Global Warming and Its impacts on the Pacific Northwest
Global Warming and Its impacts on the Pacific Northwest
Dr. Nathan MantuaUniversity of WashingtonClimate Impacts Group
Dr. Nathan MantuaUniversity of WashingtonClimate Impacts Group
For the NW Straits CommissionThe Skagit Casino and Resort
November 4, 2005
cses.washington.edu/cigcses.washington.edu/cigcses.washington.edu/cigcses.washington.edu/cig
ColumbiaRiver Basin
The The Climate Climate Impacts Impacts GroupGroup
The The Climate Climate Impacts Impacts GroupGroup
A NOAA-funded research and
education team at the University of
Washington
The Greenhouse Effect
The Greenhouse Effect
There is a natural greenhouse effect that warms the earth’s average surface temperature by ~33 C
Pierce
The natural Greenhouse Effect
The natural Greenhouse Effect
Humans are increasing the greenhouse effect by adding greenhouse gases to the atmosphere
• CO2: by 32%
• Methane: by 150%
• Nitrous oxide: by 17%
IPCC 2001
From Jones and Palutikofhttp://www.cru.uea.ac.uk/cru/info/warming/
Global Average Surface Temperatures are
Rising~0.8 C rise in global average temperatures since 1860s
3.6°F
2.7°F
1.8°F
0.9°F
cooler warmer
Temperature trends (°F per century) since 1920
Evidence of warming
Evidence of warming
Ice is melting everywhere
Larsen B Ice shelfAntarctica
January 31, 2002
MODIS dataCourtesy NSIDC
February 17
February 23
March 5
1928
2000
The South Cascade glacier
retreated dramatically in the 20th
century
Courtesy of the USGS glacier
group
Declining April 1 snowpack, 1950-1997
1950-1997 relative trends in April 1 SWE vs DJF temperature
ObsVIC
Stewart et al., 2005Stewart et al., 2005
Spring-pulse dates
Centers of Mass
Western snowfed Western snowfed streamflow has been streamflow has been arriving earlier in arriving earlier in the year in recent the year in recent
decadesdecades
Springpulse
Center time
Figure by Iris Stewart, Scripps Inst. of Oceanog. (UC San Diego)
Natural Climate Influence Human Climate Influence
All Climate Influences
What about the future?
What about the future?
22
Pop-culture
perspectives
• Perhaps this is good fiction, but it is not good science
• Likewise, the Day After Tomorrow scenario might make for a fun movie, but it presents physically impossible impacts of global warming at ridiculous rates of change
21st century Global Average temperature change Scenarios21st century Global Average temperature change Scenarios
IPCC (www.ipcc.ch)
social unknowns and emissions
geophysics
uncertainty
Temperature change, 2071-2100 minus 1961-1990
21st Century PNW Temperature Change Scenarios
Springtime snowpack will decline, especially at the
warmest locations
Springtime snowpack will decline, especially at the
warmest locations
+2.3C,+4.5% winter precip
+ 4.1 + 4.1 ººF (2.3 F (2.3 ººC) C) &&
+ 4.5% winter + 4.5% winter precipitationprecipitation
The coldest locations are less sensitive to
warming
The coldest locations are less sensitive to
warming
+ 4.1°F+ 4.5% winter precip
Runoff patterns are temperature and Elevation
dependent
Runoff patterns are temperature and Elevation
dependent
Oct Feb Jun
Skagit
Puyallup
Skokomish
Oct Feb Jun
Oct Feb Jun
Puget Sound Precip
Oct Feb Jun
1900’s
a warmer climatea warmer climate
Sea Level Rise scenarios depend on regional
tectonics
Sea Level Rise scenarios depend on regional
tectonics•tectonic processes and glacial rebound are causing South Puget Sound to subside and the Olympic Peninsula to uplift
•this means that relative sea level rise will be greatest in South Puget Sound (~3.3ft by 2100), and least near Neah Bay (~1.3ft by 2100)
Climate impacts on salmon must be added to existing stresses across their full life-cycle
HABITAT CHANGE and HABITAT CHANGE and DEGRADATION DEGRADATION
INCLUDING GLOBAL INCLUDING GLOBAL WARMINGWARMING
HATCHERY HATCHERY PRACTICESPRACTICES
HARVEST HARVEST PRACTICESPRACTICES
Impacts are cumulative …
Temperature thresholds for coldwater fish in freshwater
• Warming temperatures will increasingly stress coldwater fish in the warmest parts of our region
A monthly average temperature of 68ºF (20ºC) has been used as an upper limit for resident cold water fish habitat, and is known to stress Pacific salmon during periods of freshwater migration, spawning, and rearing.
+3.4 °F+3.4 °F +4.1 °F+4.1 °F
Climate change impacts on Washington’s forestsClimate change impacts on Washington’s forests
• CO2 fertilization
•
A transient impact
• a longer dry season
• reduced regeneration, increased vulnerability to fires and pests (except in especially cool-wet locations)
• shifts in species ranges
• subalpine forests “invading” alpine meadows; a northward march--or a loss--of species?
Ecosystem thresholds: the case of the Mountain Pine
Beetle
Ecosystem thresholds: the case of the Mountain Pine
Beetle
• a massive outbreak of the mountain pine beetle in BC has killed 100 billion board feet (approx. 9 years of harvest)
• low temperatures (< -10°F) limit beetle activity
• a recent lack of extreme cold, killing temperatures has allowed the beetle to thrive in epidemic numbers
beetle killed pines in BC
Photos from http://www.for.gov.bc.cal
Climate change sharpens the tradeoffs in a world
of multiple stresses
Climate change sharpens the tradeoffs in a world
of multiple stresses• climate change will likely intensify existing conflicts over scarce natural resources
o most of our natural resources are now fully allocated and managers already grapple with difficult tradeoffs
o summer water supplies for in and out of stream uses are especially vulnerable to climate warming
• global warming impacts on the PNW depend on both the climate change and on how we prepare
Choices nowChoices now Reduce emissions - makes a big difference beyond 2050
Prepare for impacts - anticipating change may enhance benefits, minimize risks, and make it more likely to reach planning goals
o Examples: city water supplies, salmon recovery plans, habitat conservation and restoration plans, coastal development …
Main pointsMain points Global climate is changing under human influence
Some effects are already being observed
Future effects a mix of bad and good, and will in part depend on policy decisions now