Download Slide 1

Hydrologic Implications of Climate
Change for the Western U.S., Pacific
Northwest, and Washington State
Alan F. Hamlet
•JISAO/CSES Climate Impacts Group
•Dept. of Civil and Environmental Engineering
University of Washington
Recession of the Muir Glacier
Aug, 13, 1941
Aug, 31, 2004
Image Credit: National Snow and Ice Data Center, W. O. Field, B. F. Molnia
http://nsidc.org/data/glacier_photo/special_high_res.html
Global Climate Change Scenarios
for the PNW
Consensus Forecasts of Temperature and Precipitation Changes from IPCC AR4 GCMs
21st Century Climate Impacts for the Pacific Northwest Region
Mote, P.W. and E. P. Salathe Jr., 2009: Future climate in the Pacific Northwest (in review)
PDO
Effects of the PDO and ENSO on Columbia River
Summer Streamflows
450000
Cool
Cool
350000
300000
250000
200000
Red=warm ENSO Green=ENSO neutral Blue=cool ENSO
2000
1990
1980
1970
1960
1950
1940
1930
1920
1910
150000
1900
Apr-Sept Flow (cfs)
Warm
Warm
400000
Snowpack
Schematic of VIC Hydrologic Model and
Energy Balance Snow Model
Snow Model
Trends in April 1 SWE 1950-1997
Mote P.W.,Hamlet A.F., Clark M.P., Lettenmaier D.P., 2005, Declining mountain snowpack in western
North America, BAMS, 86 (1): 39-49
DJF avg T (C)
Overall Trends in April 1 SWE from 1947-2003
Trend %/yr
Trend %/yr
Hamlet, A.F., Mote, P.W, Clark, M.P., Lettenmaier, D.P., 2005: Effects of temperature and precipitation
variability on snowpack trends in the western U.S., J. of Climate, 18 (21): 4545-4561
DJF avg T (C)
Temperature Related Trends in April 1 SWE from 1947-2003
Trend %/yr
Trend %/yr
Hamlet, A.F., Mote, P.W, Clark, M.P., Lettenmaier, D.P., 2005: Effects of temperature and precipitation
variability on snowpack trends in the western U.S., J. of Climate, 18 (21): 4545-4561
DJF avg T (C)
Precipitation Related Trends in April 1 SWE from 1947-2003
Trend %/yr
Trend %/yr
Hamlet, A.F., Mote, P.W, Clark, M.P., Lettenmaier, D.P., 2005: Effects of temperature and precipitation
variability on snowpack trends in the western U.S., J. of Climate, 18 (21): 4545-4561
Plotting Areas of High Hydrologic Disturbance
Elsner et al., 2009: Implications of 21st Century climate change for the
hydrology of Washington State (in review)
Change in Long-Term Mean April 1 SWE in WA
-29%
-27%
-44%
-37%
-65%
-53%
Elsner et al., 2009: Implications of 21st Century climate change for the
hydrology of Washington State (in review)
Changes in Seasonal
Streamflow Timing
Simulated Changes in Natural Runoff Timing in the Naches
River Basin Associated with 2 C Warming
120
Simulated Basin Avg Runoff (mm)
100
80
Impacts:
•Increased winter flow
•Earlier and reduced peak flows
•Reduced summer flow volume
•Reduced late summer low flow
1950
60
plus2c
40
20
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
Projected Streamflow Timing
Shifts in Washington
Historical and Projected 21st Century Flows for the A1b Scenario
6000
historical
Simulated Natural Flows (cfs)
2020A1b
5000
2040A1b
2080A1b
4000
3000
2000
1000
Chehalis River
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
Historical and Projected 21st Century Flows for the A1b Scenario
6000
Simulated Natural Flows (cfs)
historical
2020A1b
5000
2040A1b
2080A1b
4000
3000
2000
1000
Quinault River
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
Historical and Projected 21st Century Flows for the A1b Scenario
3500
Simulated Natural Flows (cfs)
historical
2020A1b
3000
2040A1b
2080A1b
2500
2000
1500
1000
500
Elwah River
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
Historical and Projected 21st Century Flows for the A1b Scenario
35000
Simulated Natural Flows (cfs)
historical
2020A1b
30000
2040A1b
2080A1b
25000
20000
15000
10000
5000
Skagit River
