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Planning for Planning for Climate ChangeClimate Change in the in the
Pacific NorthwestPacific Northwest
Amy Snover, PhDClimate Impacts Group
Center for Science in the Earth SystemUniversity 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 The Climate Impacts GroupGroup
ColumbiaRiver 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 (CO2 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 2.5-10.4°F by 2100
Source: IPCC TAR 2001
Earth’s Surface Temperature - Earth’s Surface Temperature - Past and FuturePast and Future
1000 2000
+ 10°° F
+ 5°° F
1900 2100
From 1900 to 2000 the planet warmed ~1°F. Global average temperature projected to increase 2.5-10.4°F by 2100.
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 (+2.5-10.4°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
Temperature Precipitation summer winter summer winter low +3.1F +3.2F -7% -2%
mean +4.7F +5.2F +2% +9% high +6.7F +6.7F +9% +22%
Warmer, wetter winters. Warmer summers.
Estimated climate change from 20th 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
summerNaturalized 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
0
100
200
300
400
500
600
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
cfs
Cedar Current ClimateCedar pcm3dec4Cedar echam4dec4Cedar had2dec4Cedar had3dec4
• 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
Puget Sound Region Demand Projections
50
100
150
200
250
300
350
400
450
500
550
Demand Year
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
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
Climate impact onhydrology
Climate impact ondemand
Impact of growth ondemand 2040
Impact of climatechange on 2040
demand andhydrology
Mil
lio
n G
alll
on
s
1952196619681982198719921994
Average Monthly Bull Run Inflows1950-1999
0
200
400
600
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1000
1200
1400
1600
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2200
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Inflo
ws,
cfs
Current ClimatePCM3 2040ECHAM4 2040HadCM2 2040HadCM3 2040
2040s WATER NEEDS IN PORTLAND (OR):
Regional growth: +40 mgdClimate change: +20 mgd
Climate change impacts = 50% of growth impacts
Skiing Later season opening Shorter season More rainy days
4
32
1
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
SalmonSalmon
• 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 2070-2100
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
streamflowWeb 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
http://www.jisao.washington.edu/PNWimpacts
Questions?
