Climate Change Impacts in the Pacific Northwest

Climate Science in the Public Interest

Paul Hezel Dept of Atmospheric SciencesUW Program on Climate Change (PCC)

Special thanks to: Lara Whitely BinderClimate Impacts GroupUniversity of Washington

Take Home Messages

• Global and regional climate is changing and the human influence has emerged from the “noise”

• These changes are expected to accelerate in the coming decades

• Changes in snowpack and streamflow caused by rising temperatures will have important consequences for resources across the PNW

• Local, State and Regional Initiatives are starting to address mitigation and adaptation (but there’s a lot of work to do…)

Greenhouse gases (water vapor, CO2, CH4, N2O) play a

critical role in determining global temperature

Rapid increases in greenhouse gases are changing this natural balance

Arctic Sea Ice Minimums

2007 2008

How different were 2007/2008?

2007 2008

How different were 2007/2008?

2007 2008

Average global temperature increase

Warming since the 1950s very likely (>90% chance) due to human increases in GHG. (IPCC AR4)

Temperature on longer time scales

Annual Average CO2 ConcentrationMauna Loa, HI (Elevation: 12,000 ft.)

310

320

330

340

350

360

370

380

1955 1965 1975 1985 1995 2005

Year

Co

nce

ntr

atio

n (

pp

m)

CDIAC, US Department of Energy

+35%

Figure source: IPCC 2007

How do we know it’s greenhouse gases?

Require GHG forcing to explain observed temperature rise

(with GHG)

(without GHG)IPCC 2007

Growth Rates (per year)

Global Climate Change…

• Climate is changing

• Human activity is responsible– Greenhouse gases warm the planet– We are increasing the greenhouse gas

concentration

• Have these atmospheric concentrations been higher? Yes, but not in at least 640,000 years (and for CO2, likely not for ~4 million years)

• Current social, economic, and cultural systems based on a steady climate with known variability

… and therein lie the challenges

So where are we heading?

Global Climate Change…

NOW

Projected CO2 Concentrations

Scenarios

Projected warming

IPCC “best estimate” range of global-scale warming by the 2090s:

3.2°F-7.2°F

Warming in the next few decades largely driven by current and near-term atmospheric GHG concentrations

Projected 21st century Global Warming

Risks of future climate change

Source: IPCC 2001

Possible Threats and Global impacts…

• Increase of extreme weather events• Sea level rise / Flooding of coastal communities • Ocean acidification• ‘Wet gets wetter, dry gets drier’• Loss of polar ice caps (esp Arctic) • Feedbacks within the climate system can amplify

changes• Ecosystem change• Spread of diseases

What climate signals are observed in PNW?

• Temperatures

• Glaciers/Snowpack

• Streamflow

• Frost days

Signal is complicated by natural climate oscillations. ENSO/PDO.

Nearly every glacier in the Cascades and Olympics has retreated during the past 50-150 years

Photos courtesy of Dr. Ed Josberger, USGS Glacier Group, Tacoma, WA

South Cascade Glacier, 1928 (top) and 2000 (right)

Average annual temperature increased +1.5F in the PNW during the 20th century

3.6 °F

2.7 °F

1.8 °F

0.9 °F

Cooler Warmer

Mote 2003(a), updated

Temperature Trends (°F per century), since 1920

April 1 snowpack has decreased throughout the PNW with losses of 30-60% at many individual stations (1950-2000)

Decrease Increase

Similar snowpack declines are seen throughout the western United States

Decrease Increase

Key Trends in PNW Climate

Trends in Spring Runoff

Stewart et al. 2005 Stewart I.T., Cayan D.R., Dettinger M.D., 2005: Changes toward earlier streamflow timing across western North America, Journal of Climate, 18(8):1136-1155.

Peak of spring runoff is moving earlier into the spring throughout western U.S. and Canada

Fewer Frost Days in the Late 20th Century

Largest trends observed in the PNW; most of the trend driven by decline in spring frost days G. A. Meehl, C.Tebaldi and D. Nychka (2004) Changes in frost days in simulations of 21st century climate. Climate Dynamics, Vol. 23, No. 5, pp. 495-511

• Are these changes due entirely to climate change?

NO, modes of natural variability have a role in these trends (e.g., El Niño, PDO)

• Are these changes due entirely to natural climate variability?

