Since the early 2000s, three ice shelves, namely Ostenfeld, Zachariæ Isstrøm, and Hagen Bræ, have collapsed completely.
The ice shelves supporting northern Greenland’s glaciers have lost more than 35% of their total volume since 1978, according to a study published in Nature Communications journal.
The study was conducted by a group of scientists led by Romain Millan, a glaciologist at the Grenoble Alpes University in France.
The scientists analysed eight ice shelves buttressing glaciers in northern Greenland, using thousands of satellite images, along with climate models and measurements from the field.
Ice shelves are the part of ice sheets — a form of glacier — that float over water. They act as dams that hold back glaciers on land and slow ice loss. Thus, when they melt and weaken, more of the land-based ice can slide into the ocean, exacerbating sea level rise.
Since the early 2000s, three ice shelves, namely Ostenfeld, Zachariæ Isstrøm, and Hagen Bræ, have collapsed completely. In addition, Greenland’s five remaining ice shelves are rapidly weakening, destabilising the nearby glaciers and threatening potentially ‘dramatic’ consequences for sea level rise.
The glaciers of North Greenland are hosting enough ice to raise sea level by 2.1 m […]. This part of Greenland is buttressed by the last remaining ice shelves of the ice sheet. For the floating ice shelves that remain we observe a widespread increase in ice shelf mass losses. This may have dramatic consequences for the stability of Greenlandic glaciers, the scientists said.
The ice loss came from a mixture of factors. The predominant driver was basal melting, where warm ocean currents melt the ice from beneath. Between 2000 and 2020, there was a widespread increase in basal melt rates that closely follows a rise in the ocean temperature, the study found.
If the oceans continue to warm, it could permanently weaken the ice shelves, Millan said. And in a certain timescale, they could even collapse, which could have significant consequences on the contribution of the Greenland ice sheet to sea level rise.