Research suggests Greenland’s northern ice shelves have shrunk by a third since 1978

by Tara Suter - 11/08/23 2:12 PM ET

This Aug. 16, 2010, image provided by NASA Earth Observatory shows a piece of the Petermann Glacier that cracked in Greenland. A study in the Proceedings of the National Academy of Sciences on Monday, May 8, 2023, found that tides and climate change are rapidly melting ice in the grounding line zone of the Petermann Glacier. That’s the point where glaciers go from being on land to floating on water. (Jesse Allen and Robert Simmon/NASA Earth Observatory via AP)

New research suggests Greenland’s ice shelves have shrunk by around a third since 1978.

A study published Tuesday in the journal Nature Communications said the ice shelves in the northern part of the country have lost more than 35 percent of their total volume. The study also said three ice shelves in the region have collapsed “completely.”

According to the National Snow and Ice Data Center (NSIDC), part of the Cooperative Institute for Research In Environmental Sciences at the University of Colorado Boulder, ice shelves are “floating tongues of ice that extend from glaciers grounded on land.”

“Ice streams and glaciers constantly push on ice shelves on their upstream side,” a webpage about ice shelves on the NSIDC website reads. “As the large plates of ice spread over the ocean, many shelves come up against coastal features such as islands, peninsulas, or submerged mountains, creating a resisting pressure that slows their movement toward the ocean.”

“If an ice shelf collapses, this backpressure disappears,” the webpage continues. “The brakes on glacier flow are released. The glaciers that fed into the ice shelf speed up, flowing more quickly out to sea. Glaciers and ice sheets rest on land, so once they flow into the ocean, they contribute to sea level rise.”

The study also noted the glaciers in North Greenland have ice that can “raise sea level by 2.1 meters” and have long been considered to be stable. In imperial measurement, that’s about 7 feet. The study also noted an increased rate of “basal melting,” which is defined as “the melting of the ice shelves from underneath” by NASA.

“Between 2000 and 2020, there was a widespread increase in basal melt rates that closely follows a rise in the ocean temperature,” the study said. “These glaciers are showing a direct dynamical response to ice shelf changes with retreating grounding lines and increased ice discharge.”

“These results suggest that, under future projections of ocean thermal forcing, basal melting rates will continue to rise or remain at high level, which may have dramatic consequences for the stability of Greenlandic glaciers,” the study continued.

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