CLIMATE CHANGE IMPACTS IN THE PACIFIC NORTHWESTAn Overview

Lara Whitely BinderLara Whitely BinderClimate Impacts GroupClimate Impacts Group

University of Washington University of Washington

Washington Dept of Natural Washington Dept of Natural ResourcesResources

May 24, 2010May 24, 2010Climate science in the public interest

Collective expertise includes:

• Statistical and dynamical downscaling of global climate model projections

• Macro and fine scale hydrologic modeling• Water resources impacts assessment• Terrestrial and aquatic ecosystems impacts assessment • Adaptation planning and outreach

Objectives • Increase regional resilience to climate variability and change

• Produce science useful to (and used by!) the decision making community

An integrated research team studying the impacts of climate variability and climate change in the PNW and western US

The Climate Impacts Group

GLOBAL CLIMATE CHANGESetting the Stage for Pacific Northwest Climate Change

+35%

Figure sources: IPCC WG1 2007

Human activities have increased the concentration of major greenhouse gases since 1750.

+142%+18%

Figure source: IPCC 2007 WG1, Summary for Policy Makers

Range based on assumptions about global population growth, changes in technology, Earth’s sensitivity to greenhouse gas concentrations

Projected Global-Scale Warming

IPCC’s “likely” (>66%) range of global-scale

warming, 2090s: 2-11°F

IPCC “Best estimate” range, 2090s:

3.2°F-7.2°F

Figure SPM.6IPCC 2007

2020-2029 2090-2099

Spatial Distribution of Warming, SRES A2 Scenario

Projected Increases in Annual PNW Temperature

2020s2040s

2080s

°F°C

+5.3°F (2.8-9.7°F)

+3.2°F (1.6-5.2°F)+2.0°F

(1.1-3.4°F)

* Relative to 1970-1999 average

Mote and Salathé, 2009

All modeled scenarios project warming across all seasons with the greatest warming occurring during summer months.

Historic

Projected Changes in Annual PNW Precipitation

While there is significant variability across models, wetter winters and drier summers are expected. Changes in annual total precipitation averaged over all models are small (+1-2% by the 2040s).

Mote and Salathé, 2009

Historic

* Relative to 1970-1999 average

What About Changes in Extreme Precipitation?

• Few statistically significant changes in extreme precipitation have been observed in the last 50 years, with the possible exception of the Puget Sound

• More intense precipitation projected by regional climate model but distribution is highly variable; substantial changes (+5-10%) only over the North Cascades and northeastern Washington.

– The projections vary by model and region– Actual changes may be difficult to distinguish from

natural variability. – Still need the conditions that bring the storms to a

given location

(Rosenberg et al. 2009, Salathé et et al. 2009)

PROJECTED CHANGES TO PACIFIC NORTHWEST HYDROLOGY

Pacific Northwest Climate Change Impacts

Expected 21st century changes in

temperature and precipitation will

transform the hydrologic behavior of

many mountain watersheds in the

West.

Low

Med

ium

-29% -44% -65%

-27% -37% -53%

Key Impact: Loss of April 1 Snow Cover

Why? Spring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basins. Also, snowpack will melt earlier with warmer spring temperatures

Els

ner e

t al.

2009

Elsner et al. 2009

Projected Changes in Spring Snowpack by Elevation Band

Impacts to Seasonal Streamflow

Mixed Rain/Snow (Transient) Rain Dominant Snowmelt Dominant

Historical & Projected 21st Century FlowsMedium (A1B) Scenario

Depending on basin type:• Increasing winter flows (re: more winter precip; shift to more rain at mid elev.)• Earlier, lower peak runoff (re: warmer spring temps; lower spring snowpack)• Lower summer streamflow (re: warmer summer temps; earlier peak runoff)

Elsner et al. 2009

Mantua et al. 2009

PROJECTED CHANGES TO AQUATIC AND TERRESTRIAL ECOSYSTEMS

Pacific Northwest Climate Change Impacts

Models project more winter flooding, particularly in temperature sensitive “transient” (rain/snow mix) river basins that are common in the Cascades

Mantua et al. 2009 (WACCIA report)

Salmon and EcosystemsAugust Mean Surface Air Temperature and Maximum Stream Temperature

Historical (1970-1999) 2040s medium (A1B)

* Projections are compared with 1970-1999 averageMantua et al. 2009

Impacts will vary depending on life history and watershed types

In Washington State, for example:

• Low flows+warmer water = increased pre-spawn mortality for summer run salmon and steelhead – Clear indications for increased stress on

Columbia Basin sockeye, summer steelhead, summer Chinook, also Lake Washington sockeye and Chinook

• Increased winter flooding in Puget Sound streams– an increased stressor on egg-to-fry survival

rates for fall spawners, and overwinter survival rates for yearling parr (steelhead, coho, and stream-type chinook)

Mantua et al. 2009

Increased summer temperatures lead to increased water deficit and increased climatic stress for trees. This contributes to:

• Changes in productivity • Increase in disturbance from insects• Increasing forest fire risk• Changes in species distributions

“Stress complexes” (e.g., fire, insects) will be strong agents of landscape change by midcentury

Impacts on PNW Forests

Changes in climate suitability for Douglas-fir distribution: 2060s

Littell et al. 2009

*

*Modeled current distribution

Dat

a: R

ehfe

ldt e

t al.

