Greenland’s ice surface has been experiencing an accelerated rate of melting in recent years, while Antarctica is witnessing a contrasting trend, according to a team of experts led by the University of California, Irvine (UCI) and Utrecht University in the Netherlands.
In a study released in the American Geophysical Union’s journal Geophysical Research Letters, the team delved into the impact of Foehn and katabatic winds on glacial formations. These winds, which move downslope, carry warm, dry air, coming into contact with the glacier summits.
In the past 20 years, the melting associated with downslope winds in Greenland has increased by over ten percent. In stark contrast, the influence of these winds on Antarctica’s ice sheet has seen a decrease of 32 percent in ice melting.
“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 study co-author Charlie Zender, a professor of Earth System Science at UCI. “Surface melt leads to runoff and ice shelf hydrofracture that increase freshwater flow to oceans – causing sea level rise.”
Yet, Zender was quick to note the unique patterns of global warming exhibited in the Northern and Southern hemispheres. These differences are central to the varying ice melt trends in these regions.
In Greenland’s context, the sheer warmth means that even sunlight, in the absence of wind, can induce melting. This, when combined with the ten percent increase in wind-induced melting and the warmer atmospheric conditions, translates to a 34 percent surge in overall surface ice melting.
Zender attributes this to the effects of global warming on the North Atlantic Oscillation (NAO), an index of sea level pressure difference. This movement of NAO towards a positive phase has facilitated warm air to envelop Greenland and other northern areas.
On the other end of the spectrum, Antarctica has experienced about 15 percent less total surface melting since 2000. This downturn is attributed mainly to the 32 percent reduction in wind-induced melting in the Antarctic Peninsula. This area is especially concerning since two ice shelves here have already disintegrated.
The silver lining, as Zender argues, is the ongoing recovery of the Antarctic stratospheric ozone hole detected in the 1980s. This recovery process temporarily shields the region from further melting.
“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 explained.
“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.”
These findings will help increase the accuracy and reliability of Earth system models, offering deeper insights for climate scientists on the major problems our planet currently faces.
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