Melting due to the Foehn effect increases in Greenland and decreases in Antarctica

2023-10-17 11:28:21

Greenland is dotted with frozen meltwater lakes – NASA OPERATION ICEBRIDGE

MADRID, 17 Oct. (EUROPA PRESS) –

Surface ice in Greenland has been melting at an increasing rate in recent decades, while the trend in Antarctica has moved in the opposite direction.

For an article recently published in Geophysical Research Letters, Scientists at the universities of California Irvine and Utrecht studied the role of the Foehn effect and katabatic winds, downward gusts that bring warm, dry air into contact with the tops of glaciers. They conclude that the melting of the Greenland ice sheet related to these winds has increased more than 10% in the last 20 years; The impact of winds on the Antarctic ice sheet has decreased by 32%.

“We used regional climate model simulations to study ice sheets in Greenland and Antarctica, and the results showed that downward winds are responsible for a significant amount of surface melting of ice sheets in both regions,” he said. it’s a statement co-author Charlie Zender, professor of Earth system sciences at Irvine. “Surface melting causes ice shelf runoff and hydrofracturing that increases the flow of freshwater to the oceans, causing sea level rise.”

While the impact of winds is substantial, he said, the different behaviors of global warming in the northern and southern hemispheres are causing contrasting results in the regions.

In Greenland, wind-driven surface melt is exacerbated by the fact that the huge island “it becomes so warm that sunlight alone (without wind) is enough to melt it”, according to Zender. The 10% growth in wind-driven melt combined with warmer surface air temperatures has resulted in a 34% increase in total surface ice melt. He attributes this result in part to global warming’s influence on the North Atlantic Oscillation (NAO), an index of sea level pressure difference. The change of the NAO to a positive phase has caused below normal pressure at high latitudes, which has caused warm air to reach Greenland and other areas of the Arctic.

The authors found that, unlike Greenland, total Antarctic surface melt has decreased by about 15% since 2000. The bad news is that this reduction is largely due to 32% less wind-generated melt in the Antarctic Peninsula, where two vulnerable ice zones are located. Zender said it is fortunate that the Antarctic stratospheric ozone hole discovered in the 1980s continues to recover, which temporarily helps insulate the surface from further melting.

“The Greenland and Antarctic ice sheets keep more than 70 meters of water out of the ocean, and their melting has raised global sea level by about 1.90 centimeters since 1992,” Zender said. “Although Greenland has been the main driver of sea level rise in recent decades, Antarctica is close behind and is catching up and will eventually dominate sea level rise. Therefore, it is important to monitor and model melting as both ice sheets deteriorate, including the ways in which climate change alters the relationship between wind and ice.”

He said he hopes research into the role of the Foehn effect and katabatic winds in the polar regions will help the climate science community strengthen the physical fidelity of Earth system models.