Greenland’s glaciers are melting 100 times faster than previously calculated, according to a new model that accounts for the unique interaction between ice and water on the island’s fjords.
The new mathematical representation of glacier melt takes into account the latest observations of how ice is being eaten away from the steep vertical surfaces at the ends of glaciers in Greenland. Previously, scientists used models developed in Antarcticwhere glacial tongues float on sea water – a very different arrangement.
“For years, people took the melting rate model for floating glaciers in Antarctica and applied it to them Greenland‘s vertical glacier fronts”, lead author Kirstin Schulza research associate at the Oden Institute for Computational Engineering and Sciences at the University of Texas at Austin said in a expression. “But there is growing evidence that the traditional approach to Greenland’s vertical glacier fronts produces melt rates that are too low.”
The researchers published their findings in the journal in September Geophysical Research Letters.
The researchers already knew that their Antarctic understanding of Arctic glaciers didn’t add up perfectly. But it’s difficult to approach the edges of Greenland’s glaciers, as they lie at the ends of fjords — long, narrow seawater inlets flanked by high cliffs — where warm water erodes the ice. This leads to dramatic calving events, in which chunks of ice the size of buildings crumble into the water without warning, creating mini-tsunamis, the researchers said.
Researchers led by a physical oceanographer Rebekah Jackson from Rutgers University use robotic boats to approach these dangerous ice cliffs and take measurements. They have done this at LeConte Glacier in Alaska, as well as at Kangerlussuup Sermia in Greenland. (An upcoming mission led by scientists at the University of Texas at Austin will turn robotic submarines into the faces of three West Greenland glaciers.) Jackon’s measurements indicate that the Antarctic models massively underestimate Arctic glacial melt. LeConte, for example, is disappearing 100 times faster than models predicted.
The mix of cold freshwater from the glaciers and warmer seawater drives ocean circulation near the glaciers and further out in the ocean, meaning the melt is having widespread effects. The Greenland ice sheet is also important for sea level rise; Greenland ice holds enough water to raise sea levels by 6 meters.
The new model uses the latest data from missions near glaciers, as well as a more realistic understanding of how the steep, cliff-like walls of glaciers affect ice loss. The results are consistent with Jackson’s findings and show 100 times more melt than the old models predicted.
“The results of ocean climate models are extremely relevant for humanity to use to predict trends related to climate change, so you really want to get them right,” Schulz said. “That was a very important step in making climate models better.”