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A multi-model integrated assessment of the impacts of climate change
in Washington State
Marketa M.
1
Elsner ,
Lan
2
2
Cuo , A.F.Hamlet ,
Dennis P.
1,2
Lettenmaier ,
Edward L.
1
Miles
1. JISAO/CSES Climate Impacts Group, Box 354235, University of Washington, Seattle, WA 98195
2. Department of Civil and Environmental Engineering, Box 352700, University of Washington, Seattle, WA 98195
AGU Annual Fall Meeting, San Francisco, CA. Dec 15-19, 2008
1. Abstract
In April 2007, the State of Washington passed legislation mandating a
comprehensive statewide assessment of the impacts of climate change over the
next 100 years. The Climate Impacts Group (CIG) at the University of Washington
Joint Institute for the Study of the Atmosphere and Ocean (JISAO) is working with
Washington State University, Pacific Northwest National Laboratory, and state
agencies to perform an integrated assessment on the effects of climate change for
eight statewide sectors: public health, agriculture, the coastal zone, forest
ecosystems, salmon, infrastructure, energy, and water supply and management.
An additional Climate Scenarios Working Group serves the eight other sectors by
providing projections of future regional climate, downscaled to 1/16th degree
spatial resolution over the state of Washington. We utilize projections from A1B
and B1 greenhouse gas emissions scenarios, as simulated by the full suite of 20
GCMs, archived in the 2007 Fourth Assessment Report of the IPCC. In this
approach, we apply 40 ensembles of statistically downscaled future climate to
drive hydrologic model simulations. Each sector incorporates the projections of
climatic and hydrologic variables in their evaluations of the impacts of climate
change. Here we present impacts on hydrologic variables (such as snowpack and
streamflow), as well as related implications for several of the sectors listed above,
over the State of Washington for three periods: the 2020s, 2040s and 2080s. We
also discuss CIG’s collaboration with multi-stakeholder adaptation working groups
to identify potential barriers to adaptation and strategies to address the projected
impacts in each sector.
2. Background and Study Approach
Figure 2.1: Map of Pacific Northwest (Columbia River
Basin plus coastal drainages) and Washington State.
In 2007, the State Legislature of
Washington passed HB 1303 which
mandated the preparation of a
comprehensive assessment of the
impacts of climate change on the State
of Washington, with focus on the next 50
years. The Climate Impacts Group (CIG)
at the University of Washington, in
cooperation with two state agencies, is
conducting an integrated assessment
which focuses on the impacts of climate
change in relation to public health,
agriculture, the coastal zone, forest
ecosystems, infrastructure, and water
supply and management.
3. Impacts on Washington Climate and Natural and Human Resources
Climate change will continue to cause significant changes in temperature &
precipitation across Washington State. Based on simulations from 20 Global
Climate Models (GCMs) and 2 emissions scenarios (A1B and B1), we find:
• Annual temperature
will increase
approximately 0.3°C,
or roughly 0.5°F, per
decade over the next
50 years.
• The greatest warming
is predicted for
summer months.
• The range of
precipitation could
increase or decrease
but the projected
mean change is small.
Figure 3.1: Projected change in seasonal and annual temperature (top) and precipitation
(bottom) in the Pacific Northwest. B1 and A1B emissions scenarios represent the range of
possible Greenhouse Gas projections for the 20 GCM ensembles.
• There is considerable
spread among models,
but there is slightly
greater likelihood of
modest increases in
winter and modest
decreases in summer.
Hydrology / Water Resources
2400mm
10mm
• April 1 SWE is projected to decrease by an
average of approximately 28-29% across the
state by the 2020s, 38-46% by the 2040s and
56-70% by the 2080s, based on the composite
scenarios averaging the effects of all climate
models
• By the 2080s, seasonal streamflow timing in
snowmelt dominant and transient rain-snow
mixed watersheds will shift significantly
• Annual runoff across the state is projected to
increase by 0-2% by the 2020s, 2-3% by the
2040s, and 4-6% by the 2080s and these
changes are mainly driven by projected
increases in winter precipitation
Figure 3.2: Mean 1916-2006 (top right panels), projected 2020s, 2040s
and 2080s simulated April 1 SWE in milimeters, using two emissions
scenarios A1B (left) and B1 (right). 2.5cm is approximately equal to one
inch.
Energy
Forests
Coasts
21st Century Climate Projections
50”
• Sea Level Rise (SLR) will shift the coastal
beaches and increase erosion of
unstable bluffs, endangering houses
and other structures built near the
shore or near the bluff edges.