NO, natural variability cannot explain all of the trends

…a climate change signal appears to be emerging

Attribution

Changes to come…

UW Climate Impacts Group

Projected Increases in PNW Temp

Changes relative to 1970-1999

7.2°F

3.6°F

0°F

10.8°F

14.4°F

+2.2ºF (1.1-3.4ºF)

+3.5ºF (1.6-5.2ºF)

+5.9ºF (2.8-9.7ºF)

°C

• Rate of change expected to be 3x greater

• Warming expected in all seasons, greatest in summer

• Rate of change expected to be 3x greater

• Warming expected in all seasons, greatest in summer

 

Modest Changes in PNW Precipitation

Note: there is high confidence in projected temp changes,

less in precipitation changes

Modest increases (1-2%) in annual average precipitation

Most of the increase comes in the winter months (but in what intensity?)

Projected increase in average does not exceed 20th century variability

Spring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basins

Snowpack will melt earlier with warmer spring temperatures

Lower Spring Snowpack

+4°F, +4.5% winter precip

April 1 Snowpack

~2050s to 2080s

Streamflow Impacts

Higher winter streamflowsEarlier and lower peak runoff (mid/high basins)

Lower late spring streamflowLower, warmer summer streamflow

Projected streamflow changes in the Quinalt and Yakima Rivers

+3.6 (~2050s) to +5.4°F (~2080s)

~2050s to 2080s

Cascading impacts …

UW Climate Impacts Group

Impacts to Many Local Concerns

Snow-dependent Water Supply

Sea Level Rise

Food production/Ag Economies

Forests/Timber Economies

Flood Risk

Instream Flows

Energy Supply

Water QualityPublic Health

Changing Risk for Today’s Problems

Risk of drought increases…

With 3.6°F warming, 50-year droughts become 10-year droughts and 10-year droughts become 2.2-year droughts (Scott et al. 2006)

Risk of flooding changes….

General increase in risk of winter flooding and combined sewer overflows in low- and mid-elevation basins

Lower risk of spring flooding in snowmelt basins due to lower spring snowpack

Early peak flows

Floods

??

Warm, lowstreamflow

Salmon Impacted Across Full Life-Cycle

Sea Level Rise (SLR) in the PNW

• Thermal expansion of the global ocean;

• Melting of land-based ice;

• Atmospheric dynamics, particularly changes in wind which push coastal waters toward or away from shore;

• Local tectonic processes (subsidence and uplift)

Coasts

• Medium estimates of SLR for 2100:

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

• Higher estimates (up to 4 feet in Puget Sound) cannot be ruled out.

Rising sea levels will increase the risk of flooding, erosion, and habitat loss along much of Washington’s 2,500 miles of coastline.

3”6”

30”

50”

2050 2100

13”

40”

20”

10”6”

Inundation Levels in Olympia from Current and Projected Changes in High Tides

A. Tidal datum elevation 18 feet B. Tidal datum elevation 19 feet

C. Tidal datum elevation 20 feet D. Tidal datum elevation 22 feet

• Human HealthIncreased thermal stress from extreme heat events, decreased air quality (ozone; particulate matter), changes in range of/habitat for/exposure to disease vectors likely

• RecreationShortened winter ski season (but improved access?), impacts in summer from forest fires

• HydropowerIncreased winter streamflows benefit winter hydropower production; greater tradeoffs between hydropower, instream flows, irrigation, and recreation

Other Projected Regional Impacts

• ForestsIncreased risk of wildfire, vulnerability to insects, decreased growth & regeneration

• Agriculture Decreased irrigation supply, increased heat stress/insects, increased growing season

• InfrastructureThe potential for more intense winter precipitation would increase the already high costs of stormwater management.

Other Projected Regional Impacts

Responding to Climate Change: Mitigation and Adaptation

Mitigation activities

Reducing emissions of greenhouse gases

Adaptation activities

Reducing the impacts of climate change as mitigation strategies are debated and enacted.

1.6

Billions of Tons Carbon Emitted per Year

Current p

ath =

“ram

p”

Historical emissions Flat path

0

8

16

1950 2000 2050 2100

Stabilization Wedges

16 GtC/y

Eight “wedges”

Goal: In 50 years, sameglobal emissions as today

Energy Efficiency & Conservation

CO2 Capture & Storage

Stabilization Triangle

Renewable Fuels& Electricity

Forest and Soil Storage

Fuel Switching

What are the wedge strategies?

