changes in climate. Contributing factors include relatively low elevation of the Cascades and Olympics; presence of multiple stresses on many human and natural systems.

More information on PNW climate impacts and planning for climate change is available from The Climate Impacts Group Washington Climate Change Impacts Assessment