Sea level threat as Greenland faces more meltwater events
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The vast melting of Greenland’s ice sheet caused by unusually high temperatures in 2012 had a lasting impact on its ability to absorb and store future meltwater, new research showed yesterday.
The authors said it was evidence of how one-off or rare weather events could have a lasting impact on Earth’s frozen spaces and affect global sea levels.
In summer 2012, much of the Arctic sweltered in a rare heatwave.
Using advanced modeling techniques, a team of researchers in the United States reanalyzed radar data collected by flights from NASA’s Operation IceBridge between 2012-2017.
Ice sheet regions that haven’t undergone extreme melting can store meltwater through their upper 50 meters or so, preventing it from flowing into the ocean. But the team found that the melting in 2012 had refrozen into a layer of slick ice, creating slippery conditions that can speed up its movement and send chunks into the ocean. In some parts of the Greenland Ice Sheet, the team found that the melt layer had reduced its storage capacity to just 5 meters.
“When you have these extreme, one-off melt years, it’s not just adding more to Greenland’s contribution to sea-level rise in that year,” said lead study author Riley Culberg, from Stanford University.
“It’s also creating these persistent structural changes in the ice sheet itself.”
The Greenland Ice Sheet has experienced five record-breaking melt seasons since 2000, most recently in 2019.
Satellite data from 2021 showed that in the course of just a few July days, as much as 97 percent of the ice sheet surface had thawed.
And with the poles warming significantly faster than the rest of the planet, more extreme and regular hot weather over the Arctic is set to increase Greenland melt events.
“Normally we’d say the ice sheet would just shrug off weather — ice sheets tend to be big, calm, slow things,” said Dustin Schroeder, assistant professor of geophysics at Stanford’s School of Earth, Energy and Environmental Sciences.
“This really is one of the first cases where you can say, shockingly in some ways, these slow, calm ice sheets care a lot about a single extreme event in a particularly warm year.”
The Greenland Ice Sheet contains enough frozen water to raise global sea levels around 6 meters.
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