A new U.S. Geological Survey (USGS) study paints an ominous picture of the nation’s western forests, finding that the mortality rate for trees has doubled over the last several decades because of rising temperatures and dwindling water supplies tied to global warming.
Researchers from the USGS, the U.S. Forest Service (USFS) and six universities, including the University of Colorado, Boulder, examined historical data from 76 different forested areas in three regions across the West and found that mortality rates were rising across the board due to climate change.
The study was first published last week by Science magazine.
One of the study’s authors, University of Colorado geography professor Thomas T. Veblen, put the findings in perspective for Colorado residents in a Washington Post article last week:
Veblen said the combination of increased wildfires, drought and bark beetles has devastated some of his state’s forests. Temperatures in Colorado’s sub-alpine forests, which are between 8,500 and 10,000 feet in altitude, have risen markedly over the past 50 years during all seasons, he said.
Mountain pine bark beetles have killed roughly 3.5 million acres of lodgepole pine forests in northwestern Colorado over the past decade, wiping out 90 percent of pine forests in that area, Veblen said. During the same time period, spruce bark beetles also killed large areas of spruce forest in northern and southwestern Colorado.
“Our society needs to devise policies that will help us to adapt to the changes that are under way,’” Veblen said. “This is further evidence that we’re seeing continued effects of the warming in increased fire risk.”
Perhaps the most frightening conclusion of the new study is that if current warming trends continue, western forests will move from absorbing carbon and removing greenhouse gases from the atmosphere to emitting more carbon dioxide than they can absorb.