Public Release: 12-Dec-2016
Mountain glaciers are showing some of the strongest responses to climate change
University of Washington
Mountain glaciers have long been a favorite poster child of climate change. The near-global retreat of glaciers of the last century provides some of the most iconic imagery for communicating the reality of human-driven climate change.
But the scientific basis for their retreat has been less clear. Glaciers respond slowly to any climate changes, they are susceptible to year-to-year variations in mountain weather, and some of the largest are still catching up after the end of the Little Ice Age. Scientists can connect climate change to the overall retreat of glaciers worldwide, but linking an individual glacier's retreat to climate change has remained a subject of debate.
The last report from the Intergovernmental Panel on Climate Change concluded only that it was "likely" that a "substantial" part of mountain glacier retreat is due to human-induced climate change -- a much weaker conclusion than for temperature and other things.
Now, using statistical techniques to analyze 37 mountain glaciers around the world, a University of Washington study finds that for most of them the observed retreat is more than 99 percent likely due to climate change. In the climate report's wording, it is "virtually certain" that the retreat of these mountain glaciers is due to climate change over the past century.
"Because of their decades-long response times, we found that glaciers are actually among the purest signals of climate change," said Gerard Roe, a UW professor of Earth and space sciences. He is corresponding author of the study published Dec. 12 in Nature Geoscience, and presented this week at the American Geophysical Union's annual fall meeting in San Francisco.
"Even though the scientific analysis arguably hasn't always been there, it now turns out that it really is true -- we can look at these glaciers all around us that we see retreating, and see definitive evidence that the climate is changing," Roe said. "That's why people have noticed it. These glaciers are stunningly far away from where they would have been in a preindustrial climate."