Tree rings record changing snowpack, research finds

Greg Pederson sees the recent publication of his research on snowpack declines in the West as a prime opportunity to reiterate the difference between climate and weather in this record-setting wet spring. Pederson, an ecologist with the U.S. Geological Survey in Bozeman, was the lead author of a paper published last week in Science magazine detailing the decline in snowpack observed by examining tree rings from the watersheds of the Columbia, Missouri and Colorado river basins dating back more than 800 years. His findings: Not only has snowpack declined compared to past climate fluctuations, but there's also been a "decoupling" of precipitation in the Colorado River basin and that of the Northern Rockies. What this means is the tendency for the north to have high snowpacks when the south is experiencing meager ones, and vice versa, has shifted to declining snowpack across the West. The long-term implications of reduced snowpack in the West, which provides water to an estimated 70 million people in just the three drainages Pederson studied, portends huge challenges for water managers in the future, he said...more