SEATTLE – A climate researcher at the University of Washington says Pacific Northwest winters will be getting more gray and rainy over the next 50 to 100 years, due to a low-pressure system near the Aleutian Islands that is moving farther to the north and east.
Eric Salathe said weather that far in the future may not seem relevant to the average person, but the storms brought on by climate change will affect everyone paying for or designing a new bridge or roadway today.
Weather systems near the Aleutian Islands affect rain patterns in western Oregon, Washington, British Columbia and Alaska because the path of storms along the jetstream is affected by what happens in and above the Pacific Ocean, Salathe explained.
"The whole storm system in the north Pacific is tracking northward," but that's just half of the story, Salathe said. "Even though the storms are moving northward, they are becoming more intense."
He predicted a 5 percent to 15 percent increase in Washington and Oregon rain and a 10 percent to 20 percent increase in Alaska rain 50 to 100 years from now. The storms will be both more intense and more frequent, leading to more flooding, more water flow in rivers and erosion of salmon habitat.
"The problem is it's more water, but more water at the wrong time. We already have plenty of water in November," Salathe said.
When asked if this forecast could be good news for skiers, the researcher said it probably wouldn't be helpful to anyone but engineers and planners. Lower-elevation ski areas could see more rain than snow in future seasons because of a combination of global warming and increased precipitation, he said.
People who design infrastructures like bridges and stormwater systems with underground pipes or culverts depend on information like Salathe's report, which was published Oct. 13 in the online edition of the journal Geophysical Research Letters.
"Often they plan these things based on what we've seen in the recent past. The future isn't going to look like the past," Salathe said. "The best thing is to factor in a little bit more margin of safety."
Salathe said computer technology improvements in the last five years have made this kind of precise climate predicting possible. His team of researchers, part of the university's Joint Institute for the Study of the Atmosphere and Oceans, took data gathered by other scientists around the world and analyzed it for the Pacific Northwest. The study was paid for by the National Oceanic and Atmospheric Administration.
He said the Pacific Northwest's climate could eventually be modified if people act to halt or slow global warming and climate change, but previous policies and actions have already decided what will happen in the next 50 years.
"If we stabilized emissions, these scenarios have much less of an impact on the later half of the century," Salathe said, suggesting people drive less, use more efficient vehicles and influence developing economies like China to be more energy efficient than the United States has been. "The worst parts are still up to us."