Some of the oldest and thickest sea ice along the northern coast of Greenland has started breaking up after remaining frozen year after year, The Guardian reported on Tuesday. Warm winds and a heatwave led to the unprecedented phenomenon twice this year already – in February and earlier this month.

This part of the Arctic normally stays frozen even during summers, and has often been described as the “last ice area”. However, the ice is now further away from the coast than it has ever been since satellite records began in the 1970s.

“Almost all of the ice to the north of Greenland is quite shattered and broken up and therefore more mobile,” Ruth Mottram of the Danish Meteorological Institute told The Guardian. “Open water off the north coast of Greenland is unusual.”

Sea ice scientist Peter Wadhams told The Independent: “In the past, most of the ice in the Arctic has been multi-year ice, but that has been shrinking and now nearly all the ice in the Arctic is first-year ice. The only zone where multi-year ice has survived is north of Greenland, but this last holdout is now opened up and moving away from the coast.”

The phenomenon will have a potentially catastrophic effect on polar bears and seals, leading scientists told The Independent. If this ice continues to break up, it will leave little to no ice for wildlife to hunt on.

“They [polar bears] can’t swim very far,” Wadham said. “If this becomes a permanent feature with ice away from the coast, polar bears won’t have any ice to hunt on. You would lose the polar bear habitat.”

Research scientist Walt Meier told The Guardian: “The thinning is reaching even the coldest part of the Arctic with the thickest ice. So it’s a pretty dramatic indication of the transformation of the Arctic sea ice and Arctic climate.”

Both instances of the ice breaking up this year were driven more by wind than melting, as temperatures rose higher than normal. Earlier this year, there were 10 days above freezing point at a weather station that is usually below minus 20 degrees Celsius in February. In August, the station briefly recorded 17 degrees Celsius, a record high, according to The Guardian.