Research aided by the University of Minnesota published last Wednesday found that meltwater on the surface of Greenland’s glaciers moves through cracks, gets trapped beneath the ice and creates lakes that heat the ice from below.
It’s been widely known for about a decade that Greenland’s glaciers have been melting increasingly fast on the surface. But the new research — which was published in the journal “Nature” — shows the ice-melting process is adding sea water, potentially contributing to higher sea levels worldwide.
“[Greenland is] changing like crazy,” said Michael Willis, lead researcher and Cornell University geological sciences professor. “You can see the changes going on, and they’re going on rapidly.”
Willis has been mapping the ice sheet for about three years, using data collected from high-resolution satellite images from the University’s Polar Geospatial Center, as well as data from IceBridge, a NASA operation that monitors polar ice sheets, glaciers and sea ice to predict models of sea-level rise.
Originally, Willis was mapping the ice sheet to measure ice melting on the surface of Greenland’s glaciers. But while he was looking over images in 2011, he saw a peculiar dark spot in Greenland’s northeast.
“My initial impression was, ‘Oh, this is a glitch. There’s something wrong,’” Willis said, “‘or there’s a smudge, or something like that, over the sensor.’”
But the “smudge” was actually a 70-meter-deep basin, or depression, in the ice.
Willis considered the new theory: meltwater from the surface could have pooled in a lake beneath and eventually burst into the sea, causing the ice to drop. This idea was new, he said, since meltwater typically travels immediately to sea.
Willis then came to the Polar Geospatial Center to collect satellite images at a high enough resolution to confirm his theory.
The center, founded in 2007, allows any federally-funded researcher access to a massive library of high-profile satellite images. They can also monitor the arctic region they’re studying in real time.
“We used the dataset to get an accurate two- or three-year picture of what’s going on with this basin,” said Polar Geospatial Center cartographer Brad Herried, who contributed to the research.
The images collected, along with research from Ohio State University and Columbia University, confirmed that the lake beneath the glacier not only filled and disbursed, but also rapidly filled again — and that cycle may continue.
Greenland is transforming quickly — it lost about five times more mass in the past couple of years than it did during all of the 1990s, Willis said.
Glaciers in other regions, such as Alaska, are considered wet glaciers, which are very mobile and experience a lot of meltwater activity. Glaciers in Greenland, however, are typically dry because the country is so far north and very cold.
Dry glaciers usually stick to the land beneath them and don’t move around much. But Willis’ discovery could mean that Greenland’s glaciers may someday behave like the wet glaciers in Alaska.
“With melting like [this] … we’d have to expect it to change the large-scale behavior of the ice sheet,” study co-author and Ohio State professor Michael Bevis said in a press release.
Recent research by the University of California-Los Angeles found that not all surface meltwater in Greenland has made its way to sea, which means that there could be more trapped lakes like the one Willis found.
“Thinking about these sub-glacial lakes in Greenland … we don’t know much about them,” Herried said. “So now that we know where one is, I think that there’s definitely going to be an eye kept on these types of things.”