In December of 2019, NASA scientists released a new series of time-lapse videos of images of the glaciers in Alaska, Greenland, and Antarctica. All three series of images show how glacial retreat has spread across the polar regions as oceans have continued to warm, but one in particular, the glaciers over Alaska and the Yukon, has caused concern, if not outright alarm.
Using images from the Landsat mission from 1972 through 2019, University of Alaska Fairbanks glaciologist Mark Fahnestock stitched together a video of six-second time lapses of every glacier in Alaska and the Yukon, and the news isn’t good.
“We now have this long, detailed record that allows us to look at what’s happened in Alaska,” Fahnestock said. “When you play these movies, you get a sense of how dynamic these systems are and how unsteady the ice flow is.”
The videos, created with software to reprocess the images and computing power from Google Earth Engine, demonstrate the glacier changes as the climate warms, he said, and they show how different glaciers respond in varied ways to those changes. Some show lakes forming where ice used to be; others show debris from landslides making its way to the sea, and surges that pause for a few years. All in all, these time-lapse videos are giving scientists some new hints about what drives glacier changes.
The Columbia Glacier, for example, was pretty stable when Landsat was launched in 1972. But starting in the mid-1980s, the glacier’s edge began retreating rapidly. By 2019, the glacier’s front had retreated more than 12 miles upstream. By way of contrast, the Hubbard Glacier has advanced 3 miles in the last 48 years. However, the 2019 image of Hubbard shows a large indentation where ice has broken off.
“That calving embayment is the first sign of weakness from Hubbard Glacier in almost 50 years—it’s been advancing throughout the historical record,” Fahnestock said. “The satellite images also show that these types of calving embayments were present in the decade before Columbia retreated.”
The news isn’t particularly good in Greenland, either. Michaela King of Ohio State University analyzed Landsat data back to 1985 in order to study more than 200 of Greenland’s large outlet glaciers. She found that Greenland’s glaciers have retreated an average of about 3 miles between 1985 and 2018, and the most rapid retreat occurred between 2000 and 2005.
“These glaciers are calving more ice into the ocean than they were in the past,” King said. “There is a very clear relationship between the retreat and increasing ice mass losses from these glaciers during the 1985-through-present record.”
Watch this video to see time-lapse photos of Earth’s glaciers and ice sheets as seen from space. It also provides an explanation of the significance of these glacier changes.
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