The melting of ice sheets in Greenland is limited by a natural process, according to a new study. However, this state may not last long as global warming continues to raise temperatures around the world.
In Greenland, ice sheets near coastal areas have been observed melting at a rapid pace, but inner regions have shown much slower, or even negligible, losses. Around 40 percent of the ice sheet on the island nation have shown little to no loss of coverage. This fact has driven environmentalists to try to explain what may be protecting the frozen landscape.
Precipitation is normally expected to become more common as temperatures rise. However, little additional moisture has fallen in the region over the last several years, investigators report.
A layer of air was found to form during winter months, acting as a blanket, lowering evaporation from the ground, and reducing precipitation in the region. Near the surface, this air mass is cold and stable. But just over 300 feet above the ground, the air becomes warmer and average wind speeds increase.
The ice sheet, measuring 2.2 miles in depth, can often be tough to observe, due to snowfall and low-lying clouds.
"We decided to investigate whether you could find the answer in the atmosphere above the ice sheet by measuring the atmospheric processes directly. We therefore took measurements of the water vapour in the atmosphere for three years," said Hans Christian Steen-Larsen from the Centre for Ice and Climate at the Niels Bohr Institute, managed by the University of Copenhagen.
Above this boundary, water in the air can form fog, but the phenomenon does not grow thick enough to fall to the ground in the form of precipitation. However, it does coat the ground in new layers of ice, reducing evaporation, investigators concluded.
Researchers also examined ice cores — samples of the frozen ground cover that can reveal climatic conditions going back tens of thousands of years. Analysis of ice samples from the last 11,000 years showed that increased precipitation did not always follow periods of warming in the region, researchers determined. This finding lends credence to the idea that this air layer is, temporarily, reducing loss of the inland Greenland ice shelves.
Analysis of the forces reducing the loss of ice and precipitation was profiled in the journal Science Advances.
Photo: Christopher Cox | Flickr