40”
30”
• Shellfish may be negatively impacted by
increasing ocean temperatures and
acidity, due to shifts in disease and
growth patterns, and to more frequent
harmful algal blooms (HABs).
20”
13”
10”
6”
3”
6”
2050
2100
Figure 3.4: Projected sea level rise in Washington’s
waters relative to 1980-99, in inches. Shading
roughly indicates likelihood.
• These conclusions extend to the
numerous ports and marinas in the
Puget Sound region, which must
accommodate to SLR or retreat to
higher ground if they are to continue to
function as major transshipping points
for US-Asia trade. .
Agriculture
• Yields of dryland
winter wheat are
projected to increase
slightly from climate
change alone for the
2020s, and 15-30%
with elevated CO2 as
the century
progresses.
• Yields of irrigated
potatoes are
projected to decline
8% from climate
change alone for the
2020s and 22% for
the 2080s, but rising
CO2 would cut these
declines to only 2%
and 3% respectively.
Figure 3.7 Change is areas of potential poine
species ranges
• The area burned by fire
regionally is projected to
increase 200-300%
(scenario A1B).
• Mountain pine beetle poses a significant threat to Washington’s pine
forests.
• Tree species composition will change as species respond uniquely to a
changing climate.
• The area of severely water-limited forests will increase by 32% in the
2020s, and an additional 12% in both the 2040s and 2080s.
Infrastructure
• Stormwater impacts and
management already
carry significant
economic costs for
municipalities throughout
western WA, as well as
the rest of the state.
• The potential for changes
in precipitation intensity
would increase these
costs.
Figure 3.8 Comparison of 25 year 24 hour design storms
based on observed and modeled data at SeaTac airport
Human Health
Figure 3.5: Generalized agricultural land use map for the State of Washington
• Apples and cherries are projected to be negatively
affected by climate change for the 2020s scenario,
with yield reductions of 3% and 20%, respectively
even with the effects of higher CO2
Salmon
• Washington State residents
are currently more likely to
die during heat events than
during more temperate
periods; risks increase during
heat waves lasting 2 or more
days, and are greatest for
older adults.
• Climate change in
Washington State is likely to
lead to significantly more
heat-related deaths
throughout this century.
Figure 3.9 Mortality relative risks for all non-traumatic causes
by heat event duration (99th percentile), Greater Seattle
area, 1980-2006.
• Although better control of air
pollution has led to improvements in air
quality, warmer temperatures threaten
some of the sizeable gains that have
been made in recent years.
Additional Information
More information on the Climate Impacts Group or
WA State Climate Impacts Assessment:
IPCC Fourth Assessment Report (AR4) daily climate projections for the 21st Century
(at roughly 100-300 km spatial resolution) are downscaled using two different
approaches: an empirical method and a regional climate model. The Pacific
Northwest domain, bounded by latitudes 41.5° and 49.5°N and longitudes 111° and
124°W, is used for downscaling. Downscaled climate scenarios are input to one of
two hydrologic models which calculate the water balance for the ensemble of
projections. Sector groups utilize climate and hydrologic predictions to assess
statewide impacts. We evaluate regional climate change impacts with focus on
Washington State, which includes the lower Columbia River basin, as well as coastal
drainages, including the Puget Sound basin
Figure 3.3. Effects on A) heating energy demand and B) cooling
energy demand for several combined scenarios of population and
climate averaged over WA state. Panel C) shows monthly
averages of simulated system-wide energy production from the
Columbia River hydro system for 20th century climate, compared
to future scenarios for the 2020s, 2040s, and 2080s for the A1B
emissions scenario.
Conside ring both popu lation and climate warming scena rios, heating demand is
projected to rise to values about 30% highe r than late-20th century values by the
2040s.
Energy demand for cooling is projected to increase by a factor of 3.2-3.9 by the
2040s, and by a factor of 4.4 - 8.5 by the 2080s.
The Climate Impacts Group
www.cses.washington.ed/cig
Figure 3.6: August mean surface air temperature and maximum stream temperature for 1970-1999 (left) and
the 2040s (right, emission scenario A1B)
• In the 1980s, the majority of stations in the interior Columbia Basin are
classificed as stressful (annual maximum weekly temperature >15.5°C.
• The duration of temperatures causing thermal migration barriers and
extreme thermal stress are predict quadruple by the 2080s.
Marketa McGuire Elsner
[email protected]
These results will be release in February 2009 in our final report.
The Washington State Climate Change Impacts Assessment: Evaluating Washington’s Future in a Changing
Climate
Results will also be released at an all day conference on Febraury 12, 2009. Additional information may be
found at:
http://cses.washington.edu/cig/outreach/waccia/index.html