Scientists have discovered previously collected floods under the Greenland ice sheet. This was spilled by force that could break through nearly 300 feet of solid ice.
This phenomenon occurred in 2014, causing 24 billion gallons (90 billion liters) of meltwater, punching it out of a glacial lake beneath the ice sheet. This is the first time such an event has been documented in the country.
By studying the sudden cascade, scientists say they will get important information about how local ice is melting, and how the destructive effects of this process melt into other sheets of Greenland sheets. They published their findings in the Journal of Natural Geoscience on Wednesday (July 30th).
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“When I first saw this, it was so unexpected that I thought there was a problem with our data,” a study by Jade Bowling, a glaciologist at Lancaster University, said in a statement. “But as we went deeper into the analysis, it became clear that what we were observing was the aftermath of a major flood escaped under the ice.”
“The presence of subglacial lakes beneath the Greenland ice sheets is still a relatively recent discovery, and as our research shows, we still don’t know much about how they evolve and how they affect the ice sheet system,” Bowling added.
The Greenland ice sheet is one of the only permanent ice sheets on Earth, and the other is the Antarctic ice sheet. Nearly three times the size of Texas, it covers about 656,000 square miles (1.7 million square kilometers) and loses an estimated 33 million tonnes of ice per hour, according to the US National Snow and Ice Data Center (NSIDC) in Colorado.
Related: Scientists record “icy trembling” deep inside Greenland’s frozen rivers
Little is known about the role of meltwater from the ice sheet. Scientists previously thought it would flow from the surface to the base before it flows into the ocean. A new study examined subglacial lakes where liquid water bodies trapped under ice – tend to be fed into meltwater.
Researchers suggest that these lakes can donate huge amounts of water to the ocean through drainage events, but as recently discovered, they are still not well understood.
Using satellite data, the team identified a previously unknown ice age lake north of Greenland and discovered a massive flood event that destroyed ice from below.
After the suites of satellites ripened the data collected by the European Space Agency’s Sentinel-1, Sentinel-2, and Cryosat-2), scientists were able to create 3D models of subglacial floods.
This revealed that a crater 0.77 square miles (2 square kilometers) wide, 279 feet (85 m) deep had been blown up from the ice sheet over a 10-day period between July and August 2014. The enormous deluge is roughly equivalent to nine hours of peak flow at Niagara Falls.
Further downstream, scientists found that the surges destroyed a large area of ice, leaving behind a raised block of ice that stood 82 feet (25 m) high, washing away an ice surface about twice the size of New York’s Central Park.
The findings contradict past expectations about how molten water flows through ice sheets before it normally penetrates the ocean, as well as contradict models in which the sheet predicts solids are frozen on its base.
“What we found in this study surprised us in many ways,” said Amber Leeson, a glaciologist at Lancaster University, in a statement. “It taught me new and unexpected things about how ice sheets respond to extreme inputs of surface meltwater, and highlighted the need to better understand the complex hydrological systems of ice sheets, both now and in the future.”
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