Nuclear Fission

2007 2057

8 GtC/y

16 GtC/y

TriangleStabilization

Carbon Mitigation Institute, Princeton University

Regional Climate Initiatives • Over half of US may

be covered by a regional GHG cap-and-trade system in 1-2 years

• Strong desire by stakeholders and policy makers to reflect regional concerns

• RGGI has already influenced draft national legislation, e.g. increasing inclination to auction permits

Source: Pew Center for Climate Change, www.pewclimate.org

Climate Action In Washington State

• Western Climate Initiative• WGA Clean and Diversified Energy Initiative• West Coast Governor's Global Warming Initiative• Washington Climate Plan• Washington Commissions and Advisory Groups• Washington Emissions Target• Washington Power Plant Cap or Offsets• Washington RPS (Renewable Portfolio Standards)• Washington to Adopt CA Vehicle Standards• Washington Appliance Standards• Washington Biofuel Standard• Washington EERS

Western Climate Initiative

• Regional Goal set in August 2007– 15% below 2005 levels by 2020– “do their share” to reduce global– emissions between 50% and 85% by 2050

• September, 2008, announced regional

cap-and-trade plan recommendations– Phase 1 by 2012; Phase 2 by 2015

• Currently includes 7 states, 4 provinces, with another 6 states, 1 province and 6 Mexican states observing

• New entrants must have:– an equally stringent economy-wide GHG reduction goal– a comprehensive multi-sector climate action plan to achieve the goal– committed to adopt GHG tailpipe standards for passenger vehicles

Renewable Portfolio Standards

Local Actions… • Over 884 municipalities

have signed US Mayors Climate Agreement (representing 81 million people)– GHG emissions 7% below

1990 by 2012

• Like states, cities/mayors – are adopting detailed action

plans• focus on green buildings,

low-carbon electricity supply, transportation alternatives, building energy efficiency

– testifying in Congress– influencing regional policy

(e.g. Texas coal plants)– are, like governors, in a race

to the top

King County - Ron Sims' Global Warming Initiative

• Concrete action in county gov’t and agencies

The wedge approach...

Originally published October 24, 2008 at 12:00 AM | Page modified October 24, 2008 at 10:53 AM

Guest columnist

Solving the financial crisis by averting the climate crisis

Despite the Wall Street meltdown and ongoing financial crisis, the next U.S. president must address the challenges of climate change and energy security. Investment in energy alternatives will help draw the nation out of financial doldrums.

By Chip Giller and David Roberts

Special to The Times

Originally published October 20, 2008 at 12:00 AM | Page modified October 20, 2008 at 10:58 AM

Neal Peirce / Syndicated columnist

States, cities step up climate-change responses

To meet the climate-change challenge, thousands of low-carbon strategies need to be fashioned from America's grass roots. Seattle and King County get it.

By Neal Peirce

Syndicated Columnist

Summary

• Global and regional climate is changing and the human influence has emerged from the “noise”

• These changes are expected to accelerate in the coming decades. (Increasing rates of change)

• Regional signals are clearer in Pacific Northwest. Significant regional impacts are expected.

• Local, State and Regional Initiatives are starting to address mitigation and adaptation (but there’s a lot of work to do…). Wedge approach is useful.

UW Program on Climate Changewww.uwpcc.washington.edu

Paul Hezel phezel@atmos.washington.edu

Thanks to Lara Whitely Binder and for More Info on Local and Regional Impacts of Climate

Change

The Climate Impacts Group

www.cses.washington.edu/cig

1

Average Annual System Wide Snow Storage

0

10

20

30

40

50

60

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

KA

F

Historic EnsembleGCM Ensemble 2000

GCM Ensemble 2020GCM Ensemble 2040

Impacts of Climate Change

Snowpack Average

annual maximum seen to decrease by as much as 50% by 2040

Timing of peak shifts earlier in year.

Extreme events will become more common.

Impacts of Climate Change on Supplies

1

Probability of Maximum Snow Pack in the Specific Month

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Pro

bab

ilit

y

Historic EnsembleGCM Ensemble 2000

GCM Ensemble 2020GCM Ensemble 2040

Impacts of Climate Change

Snowpack Average

annual maximum seen to decrease by as much as 50% by 2040

Timing of peak shifts earlier in year.

Extreme events will become more common.

Impacts of Climate Change on Supplies

1

Likelihood of April System Snowpack Storage

0

20

40

60

80

100

120

140

160

180

0 0.2 0.4 0.6 0.8 1

non-exceedance probability

KAF

Historic Ensemble

GCM Ensemble 2000

GCM Ensemble 2020

GCM Ensemble 2040

Impacts of Climate Change

Snowpack Average

annual maximum seen to decrease by as much as 50% by 2040

Timing of peak shifts earlier in year.

Extreme events will become more common.

Impacts of Climate Change on Supplies

Blue line is 10-year running mean; Green bar is 2006 (provisional value)