A long-term warming trend threatens the region's water supply, fish and other issues, scientists warn - Miles at U of Washington
- Climate experts forecast trouble
A long-term warming trend threatens the region's water supply, fish and
other issues, scientists warn
RICHARD L. HILL
SEATTLE -- Multiyear droughts and more winter precipitation in the form
of rain rather than snow could become commonplace in the Northwest,
climate scientists said Friday
New studies indicate that the Cascades are in trouble if climate
projections for the coming decades are accurate, said Edward
Miles, leader of the Climate Impacts Group at the University of
Northwest temperatures will increase by about 3 to 6 degrees Fahrenheit
by the 2040s, and the Cascades snowpack will decline by 59 percent by
2050, Miles said.
The gloomy scenario portends significant problems for the Northwest's
hydropower, fish, irrigation and reservoirs.
"If you think about this in terms of risk management, it's past time to
buy some insurance," Miles said in reporting the findings at the annual
meeting of the American Association for the Advancement of Science. "And
the insurance is planning. It takes 20 years to change a water supply
system, so time's a-wastin'."
Miles said the study by his group, the Scripps Institution of
Oceanography and the Pacific Northwest National Laboratory updated their
earlier projections, published a year ago in the journal Climatic
Change. The study showed that future conditions could be even worse than
scientists first thought.
"These results are more dramatic than past results because we have more
improved models that include much greater climate detail," Miles said in
He also reported on a UW study completed last week with scientists from
the University of Colorado that examined 800 snowpack records from 1950
to 2000 for the entire West, from southern Arizona to central British
Columbia and from the coastal mountain ranges to the Rockies.
Although he declined to give details because the findings have not been
published yet in a scientific journal, Miles said both the computer
models and the direct observations tell the same story about the past
half-century: About 75 percent of the West has seen declines in spring
snowpack in excess of 30 percent in low to middle elevations. He added
that the Cascades have been particularly hard-hit, along with mountain
ranges in Northern California.
Philip Mote, research scientist with the UW Climate Impacts Group, and
Martin Clark of the University of Colorado found in their study that the
Cascades' average April 1 snowpack had decreased by 60 percent between
1950 and 2000. "I was expecting to see only a zero to 30 percent
decline, so I was surprised by the results," Mote said in an interview.
They also found that average temperatures had increased by between 2.5
and 3.5 degrees Fahrenheit at many sites throughout Oregon and
Washington since 1920.
"What these observations emphasize in surprising detail is that the
projections for the future are already coming true," said Mote, who is
the Washington state climatologist. "It's not just saying that 50 years
out that these things are going to happen; we're already on that path
and farther along it than we knew."
Mote said that the largest snowpack declines in the West are projected
to be in the Cascades, and the new study shows that the greatest losses
in the West during the past 50 years have been in the Cascades.
Miles and his colleagues attribute the snowpack losses primarily to
temperature increases. The Northwest has had a 1.5 degree increase in
average annual temperature in the past century, nearly a half-degree
more than the global temperature increase.
In addition to foreseeing less snowpack, the scientists project that
summer drought seasons will lengthen by about a month to six weeks.
"Spring flow peaks will come earlier and won't be as large," Miles said,
which will put more demands on water use from the Columbia and other
Another Northwest scientist, L. Ruby Leung, a staff scientist at the
Pacific Northwest Laboratory in Richland, Wash., reports in the current
issue of the journal Climatic Change that global warming will diminish
the amount of water stored in snow in the West's coastal mountains by as
much as 70 percent in the next 50 years. Her study suggests that the
decrease in snow cover from the Cascades to California's Sierra Nevada
range will lead to increased fall and winter flooding and prolonged
spring and summer drought.
Leung said with more winter precipitation falling as rain instead of
snow -- two-tenths of an inch to more than half an inch of rain a day --
that would push the snow line up from 3,000 feet to 4,000 feet. She will
describe her study's findings Monday to the 5,000 scientists attending
the Seattle meeting.
--------- Forwarded message ----------
From: Robert T Maginnis
To: Debate <Debate@...>
Date: Sat, 14 Feb 2004 18:17:35 -0800
Subject: warming trend threatens the region's water supply, fish
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