Richard N.Palmer, Alan F. Hamlet,

1
Transboundary Implications of Climate Change for
the Columbia River Basin

• Richard N.Palmer, Alan F. Hamlet,
• Philip W. Mote, Nate Mantua,
• Dennis P. Lettenmaier
• JISAO/CSES Climate Impacts Group
• Dept. of Civil and Environmental Engineering
• University of Washington

2
Science of climate change

• Thousands of peer-reviewed scientific papers
• Intergovernmental Panel on Climate Change (IPCC)
• Major reports in 1990, 1996, 2001, 2007
• 2001 report involved 637 contributing authors,
  420 peer-reviews, then another review by
  government experts and policy-makers
• Conclusions
• An increasing body of observations gives a
  collective picture of a warming world and other
  changes in the climate system.
• There is new and stronger evidence that most of
  the warming observed over the last 50 years is
  attributable to human activities.

3
Science of climate change

• 2001 White House request for advice from the US
  National Academy of Sciences
• are there any substantive differences between
  the IPCC Reports and IPCC Summaries?
• National Research Council convened a panel of 11
  leading US climate scientists to write the report
• Conclusions
• Greenhouse gases are accumulating in Earths
  atmosphere as a result of human activities,
  causing temperatures to rise The committee
  generally agrees with the assessment of
  human-caused climate change presented in the IPCC
  scientific report

4
Example of a flawed water planning study The
Colorado River Compact of 1922
The Colorado River Compact of 1922 divided the
use of waters of the Colorado River System
between the Upper and Lower Colorado River Basin.
It apportioned in perpetuity to the Upper and
Lower Basin, respectively, the beneficial
consumptive use of 7.5 million acre feet (maf) of
water per annum. It also provided that the Upper
Basin will not cause the flow of the river at Lee
Ferry to be depleted below an aggregate of 7.5
maf for any period of ten consecutive years. The
Mexican Treaty of 1944 allotted to Mexico a
guaranteed annual quantity of 1.5 maf. These
amounts, when combined, exceed the river's
long-term average annual flow.       
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Whats the Problem?
Despite a general awareness of these issues in
the water planning community, there is growing
evidence that future climate variability will not
look like the past and that current planning
activities, which frequently use a limited
observed streamflow record to represent climate
variability, are in danger of repeating the same
kind of mistakes made more than 80 years ago in
forging the Colorado River Compact. Long-term
planning and specific agreements influenced by
this planning (such as long-term transboundary
agreements) should be informed by the best and
most complete climate information available, but
frequently they are not.
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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
7
As the West warms, spring flows rise and summer
flows drop Stewart IT, Cayan DR, Dettinger MD,
2005 Changes toward earlier streamflow timing
across western North America, J. Climate, 18 (8)
1136-1155
8
3.2C
C
1.7C
0.7C
1.2-5.5C
0.9-2.4C
Observed 20th century variability
0.4-1.0C
Pacific Northwest
9

-1 to 3
6
2
1
Observed 20th century variability
-2 to 21
-1 to 9
Pacific Northwest
10
Global Climate Change Scenarios and Hydrologic
Impacts for the PNW
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The warmest locations are most sensitive to
warming
2.3C, 4.5 winter precip
12
Changes in Simulated April 1 Snowpack for the
Canadian and U.S. portions of the Columbia River
basin ( change relative to current climate)
20th Century Climate
2020s (1.7 C)
2040s ( 2.25 C)
-3.6
-11.5
-21.4
-34.8
April 1 SWE (mm)
13
Naturalized Flow for Historic and Global Warming
Scenarios Compared to Effects of Regulation at
1990 Level Development
Historic Naturalized Flow
Estimated Range of Naturalized Flow With 2040s
Warming
Regulated Flow
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Water Resources Implications for the Columbia
River Basin
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Impacts on Columbia Basin hydropower supplies

• Winter and Spring increased generation
• Summer decreased generation
• Annual total production will depend primarily on
  annual precipitation

(2C, 6)
(2.3C, 5)
(2.9C, -4)
NWPCC (2005)
16
Warming climate impacts on electricity demand

• Reductions in winter heating demand
• Small increases in summer air conditioning demand
  in the warmest parts of the region

NWPCC 2005
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Adaptation to climate change will require complex
tradeoffs between ecosystem protection and
hydropower operations
Source Payne, J.T., A.W. Wood, A.F. Hamlet, R.N.
Palmer, and D.P. Lettenmaier, 2004, Mitigating
the effects of climate change on the water
resources of the Columbia River basin, Climatic
Change, Vol. 62, Issue 1-3, 233-256
18
Flood Control vs. Refill
Streamflow timing shifts can reduce the
reliability of reservoir refill
Full
Model experiments (see Payne et al. 2004) have
shown that moving spring flood evacuation two
weeks to one month earlier in the year helps
mitigate reductions in refill reliability
associated with streamflow timing shifts.
Payne, J.T., A.W. Wood, A.F. Hamlet, R.N. Palmer,
and D.P. Lettenmaier, 2004, Mitigating the
effects of climate change on the water resources
of the Columbia River basin, Climatic Change,
Vol. 62, Issue 1-3, 233-256
19
Temperature thresholds for coldwater fish in
freshwater

• Warming temperatures will increasingly stress
  coldwater fish in the warmest parts of our region
• A monthly average air temperature of 68ºF (20ºC)
  has been used as an upper limit for resident cold
  water fish habitat, and is known to stress
  Pacific salmon during periods of freshwater
  migration, spawning, and rearing

1.7 C
2.3 C
20
Implications for Transboundary Agreements in the
Columbia Basin

• Climate change will result in significant
  hydrologic changes in the Columbia River and its
  tributaries.
• Snowpack in the BC portion of the Columbia basin
  is much less sensitive to warming in comparison
  with portions of the basin in the U.S. and
  streamflow timing shifts will also be smaller in
  Canada.
• As warming progresses, Canada will have an
  increasing fraction of the snowpack contributing
  to summer streamflow volumes in the Columbia
  basin.
• These differing impacts in the two countries have
  the potential to unbalance the current
  coordination agreements, and will present serious
  challenges to meeting instream flows on the U.S.
  side.
• Changes in flood control, hydropower production,
  and instream flow augmentation will all be needed
  as the flow regime changes.

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Selected References and URLs Climate Impacts
Group Website http//www.cses.washington.edu/cig/
White Papers, Agenda, Presentations for CIG
2001 Climate Change Workshop http//jisao.washing
ton.edu/PNWimpacts/Workshops/Skamania2001/WP01_age
nda.htm Climate Change Streamflow Scenarios for
Water Planning Studies http//www.ce.washington.e
du/hamleaf/climate_change_streamflows/CR_cc.htm
Northwest Power and Conservation Council
Columbia Basin Hydropower Study http//www.nwppc.
org/energy/powerplan/plan/Default.htm Refs on
Climate Variability and Climate
Change http//www.ce.washington.edu/hamleaf/haml
et/publications.html