High percents:high likelihood

the climate remains suitable

Low percents: indicate low

climate suitability

Regeneration, productivity are

likely to decrease

Projected suitability changes: Lodgepole Pine, Current Climate

Data: Rehfeldt et al.

Littell et al. 2009

Projected suitability changes: Lodgepole Pine, 2060s

Data: Rehfeldt et al.

Littell et al. 2009

Projections of Future Regional Area Burned

• Historical average: 425,000 acres– 2020s: 0.8 million– 2040s: 1.1 million– 2080s: 2.0 million

• Probability of a year >> 2 million acres:– Historical: 5%– 2020s: 5% (1 in 20)– 2040s: 17% (~1 in 6)– 2080s: 47% (~1 in 2)

DRIVERS:

•Warmer summer temperatures•Earlier spring snowmelt (likely)•Reduced soil moisture•Stress from insects such as the Mountain Pine Beetle

Littell et al. 2009

Northern Goshawk (HADCM3 A1B)

stable

expansion

contraction

Slide courtesy of Josh Lawler, UW

Projected Species TurnoverAggregated for 3,000 species

% change

Slide courtesy of Josh Lawler, UW

Climate Change Impacts on Pika Distribution

• three climate change scenarios

• high, medium, low warming

• substantial reduction in area of distribution

• decreases by 81-98%

• increasingly fragmented distribution

Trook and Hicke, in revisionSlide courtesy of Jeff Hicke

PROJECTED IMPACTS TO PNW COASTAL AND MARINE ENVIRONMENTS

Pacific Northwest Climate Change Impacts

Major determinants of SLR at the regional scale:Major determinants of SLR at the regional scale:

Global drivers:• Thermal expansion of the ocean; • Melting of land-based ice; +7 to +23 inches globally by 2100 (IPCC 2007)

Relative Sea Level Rise (SLR)

Regional drivers:• Atmospheric dynamics (e.g., wind-driven “pile-

up”)• Tectonic processes (subsidence and uplift)Impacts (+/-) vary by location

Sea Level Rise

Medium estimates of sea level rise in Washington for 2100:

+2” for the NW Olympic Peninsula +11” for the central/southern coast+13” for Puget Sound

Increased storm surge and related episodic flooding will Increased storm surge and related episodic flooding will present a greater near-term challenge. present a greater near-term challenge.

Rising sea levels will increase the risk of flooding, erosion, and habitat loss along much of the Pacific Northwest coastline.

3”6”

30”

50”

2050 2100

13”13”

40”

20”

10”6”6”

Projected sea level rise (SLR) in Puget Sound relative to 1980-1999, in inches. Shading roughly indicates likelihood.

For much of Puget Sound…

• A one foot of sea level rise turns a 100 year flood event into a 10 year event.

• A two foot sea level rise turns a 100 year flood event into an annual event.

Changing Coastal Flood Risk

Increased storm surge and related episodic flooding will present a greater near-term challenge.

Numbers and photos courtesy of Hugh Shipman, Washington Dept. of Ecology

Alki Beach, West Seattle, January 21, 2010 Alki Beach, West Seattle, January 21, 2010 Photo by Hugh ShipmanPhoto by Hugh Shipman

Source: Washington Dept of EcologySource: Washington Dept of Ecology

NWF (2007) evaluation of impacts to coastal habitat at 11 locations in Washington and Oregon from 27.3” of sea level rise:

•65% loss of estuarine beaches•61% loss of tidal swamps•44% loss of tidal flats•52% conversion of brackish marsh to tidal flats, transitional marsh, and saltmarsh

Loss could affect availability of this habitat for spawning, juvenile rearing, migratory and over-wintering stopovers, commercial shellfish production

Impacts to PNW Coastal Habitats

National Wildlife Federation (2007), Sea-level Rise and Coastal Habitats in the Pacific NorthwestAn Analysis for Puget Sound, Southwestern Washington, and Northwestern Oregon

Ocean AcidificationOcean Acidification CO2 is corrosive to the shells and skeletons of many

marine organisms

Photo source: Missouri Botanical Gardens

CoralsCorals Calcareous planktonCalcareous plankton

Slide source: NOAA PMEL

• Reduced calcification rates for calcifying (hard-shelled) organisms and physiological stress

• Shifts in phytoplankton diversity and changes in food webs

• Reduced tolerance to other environmental fluctuations

• Potential for changes to fitness and survival, but this is poorly understood

What are the biological implications of What are the biological implications of ocean acidification?ocean acidification?

Barr

ie K

ovis

h

Pacific Salmon

Coccolithophores

Vick

i Fab

ry

Pteropods

Copepods

ARCO

D@im

s.uaf

.ed

u

(Slide provided by Dick Feely, NOAA)

Concluding PointsGlobal and regional climate is already

changing, and these changes are expected to accelerate in the coming decades

Major impact pathways include:• Increasing temperatures• Declining spring snowpack• Shifts in streamflow timing • Changes in disturbance regimes (insects, fire)• Sea level rise• Ocean acidification(?)

Concluding PointsThe future will not present itself in a simple,

predictable way. • Natural variations will still be important for

climate change in any location. • The results presented here are projections, not

predictions.

Pacific Northwest ecosystems are sensitive to changes in climate. Contributing factors include relatively low elevation of the Cascades and Olympics; presence of multiple stresses on many human and natural systems.

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

The Climate Impacts Group

www.cses.washington.edu/cig

Washington Climate Change Impacts Assessment

http://cses.washington.edu/cig/res/ia/waccia.shtml