The oldest and thickest sea ice in the Arctic has started to break up for the first time, in a development one scientist called “scary.” The breaking of the ice has opened up waters north of Greenland that are normally frozen, even in the height of summer. The phenomenon has never been recorded before— but has now happened twice this year, according to The Guardian, due to warm winds and a climate-change driven heatwave. Scientists said the finding could force a rethink about which part of the Arctic will withstand climate change the longest. The area is normally so solidly frozen that is was known as “the last ice area” because it was assumed it would last the longest against warming. “Almost all of the ice to the north of Greenland is quite shattered and broken up and therefore more mobile,” said Ruth Mottram of the Danish Meteorological Institute.