A 44-square-mile section of Greenland's ice shelf has broken off in the last two years, researchers said.
The lost ice represents an area about twice the size of Manhattan.
Scientists fear the ice shelf, the biggest outside Antarctica, is melting even more rapidly than previously predicted.
"We should be very concerned about what appears to be progressive disintegration at the Arctic's largest remaining ice shelf, because upstream ... is the only major Greenland ice sheet ice stream," Jason Box, a spokesperson for The Geological Survey of Denmark and Greenland said in a statement.
The acceleration of the ice shelf's melt "has really picked up these last couple of years," Box told CNN.
Researchers have tracked the disintegration of the ice shelf using satellite imagery.
Greenland, which is 79% covered in ice, had only lost 18 square miles of ice since 1999 before this new chunk fell off into the oceans, creating an armada of icebergs.
"The last few years have been incredibly warm in northeast Greenland," Jenny Turton, a researcher at Germany's Friedrich Alexander University said in a statement. "We had very early melt onset in 2019 linked to the heatwave across Europe and Greenland."
Researchers are convinced the ice shelf is being melted from above and below. Warmer surface water is getting into crevices on the ice and driving it apart. However, the general temperature of the sea is rising which means water is warming the bottom of the ice shelf, too.
"The atmosphere in this region has warmed by approximately 3 degrees Celsius since 1980 and record-breaking temperatures have been observed in 2019 and 2020," Turton added.
Climate activists said the planet is running out of time to prevent catastrophe.
"This is yet another alarm bell being rung by the climate crisis in a rapidly heating Arctic," Greenpeace Nordic Oceans Campaigner Laura Meller said in a statement.
Researchers from Ohio State University concluded in August that the ice shelf had melted to a point of no return. An area twice as large as the Greenland ice shelf broke away from the Arctic in Canada in July.
The same satellite images that determined the how much ice in Greenland had been lost found that the world has lost 530 billion tons of ice since 2019 causing the world's oceans to rise 1.5 millimeters.
