The lower portion of Alaska’s Kennicott Glacier is covered by a layer of debris. This debris is made up of rocks, sediment, soot, dust, and volcanic ash and is challenging to measure and account for in models as the debris thickness varies considerably over the glacier. NASA / Courtesy of David Rounce
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A new analysis funded by NASA and conducted in conjunction with its High Mountain Asia Team and Sea Level Change Team has found that with 1.5 degrees Celsius of global heating above pre-industrial levels, half the world’s glaciers would disappear and cause sea levels to rise 3.5 inches by the year 2100.
From 2013 to 2017, David Rounce, an assistant professor at Carnegie Mellon University, and his research team measured the Imja-Lhotse Shar Glacier near Mount Everest’s base in the Himalayas as it quickly receded. As the glacier melted, the lake at the base of the famous mountain filled up, a press release from NASA said.
“To go to the same place and to see the lake expand and see how the glacier was thinning rapidly was quite eye-opening to say the least,” Rounce said in the press release.
Rounce led a study in January that predicted Earth’s glaciers could shrink by up to 40 percent by 2100.
The study, “Global glacier change in the 21st century: Every increase in temperature matters,” was published in the journal Science.
In their analysis, the research team modeled the planet’s glaciers, except the Antarctic and Greenland ice sheets, in order to make projections of how they would be affected by temperature increases from 1.5 to four degrees Celsius, the press release said.
While they found that half the world’s glaciers would melt at 1.5 degrees Celsius of warming, if the planet warms by 2.7 degrees Celsius, which is the predicted temperature increase based on COP26 climate pledges, almost all of the glaciers in western Canada, the U.S. (including Alaska) and Central Europe would disappear. If temperatures warm by four degrees Celsius, 80 percent of Earth’s glaciers would be gone and cause sea levels to rise by six inches.
“Regardless of temperature increase, the glaciers are going to experience a lot of loss,” Rounce said in the press release. “That’s inevitable.”
The study by Rounce and his team was the first to use mass change data taken from satellites of all 215,000 of the planet’s glaciers.
“Sea level rise is not just a problem for a few specific locations,” said leader of NASA’s Sea Level Change Team Ben Hamlington in the press release. “It’s increasing almost everywhere on Earth.”
The model took into account glacial debris cover, including sediment, soot, dust, rocks and volcanic ash on the surface of glaciers. Glacial debris can affect melting — a thin layer can cause more while a thick layer can provide insulation that reduces it.
Especially strong indicators of climate change are glaciers located in remote parts of the planet.
“We are not trying to frame this as a negative look at the loss of these glaciers, but instead how we have the ability to make a difference,” Rounce said in the press release. “I think it’s a very important message: a message of hope.”