PNW Climate Change Impacts & PNW Climate Change Impacts & Related StudiesRelated Studies

Marketa McGuire ElsnerClimate Impacts GroupCenter for Science in the Earth SystemJoint Institute for the Study of the Atmosphere and OceanUniversity of Washington

November 28, 2007Public Meeting of the League of Women Voters

Climate science in the public interest

Why Climate Change MattersWhy Climate Change Matters

The PNW’s ecosystems, communities, and economy are sensitive to changes in climate.

Global and regional climate is already changing, and these changes are expected to accelerate in the coming decades.

Significant climate change impacts are projected, and the impacts expected in the next few decades are largely unavoidable.

Local governments are on the front line with respect to dealing with climate impacts.

ObservationsModels using natural forcings onlyModels using natural and anthropogenic forcings

2121stst Century Warming in the PNW Century Warming in the PNW

Precipitation Projections - 21Precipitation Projections - 21stst Century Century

824 snow courses73% – trends

Large – trends PNWSome + trends SW

Trend in Apr 1 Trend in Apr 1 Snowpack Snowpack 1950-20001950-2000

Spring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basins

Snowpack will melt earlier with warmer spring temperatures

Lower Spring SnowpackLower Spring Snowpack

+4°F, +4.5% winter precip

April 1 Snowpack

0

20

40

60

80

100

120

oct nov dec jan feb mar apr may jun jul aug sep

Sim

ulat

ed B

asin

Avg

Run

off (

mm

)

1950

plus2c

Simulated Changes in Natural Runoff Timing in the Simulated Changes in Natural Runoff Timing in the Naches River Basin Associated with 2Naches River Basin Associated with 2°°C WarmingC Warming

Impacts:•Increased winter flow•Earlier and reduced peak flows•Reduced summer flow volume•Reduced late summer low flow

Warmer temperatures: More water, less snow in

winter mid- , low elevations Less water in summer

Increased risk of winter flooding in many basins (changes in urban flooding less clear)

Increased risk of summer drought

Negative impacts on hydropower production, irrigation water supply, instream flow protection

More stress on urban water supplies

Impacts on Water ResourcesImpacts on Water Resources

Overall: climate change will require increasingly complex trade-offs between competing management objectives

Washington State Climate Washington State Climate Impacts AssessmentImpacts Assessment

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

Agriculture

SalmonForest Resources

Coast Lines Energy

Infrastructure

Water Resources

A comprehensive state climate change

assessment that includes the impacts of

global warming

Adaptation / Legal Barriers

Hydrologic Scenarios Database for the Hydrologic Scenarios Database for the Columbia River BasinColumbia River Basin

Working in Coordination With Regional Stakeholders

Planning Framework Incorporating Climate Information and Uncertainty

Ecology BPA NPCC State of OR British Columbia (BC Hydro,

Ministry of Environment)

~20 GCMs 2 Emissions Scenarios 2 Downscaling Approaches

Large Scale Planning Studies WRIA Water Supply Planning Specific Planning Studies

• Motivation for writing grew out of October 2005 King County climate change conference

• Written by the CIG and King County, WA in association with ICLEI – Local Governments for Sustainability

• Written to compliment ICLEI’s “Climate Resilient Communities” Program

• Focused on the process (not a sector), and written for a national audience

www.cses.washington.edu/cig/fpt/guidebook.shtml

Why Climate Change MattersWhy Climate Change Matters

Global and regional climate is already changing

These changes are expected to accelerate in the coming decades

Changes in snowpack and streamflow caused by rising temperatures will have important consequences for resources across the Pacific Northwest

Climate Impacts Group strives to provide information and tools to help planning and adaptation

Climate science in the public interest

More information on PNW climate impacts and planning for climate change is

available from

The Climate Impacts Groupwww.cses.washington.ed/cig

Marketa McGuire Elsnermmcguire@u.washington.edu

Projected range of global-scale warming by the 2090s: 3.2°F-7.2°F

Warming expected through 21st century even if CO2 emissions end today due to persistence of greenhouse gases.

Carbon Dioxide ~60% of warming from GHG 5 to 200 years

Methane ~20% of warming from GHG 8 to 12 years

Nitrous Oxide ~6% of warming from GHG ~120 years

CF4 (Perfluoromethane) >50,000 years

Estimated atmospheric

lifetime of major greenhouse gas

(per molecule)Data source: IPCC 2001

2121stst Century Global Warming Century Global Warming

Regional Impacts• Salmon: increased stress from floods, warm streams, low

summer streamflows

• Forests: increased risk of wildfire, vulnerability to insects, decreased growth & regeneration

• Coasts: inundation, erosion, habitat loss, flooding

• Agriculture: increased production?, decreased irrigation supply, increased heat stress/insects

• Recreation/Tourism: shortened winter ski season (improved access?), summer impacts from forest fires

• Hydropower: increased winter production, lower summer production

Impacts on Other PNW ResourcesImpacts on Other PNW Resources

Overall: climate change will require increasingly complex trade-offs between competing management objectives

On-Line Survey WebsiteOn-Line Survey WebsiteProject ScopeProject Scope

http://cses.washington.edu/cig/http://www.surveymonkey.com/s.aspx?sm=daSOYBVOb238oFy6ia7bcA_3d_3d