When scientists study the consequences of climate change on Greenland’s ice, they typically give attention to the ice sheet— the large, contiguous body of ice that covers some 80 percent of the island. But there are millions of peripheral glaciers separate from the ice sheet along Greenland’s coast, they usually’ve been little studied — until now.
Using a mix of historical aerial photographs and satellite imagery of Greenland, scientists have now analyzed the movement of greater than 1,000 peripheral glaciers from 1890 to 2022. And, unfortunately, the outcomes are bleak. In line with the researchers, the speed of retreat for these peripheral glaciers has doubled within the last 20 years.
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“Peripheral glaciers only represent about 4 percent of Greenland’s total ice-covered area, but they contribute 14 percent of the island’s current ice loss — a disproportionately large portion,” Laura Larocca, a climate and geospatial scientist who served as first writer on a study in regards to the findings, said in an announcement. “For those who look globally in any respect glaciers which can be distinct from the Greenland and Antarctic Ice Sheet, they’ve contributed roughly 21 percent of observed sea level rise over the past 20 years. So, these smaller ice masses are a very important a part of the sea level problem.”
The historical aerial photographs of Greenland were crucial to the team’s evaluation. Earth-observing satellites weren’t launched until the Nineteen Seventies so, for a very long time, scientists had believed detailed observational records of Greenland’s peripheral glaciers didn’t exist until that time. But 15 years ago, an archive of old photographs was discovered in a castle in Greenland, including images of the country’s coastline. These images were taken by pilots in open-cockpit airplanes.
“Those old photos extend the dataset back prior to the satellite era, when widespread observations of the cryosphere are rare,” Yarrow Axford, the William Deering Professor in Geological Sciences at Northwestern University, said within the statement. “It’s quite extraordinary that we will now provide long-term records for a whole bunch of glaciers, finally giving us a chance to document Greenland-wide glacier response to climate change over greater than a century.”