Two lakes under ice in Greenland have unexpectedly disappeared, which some climatologists believe could be a sign of dramatic climate change in the region.
One of the lakes stretched two miles across under the frozen landscape. That formation has dried completely drained twice since 2012. At one time, a sub-surface blowout drained 57,000 gallons of water from the body every second. That is roughly the volume of a large backyard pool.
Another subglacial lake once held seven billion gallons of water, drained from melting ice caps. Researchers believe the lake may have become overwhelmed by melting ice formations, overwhelming natural systems.
Greenland is especially important to climate studies, as the nation experiences global warming 50 percent greater than the global average. As temperatures there continue to rise, climatologists believe melting of the Greenland ice will become more pronounced. Ice reflects much of the light and heat that strikes it, reflecting energy back into space. As ice melts, exposing water, additional heat is absorbed by the ocean, contributing to regional warming. This can result in a feedback cycle, which can melt additional ice. As sheets expand, they can spread to lower, warmer, elevations, creating a second feedback cycle in the region.
"Many studies of sea level rise don't take into account feedbacks that could cause rapid sea level rise. We wanted to look at the effects of those feedbacks," Patrick Applegate of Penn State, said.
Climatologists calculate that if all the ice in Greenland were to melt, average sea levels around the world would rise by 24 feet. However, storm surges provide additional risks of flooding in areas which might normally be protected from flooding. New York City, for example, has seen an increase in sea level of just one foot over the last century. Hurricane Sandy in 2012, however, flooded subways in America's most-populous city.
Although floating ice does not contribute to the rise of sea levels as it melts, the Greenland ice sheet is located on bedrock.
Researchers examined a pair of computer climate models, in an effort to determine how rising temperatures altered melting of the massive ice sheet. The results showed that melting occurs at a faster rate as temperatures increase.
"If enough water is pouring down into the Greenland Ice Sheet for us to see the same sub-glacial lake empty and re-fill itself over and over, then there must be so much latent heat being released under the ice that we'd have to expect it to change the large-scale behavior of the ice sheet," Michael Bevis of Ohio State University said.
The two cases of sudden disappearances of a pair of subglacial lakes in Greenland were profiled in an article in Nature, as well as detailed in the journal The Cryosphere.
