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The retreat of glaciers around the world has long been heralded as a definitive symbol of the effects of human activity on the global climate. However, due to a great deal of variability between glaciers, it’s been hard to actually pin that retreat on global climate change. Even the Intergovernmental Panel on Climate Change was only able to determine that it was “likely” a “substantial” cause of glacier retreat.
However, a team of researchers at the University of Washington has determined that glacier retreat over the last 130 years or so is almost certainly due to climate change. As in, more than 99 percent likely, with a 0.001 percent chance that the changes are natural, which works out to 1 in 100,000.
They’ve determined this by look at the history of recordings for 37 different glaciers in five geographic regions, which can be vastly different. Glaciers atop mountains in the deserts of Asia might get a mere 4 centimeters of ice in a year, while the South Cascade Glacier in the state of Washington can get as much as 3 meters. By looking at long-term measurements of each glacier on its own, they were able to determine that there has been more change in the last 130 years than at any time since the end of the last Ice Age.
“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 and see definitive evidence that the climate is changing,” says UW Earth and space sciences professor Gerard Roe, corresponding author of the paper. “That’s why people have noticed it. These glaciers are stunningly far away from where they would have been in a preindustrial climate.”
By taking the data for all these glaciers, they can tell that it’s a widespread issue and not related to one or two glaciers.
While this is good news because it verifies something we’ve long seen as a prime example of climate change, it’s obviously bad news because the world’s glaciers are retreating and it is because of human activity. But with this study being “virtually certain” that glacier retreat is caused by climate change, perhaps people will be more motivated to work toward reducing the effects of climate change.