The ice caps around Greenland and Antarctica are shrinking, and a study published on Monday in Nature Climate Change suggests that we’re likely to see some ice melt this summer.
That’s a bit worrisome, since the ice is crucial to the continent’s energy flow, and in some places it provides as much as 20 percent of its annual energy needs.
“We’re already seeing signs of some retreat, and the ice cap is shrinking rapidly,” says lead author and glaciologist Mark Williams, a postdoctoral researcher at the University of California, Berkeley.
“There’s some uncertainty around what the impact will be, and we don’t know how much.”
Williams and his colleagues have been studying the ice since the 1970s, studying its interactions with sea ice in Greenland and Antarctic, and analyzing satellite data to understand how it’s changing over time.
This study uses data from the National Snow and Ice Data Center, a collection of hundreds of satellite images taken over the last decade.
This data is used to estimate the rate of melting of the ice caps in Greenland, as well as its potential for further retreat.
It’s been known that the ice on the Greenland ice sheet is losing mass at a rate faster than the planet’s surface, but the rate has never been measured directly.
To make sure this rate is happening at a steady rate, Williams and his team looked at the satellite images to figure out how fast the ice was melting.
“This is the first study to quantify how fast these ice loss rates are changing, and it’s really a landmark study,” Williams says.
“We’ve been following the ice sheet and we’ve been able to get some pretty good estimates of how fast it’s been retreating.”
Using satellite data, the team measured the rate at which the ice had melted at different times during the past decade.
The average rate of loss per month, measured from 2002 to 2014, is about 1.5 millimeters per year.
At the same time, the ice surface has grown in thickness.
This has caused the rate to decrease.
“It’s not the absolute amount that we think is causing the loss of ice, but rather the rate that the water is being absorbed into the ice,” Williams explains.
“That’s what we’re trying to determine.”
When we compare the rates of ice loss and loss per year, we’re seeing some significant change, but it’s not clear how big this change is, he says.
The authors do not have the data to compare it to climate models.
That uncertainty is what makes the study so important, because it suggests that the pace of ice-loss may not be as rapid as some climate models have suggested.
“This is not something that we expect to see happening in the near future,” Williams adds.
The loss of the Greenland glaciers is one of the fastest changes seen in the world, and there are several other glaciers that have retreated faster than Greenland’s, including the Amundsen Sea and the Larsen C ice shelf.
It’s also not clear if the rate is accelerating, because the authors do only have data for two years of the year.
“If we assume that the rate remains constant for the next decade, then this could be a very interesting study,” says Kevin Anderson, a professor of earth system science at the Massachusetts Institute of Technology, and one of Williams’ co-authors.
“It’s a really nice reminder of what we’ve learned about climate change.”
The authors note that it’s likely that more ice will melt in coming years.
“But we don