Effects of Climate Change on Hydrology and Food Production in the Pacific Northwest

Dr. Alan F. Hamlet

Climate science in the

public interest

Mote, P.W., and E.P. Salathé. 2010. Future climate in the Pacific Northwest. Climatic

Change 102(1-2): 29-50, doi: 10.1007/s10584-010-9848-z

Climate Change Scenarios

Figure shows change compared with 1970 - 1999 average

IPCC AR 4 Emissions Scenarios: A1B Medium High B1 Low

• Strong Warming: All Seasons,

Especially Summer

• Relatively Small Changes in

Annual Precipitation

• Wetter Falls, Winters, and

Springs

• Drier Summers

Model Consensus:

Hydrologic Modeling:

A “Translation” Between Climate Impacts and

Water Impacts

Snow Model

Schematic of VIC Hydrologic Model • Sophisticated, fully distributed,

physically based hydrologic model

• Widely used globally in climate change applications

• 1/16 Degree Resolution

(~5km x 7km or ~ 3mi x 4mi)

General Model Schematic

Hydrologic Impacts in the Skagit River Basin

Skagit River at Mount Vernon

Reductions in Snowpack

Changes in Magnitude and Seasonal Timing of StreamFlow

Hydrologic Extremes

Source: Lee & Hamlet, 2012

0

100,000

200,000

300,000

400,000

Unregulated CurFC AltFC

Q1

00

F

low

(cf

s)

2080s

100 year Flood

HistoricalHybrid delta _A1BAverage

+ 40%

0

100,000

200,000

300,000

400,000

Unregulated CurFC AltFC

Q1

00

F

low

(cf

s)

2040s

100 year Flood

HistoricalHybrid delta _A1BAverage

+ 23%

Skagit dams reduce flooding, but most of the runoff production during floods is

downstream of headwater dams, which limits the role that reservoir operations can

play in protecting the lower basin from projected larger future floods.

Changes in the Natural and Regulated 100-year Flood at Mt. Vernon

Changing Snow Line and Effective basin Area

Since 1958 the average winter freezing elevation is estimated

to have risen more than 600 feet in the Skagit basin. A higher

freezing elevation increases the effective basin area that

produces runoff during winter storms.

Changes in Regulated Low Flows (7Q10)

Low flows under natural conditions are substantially less than under

regulated conditions, but climate change reduces low flows in each case.

2040s 2080s

Impacts and Opportunities

Related to PNW Food

Production

Human Health

Agriculture/Economics

Salmon Forest Resources

Coasts Energy

Infrastructure

Water Resources

A comprehensive climate change impacts

assessment for Washington State

Adaptation

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

Simulated Changes in Eastern WA Crop Yields Due to the

Combined Effects of Dry Land Water Availability, Temperature,

and CO2 Enrichment

Crop 2020s 2040s 2080s

Dry Land Winter Wheat

+13 to +15%

+13 to +24%

+23 to +35%

Potatoes -2 to -3% -2 to -3% -2 to -3%

Apples* +6% +9% +16%

* Warmer conditions will likley require management

changes to maintain fruit quality.

Stöckle, C., R.L. Nelson, S. Higgins, J. Brunner, G. Grove, R. Boydston, M. Whiting,

and C. Kruger. 2010. Assessment of climate change impact on eastern Washington

agriculture. Climatic Change 102(1-2): 77-102, doi: 10.1007/s10584-010-9851-4.

In the Skagit basin, important crops such as

potatoes, spinach seed, raspberries, and

blueberries may be impacted by warmer

temperatures.

Lee, S-Y, A.F. Hamlet, 2011: Skagit Basin Climate Science Report, A

report prepared for Skagit County and the Envision Skagit Project,

(http://www.skagitcounty.net/Common/asp/default.asp?d=EnvisionSk

agit&c=General&P=reports.htm)

Impacts to Skagit Basin Crops

Reductions in Agricultural Water Supply

Impacts to Junior Water Rights Holders in the Yakima Basin

Vano, J.A., M. Scott, N. Voisin, C.O. Stöckle, A.F. Hamlet, K.E.B. Mickelson, M.M. Elsner, D.P. Lettenmaier, 2010:

Climate change impacts on water management and irrigated agriculture in the Yakima River basin, Washington,

USA, Climatic Change, DOI: 10.1007/s10584-010-9856-z

Loss of Viable Farmland in Vulnerable Floodplains and Coastal Areas

Historical 2040s 2080s

Effects of Projected Sea Level Rise and Increased Q100

on Inundation in the Skagit Lowlands

Source:

Hamman et al.

2012

Impacts to PNW Salmon

Mantua, N., I. Tohver, A.F. Hamlet, 2010: Climate change impacts on streamflow extremes and summertime

stream temperature and their possible consequences for freshwater salmon habitat in Washington State,

Climatic Change, online first, doi: 10.1007/s10584-010-9845-2