UW study examines decline of snowpack
Ed note: the headline is exactly opposite from the story and the truth. WA snowpack has NOT declined and this year set records for depth and snow-water-equivalence. Further, there has been no global warming for 10 years, despite dire predictions from the IPCC and Al Gore. The darn facts keep getting in the way of the political stampede.
By Warren Cornwall, Seattle Times, August 6, 2008 [here]
Despite previous studies suggesting a warmer climate is already taking a bite out of Washington’s snowpack, there’s no clear evidence that human-induced climate change has caused a drop in 20th century snow levels, according to a controversial new study by University of Washington scientists.
Maybe the snow in the Cascade Mountains isn’t in such immediate peril from global warming after all.
Despite previous studies suggesting a warmer climate is already taking a bite out of Washington’s snowpack, there’s no clear evidence that human-induced climate change has caused a drop in 20th century snow levels, according to a new study by University of Washington scientists.
In fact, the newest study also predicts the Cascade snows — vital to water supplies, crop irrigation and salmon — could enjoy a delay in the effects of global warming.
But the findings have already become part of a scientific debate with an unusually political tone. It’s an ongoing disagreement that has UW researchers taking sides against each other and has attracted the attention of political groups.
And a leading scientist on the other side of the debate said the latest analysis speculates about the future and offers little new about the past.
“They’re trying to forecast the next 20 years or so, and I don’t think they can do it,” said Alan Hamlet, a UW hydrologist who has written papers about historic Cascade Mountain snowpacks.
Past studies have frequently focused on steep declines in Cascade snowpack in the second half of the 20th century, with drops measuring 30 percent or more.
But Cliff Mass, a well-known UW meteorologist, said the new study, which he co-authored, shows it all depends on which years are examined. He and his co-authors argue snow levels were unusually high in the 1950s, creating a distorted picture of historic patterns.
Measurement of mountain snow levels were spotty before the 1950s, making it harder to get a complete picture. But Mass and his colleagues tried to estimate snowpack for earlier years based on measurement that did exist: the amount of water that flowed down streams as snow melted.
Using that method, they found a smaller drop in snowpack between the 1930s and today — 23 percent. That still may sound like a big drop, but the scientists argue that it could be statistically insignificant, so it’s hard to say whether it’s meaningful. They also say that many of the changes appear to be attributable to shifting weather patterns driven by the Pacific Ocean.
“We can’t see the global-warming signature in terms of a decline in snowpack,” said Mark Stoelinga, the study’s lead author, and a professor in the UW’s Atmospheric Sciences Department. … [more]