Northern Greenland’s floating ice shelves, which play a crucial role in regulating the amount of fresh water released into the ocean, have lost more than a third of their volume since 1978, scientists warn in a study published Tuesday, November 7.

Researchers stationed in Denmark, the United States and France used thousands of satellite images, combining them with field measurements and models to reconstruct the evolution of these platforms which extend the glaciers onto the water .

“Since 1978, the ice shelves of northern Greenland have lost more than 35% of their total volume, with three of them collapsing completely,” of the eight present in the region, the authors conclude in the journal Nature Communications.

“The main reason is that they melted below with the warming of ocean waters,” Romain Millan, researcher at CNRS and the University of Grenoble, lead author of the study, explains to AFP. “We have highlighted a very significant increase in melting since the 2000s, which obviously corresponds to the increase in ocean temperatures in this sector and during this period,” he continues.

Alarming conclusions

The melting of these platforms does not directly contribute to the rise in ocean levels. On the other hand, said platforms play the role of a “dam” regulating the quantity of frozen fresh water coming from the cap, discharged into the ocean and which, in turn, participates in this phenomenon.

The disappearance of these natural dams therefore has significant effects on glaciers, whose anchor points on the ground are retreating and which are dumping more ice than before. “For example, the Zachariae Isstrom glacier, which lost its platform in 2003, then almost doubled the quantity of ice it discharged into the ocean,” notes Romain Millan.

These conclusions are all the more alarming because the glaciers in this region were previously considered stable by scientists, unlike other, more sensitive areas of the polar ice cap which began to weaken in the mid-1980s. “What will happen at the poles and sea levels in the future will depend on the decisions that will be taken by policies to reduce greenhouse gas emissions,” recalls the researcher, a few weeks before the COP28 on climate, to be held in Dubai from November 30 to December 12.