The oldest and thickest sea ice in the Arctic zone north of Greenland is splitting in a never-before-seen event. The waters found there are so cold, they have been frozen for as long as records exist — even during summer months. For the second time this year, the frozen waters cracked open to reveal the sea beneath them in an event that scientists are calling “scary.”

The ice found in the Arctic area north of Greenland is usually compact and unbreakable as a result of the Transpolar Drift Stream, which pushes ice from Siberia across the Arctic Sea, where it packs up on the coastline. The breaking sea ice is a result of a climate-change-driven heatwave that caused abnormal spikes in temperatures both this month and in February 2018.

Related: Previously stable zones of Antarctica are now falling victim to climate change

This phenomenon has never been recorded before and is said to be caused by warm winds striking the ice pileup on the Arctic coastline. “The ice there has nowhere else to go, so it piles up,” said Walt Meier from the U.S. National Snow and Ice Data Center. “On average, it’s over four meters thick and can be piled up into ridges 20 meters thick or more. This thick, compacted ice is generally not easily moved around.” However, 2018 is seeing the lowest ever recorded sea ice volume since 1979, according to satellite data.

“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 said. “Open water off the north coast of Greenland is unusual. This area has often been called ‘the last ice area’ as it has been suggested that the last perennial sea ice in the Arctic will occur here.”

Related: Migratory barnacle geese threatened by rapidly rising Arctic temperatures

The event is proving worrisome for climate scientists who explain that the longer the patches of water remain open, the easier it will be for the sea ice to be pushed away from the coast and melt. “The thinning is reaching even the coldest part of the Arctic with the thickest ice,” Meier said. “So it’s a pretty dramatic indication of the transformation of the Arctic sea ice and Arctic climate.”

Via The Guardian

Image via U.S. Geological Survey