Over 65,000 Supraglacial Lakes Discovered on the East Antarctic Ice Sheet: 'It's Concerning'

Scientists are concerned about the rapid rate at which Antarctica's largest ice sheet is melting, with a study recently published in Science Advances finding the number of meltwater lakes on the East Antarctic Ice Sheet are significantly higher than previously thought.

The team led by researchers at Durham University in the U.K. used high-resolution satellite imagery to identify more than 65,000 supraglacial lakes (bodies of water that sit on the surface of a glacier) across around two million square miles—including regions of the ice sheet where melting was thought to be less severe.

But even this is a minimum, the study author's say. Smaller lakes may have been missed off the count, while others that were included in the figure may pick up more meltwater—and grow in size—during warmer months.

"The key implication is that the formation of the lakes is far more widespread than previously thought," lead author Chris Stokes told Newsweek. "This suggests that the ice sheet may be more vulnerable to a warming climate than previously thought."

This is the first time researchers have attempted to map out the number of lakes lying on the surface of the ice sheet during peak melt season—it is an effort that would not have even been possible only a few years ago. Now, using satellite images from January 2017—during the summer melt season—Stokes and his team have been able to determine where lakes are forming in the greatest numbers due to surface melt and, thus, the areas that might be most under threat from climate change.

It is only recently that reports of these lakes in the East Antarctic Ice Sheet even existed, although it has become clear that they are more prevalent than previously thought.

The researchers found that many of the lakes detected are the size of a standard swimming pool—but at least one was more than 27 square miles. Most form within a few miles of the coastline but some were found hundreds of miles inland at elevations up to 3,200 feet.

The study draws parallels between the East Antarctic Ice Sheet, the Greenland Ice Sheet and the Antarctic Peninsula. The latter two are thought to be warmer, therefore at greater risk from warming.

"Until recently we assumed that East Antarctica was too cold to be similarly vulnerable, but this work shows that there may be closer parallels here to our observations on Greenland than previously thought," co-author Amber Leeson, a doctor in Lancaster Environment Centre at Lancaster University, said in a press release.

A meltwater lake at Mawson Glacier, East Antarctic Ice Sheet. Photo credit: Richard Selwyn-Jones, Durham University.

"It's concerning because we know that in other areas, large numbers of lakes draining can fracture apart floating ice shelves, causing the inland ice to speed-up."

Approximately 60 percent of the lakes were on floating ice shelves—some of which could collapse if the meltwater lakes get any bigger.

The melting is triggered by warmer waters around the Antarctic, which is attacking the floating sections of the sheet from below. The result: glacial melt speeds up, causing the glaciers to retreat and sea-levels to rise.

This is exacerbates the albedo effect—the process whereby reduced ice surface means less of the Sun's radiation can be reflected back into space, causing more to absorbed, which leads to more global warming.

"Some of these ice shelves almost act like a door-stop and, once they are removed, the ice further inland can increase in speed, discharging more ice into the ocean," Stokes told Newsweek.

"Whilst there is no imminent threat to the stability of the ice sheet from these lakes, our study has shown which areas we should be keeping an eye on over the next few years and beyond."

The team hopes these lakes can be used as a baseline measurement for future research, and they plan to conduct a similar survey in the near future.