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