Greenland’s Ice Sheet Surface Melt Is Accelerating While Antarctica’s Slows Down, Study Finds

According to a new study by researchers at the Netherlands’ Utrecht University and the University of California, Irvine (UCI), the rate at which Greenland’s surface ice has been melting has increased in recent decades, while surface ice melt in Antarctica has slowed.

For the study, the researchers examined the role that katabatic and Foehn winds — downslope gusts that bring dry, warm air rushing to the tops of glaciers — play in the melting of Greenland’s ice sheet. They said that, in the past decade, melting related to the winds has increased more than 10 percent in Greenland, but their impact on Antarctica’s ice sheet has gone down by 32 percent.

“We used regional climate model simulations to study ice sheets in Greenland and Antarctica, and the results showed that downslope winds are responsible for a significant amount of surface melt of the ice sheets in both regions,” said co-author of the study Charlie Zender, UCI professor of Earth system science, in the press release. “Surface melt leads to runoff and ice shelf hydrofracture that increase freshwater flow to oceans – causing sea level rise.”

The study, “Wind-Associated Melt Trends and Contrasts Between the Greenland and Antarctic Ice Sheets,” was published in the journal Geophysical Research Letters.

Though the winds’ impact was substantial, Zender said the earmarks of global warming were having contrasting influences in the Southern and Northern hemispheres.

Surface melt due to the wind was being exacerbated by Greenland “becoming so warm that sunlight alone (without wind) is enough to melt it,” Zender said.

Warmer surface air temperatures, along with the 10 percent increase in melt driven by the wind, have resulted in 34 percent more total surface ice melt. Zender attributes this partially to global warming’s influence on the index differential of sea level pressure, the North Atlantic Oscillation (NAO).

NAO’s shift to a positive phase led to below-normal high latitude pressure, which brought warm air to Greenland and other areas in the Arctic.

On the other hand, since 2000, Antarctica has seen a decrease in total surface melt of about 15 percent. The reduction is due in great part to the Antarctic Peninsula having 32 percent less wind-generated downslope melt in the same area where two ice shelves collapsed.

Zender pointed out that the ozone hole in the Antarctic stratosphere, discovered in the 1980s, is still recovering, providing the surface with temporary insulation from additional melt.

“The ice sheets in Greenland and Antarctica keep over 200 feet of water out of the ocean, and their melt has raised global sea level by about three-quarters of an inch since 1992,” Zender said in the press release. “Although Greenland has been the No. 1 driver of sea level rise in recent decades, Antarctica is close behind and catching up and will eventually dominate sea level rise. So it’s important to monitor and model melt as both ice sheets deteriorate, including the ways climate change alters the relationship between wind and ice.”