Planning for Climate Change in the Pacific Northwest Amy Snover, PhD Climate Impacts Group Center for Science in the Earth System University of Washington

Goal: to increase the region’s resilience to climate variations and climate change Areas of study: Water resources Salmon Forests Coasts The Climate Impacts Group Columbia River Basin - The past is the key to the future -

Considerations for management Responsible management looks forward... Needs of a growing population Environmental stewardship Climate change Outline of Talk: Brief review of climate change Implications for Pacific Northwest climate Consequences for PNW natural resources Application to regional policy & planning

Brief Review of Climate Change Carbon dioxide and other greenhouse gases warm the planet Greenhouse gases have been increasing (CO 2 up 30%) and will increase for a long time as a result of human activities The planet has warmed ~1°F since 1900, in part due to human activities Further warming of °F by 2100

Source: IPCC TAR 2001 Earth’s Surface Temperature - Past and Future ° + 10 ° F ° + 5 ° F From 1900 to 2000 the planet warmed ~1°F. Global average temperature projected to increase °F by Very significant change from historical perspective.

Future Climate Change Earth’s average temperature projected to increase during the 21st century at a rate 2-10 times that observed in the 20th century ( °F by 2100) Expect additional changes in climate (precipitation, storm tracks) Global average sea level projected to rise 4-35 inches by 2100 These changes will have far-reaching consequences

Warmer, wetter winters. Warmer summers. Estimated climate change from 20 th century to the 2040s using 8 climate model scenarios (“summer”=April-September, “winter” = October-March). Climate change in the PNW

PNW Temperature: Past and future

The Main Impact: Less Snow April 1 Columbia Basin Snow Extent ~ 2045Historical Average~ 2025

Less snow, earlier melt:  More water in winter  Less water in summer Naturalized Columbia River flow - the Dalles, OR.  winter flooding Changes in amount & timing of peak flows  spring/summer water temperature  spring/summer flows Changes in the Water Cycle Columbia Basin: Decreased spring/summer flows -- salmon & irrigation Increased competition & conflict among uses More $$ summer drought Increased vulnerability

Planning for Climate Change: Municipal water supply More winter streamflow Less spring/summer streamflow For western Washington rivers (Sultan, Tolt, Cedar, Green) in the 2040s: Winter: +30 to 40% Summer: -20 to –30%

Planning for Climate Change: Municipal water supply Demand increases with: population growth warmer temperatures Total Pierce Snohomish King Puget Sound demand changes from population projections More winter streamflow Less spring/summer streamflow Increased demands

More winter streamflow Less spring/summer streamflow Increased demands Planning for Climate Change: Municipal water supply 2040s WATER NEEDS IN PORTLAND (OR): Regional growth: +40 mgd Climate change: +20 mgd Climate change impacts = 50% of growth impacts

Skiing  Later season opening  Shorter season  More rainy days Snoqualmie (3000’) Stevens (4000’) Mission Ridge (4500’) Schweitzer (4000’) Changes in the Water Cycle Landslides  Increased frequency / magnitude  Exacerbated by sea level rise around Puget Sound

Current Conditions

Salmon Climate influences habitat quality (stream, estuarine, and ocean habitat) Future scenarios indicate increased climate stress in the freshwater environment –Winter: floods –Summer/Fall: low flows & high temperatures Future changes in crucial coastal and ocean habitat are uncertain

Big Questions: Seasonality of precipitation change CO2 fertilization effect Forests Future vegetation changes unclear Continued forest encroachment into alpine meadows Overall forest die- back or expansion?? Vegetation Carbon Change by

Preparing for a changing climate...

Consider climate a component of any long-term plan Water: increase supply, decrease demand, increase management flexibility Salmon: promote biodiversity by increasing healthy and connected habitat Forests: maintain a full range of biodiversity Becoming climate-wise: water, salmon, forests

Tools for Planning  Working with the cities of Portland & Seattle and watershed planning leads under the 1988 Washington State Watershed Planning Program  Developing new tools for planning:  Detailed projections of potential scenarios  low tech/low cost vulnerability assessments Bringing a global issue to the local level

Planning for climate change: Scenarios of future streamflow Web based streamflow scenario tool provides climate change information, including free access to streamflow scenarios and data. Partners: Northwest Power Planning Council Idaho Dept of Water Resources

Some global warming is very likely (1-4°F by 2040s) Regional warming likely to be faster than global warming (3-6°F by 2040s) In the PNW, climate change will: –Reduce winter snowpack & summer streamflow –Increase winter flooding, alter the amount and timing of streamflows with consequences for urban and irrigation water supplies, hydropower production –Negatively affect salmon habitat, alter forest & coastal ecosystems and exacerbate some coastal hazards Knowledge & tools exist to support planning now. Summary

Resources Global and National Assessments (based on thousands of peer-reviewed papers): IPCC reports in 2001, 1996, 1990 National Academy of Sciences 2001 National Resource Council 2000 U.S. National Assessment 2001 Regional Assessments: The Climate Impacts Group, UW

Questions?