Thanks to global warming, algae are expanding on Greenland, helping to slowly melt the massive island's ice sheet and turning it "green."

The microscopic algae that grow on the Greenland ice sheet are dark, which means they absorb more sunlight and warm up the surface more quickly than white ice, which reflects light.

"More algae means a darker surface, and darker surfaces melt faster," said Martyn Tranter, head of the British research project Black and Bloom, the first group to study the phenomenon.

As this feedback loop continues, the extra warming from increased algae coverage causes a more rapid melting of the ice sheet. That's a problem because if all the ice on Greenland melted, sea levels would rise by as much as 20 feet in spots worldwide, inundating coastal cities.

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Snow and ice reflect up to 90% of solar radiation, according to NASA. Dark algae areas, on the other hand, only reflect roughly 35% or even as little as 1% in the darkest spots, the Black and Bloom group said.

The process, scientifically called albedo, is similar to how white clothes feel cooler on hot days, while black clothes heat up, Tranter said.

Climate change will likely only exacerbate the process by providing more melt water for microorganisms like algae to thrive in, the Black and Bloom group said.

Roughly 85% of the massive island in the North Atlantic Ocean is covered with a colossal ice sheet, and has been for centuries. While algae were first spotted on Greenland over 100 years ago, their potential impact hasn't been studied until recently.

In addition, warming temperatures alone have already taken a toll on the ice: Greenland has lost about 4,000 gigatons of ice since 1995. That's turned into roughly 1 quadrillion gallons of water, said Stefan Hofer of the University of Bristol in the United Kingdom.

Recent studies have also sounded dire warnings about Greenland ice and sea-level rise.

One found that over the past two decades, unusually sunny summer days have caused huge amounts of ice to melt in Greenland. Another found sea-level rise is accelerating nearly three times as rapidly now as during the 20th century. And a third attributed 25% of the average global sea-level rise in 2014 to mass loss from the Greenland ice sheet.