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
Historical and Projected 21st Century Flows for the A1b Scenario
12000
Simulated Natural Flows (cfs)
historical
2020A1b
10000
2040A1b
2080A1b
8000
6000
4000
2000
Yakima River
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
Climate Change Will Result in Widespread Transformation of
Snowmelt and Transient Watersheds to Rain Dominant
Watersheds
Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key
aspects of freshwater salmon habitat in Washington State, (in review)
Changes in Hydrologic Extremes
Regionally Averaged Temperature Trends Over the Western U.S. 1916-2003
3.00
PNW
Linear Trend (Deg. C per century)
CA
PNW
1.50
1.00
0.50
0.00
-0.50
-1.00
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
4.00
Linear Trend (Deg. C per century)
CA CRB
GBAS
2.00
oct
GB
CRB
Tmax
2.50
CA
3.50
CRB
Tmin
GBAS
3.00
PNW
2.50
2.00
1.50
1.00
0.50
0.00
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
DJF Avg Temp (C)
Simulated Changes in the 20-year Flood
Associated with 20th Century Warming
DJF Avg Temp (C)
X20 2003 / X20 1915
X20 2003 / X20 1915
X20 2003 / X20 1915
Summary of Flooding Impacts
Rain Dominant Basins:
Possible increases in flooding due to increased precipitation
intensity, but no significant change from warming alone.
Mixed Rain and Snow Basins Along the Coast:
Strong increases due to warming and increased precipitation
intensity (both effects increase flood risk)
Inland Snowmelt Dominant Basins:
Relatively small overall changes because effects of warming
(decreased risks) and increased precipitation intensity
(increased risks) are in the opposite directions.
Future Projections of Flood Risk in Washington
•Floods in western WA are
expected to increase in
magnitude due to the combined
effects of warming and
increasingly intense winter
storms.
•In other parts of the State,
changes in flooding are smaller,
and in eastern WA projected
reductions in flood risk are
common due to loss of spring
snow cover.
Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key
aspects of freshwater salmon habitat in Washington State, (in review)
Changes in Low Flow Risks
7Q10 values are
projected to
systematically decline
in western WA due to
loss of snowpack and
projected dryer
summers
Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key
aspects of freshwater salmon habitat in Washington State, (in review)
Landscape Scale Disturbance
Annual area (ha × 106) affected by MPB in BC
9.0
2005
Bark Beetle Outbreak in British Columbia
8.0
2004
7.0
6.0
5.0
2003
4.0
3.0
2.0
2002
1.0
2001
2000
1999
0
1910 1930 1950 1970 1990 2010
Year
(Figure courtesy Allen Carroll)
Wide-Spread Glacial Retreat has Accompanied 20th
Century Warming.
1902
2002
The recession of the Illecillewaet Glacier at Rogers Pass between 1902
and 2002.
Photographs courtesy of the Whyte Museum of the Canadian Rockies & Dr.
Henry Vaux.
Loss of glacial mass may increase
summer flow in the short term and
decrease summer flow in the long term.
Warming Air Temperatures will Increase Water Temperature
Mantua, N., I. Tohver, A.F. Hamlet, 2009: Impacts of climate change on key
aspects of freshwater salmon habitat in Washington State, (in review)
Adaptation
Approaches to Adaptation and Planning
•Anticipate changes. Accept that the future climate will be
substantially different than the past.
•Use scenario based planning to evaluate options rather
than the historic record.
•Expect surprises and plan for flexibility and robustness in
the face of uncertain changes rather than counting on one
approach.
•Plan for the long haul. Where possible, make adaptive
responses and agreements “self tending” to avoid repetitive
costs of intervention as impacts increase over time.