Fresh snow is better at reflecting the sunlight than old snow. Therefore, in a recent study, researchers cautioned that high pressure as snowfall decreased over Greenland is of concern. “The shape of snow changes and the snow particles grow over time,” researcher Gabriel Lewis said in a press release.
What can be described in many parts of the world as good weather poses problems with melting in Greenland. Photo gallery.
Researchers at Dartmouth College of America traveled 4,300 km on snowmobiles over Greenland in 2016 and 2017 to take a number of samples to find out why Greenland has become darker over the years, as satellite images reveal.
One theory is that snow contains dirt from pollution. But researchers were able to quickly dismiss it.
Alternatively, changing weather patterns over Greenland could be behind the change, which could affect the island’s thawing in several ways.
Continuous high pressure systems have become more and more popular in recent decades. It sometimes falls over the Greenland ice sheet for several weeks in a row, with warmer air and no cloud cover reflecting away sunlight.
The higher pressure systems, in turn, cause less new snowfall. The pure white snow also reflects the sunlight away, and its absence exposes the dark, ancient snow.
“When the snow ages, even for hours to a few days, the reflection decreases, which is why the new snow is so important,” says Eric Osterberg, one of the other researchers who conducted the study.
Snow changes shape over time. As they form in the atmosphere, they acquire pointed and luminous crystal shapes.
Because of the extreme cold in the atmosphere when it snows, Lewis says.
On Earth, snowflakes turn into larger grains, which are worse at reflecting sunlight.
High pressure systems have become more popular since the 1990s. Warmer air, less fresh snow and clear skies would be a triple blow to the ice sheet. The temperature on the ice sheet is 2.7 degrees higher than it was in 1982, which is probably the strongest temperature rise in the past 7,000 years.
“All of this is contributing to Greenland melting faster and faster,” says Osterberg.
Greenland is located on the North American continent, but politically it belongs to Europe as part of Denmark with a large degree of autonomy.
People have lived in Greenland for 5,000 years, and there are currently around 56,000 people.
Greenland is the largest island in the world, and nearly 80 percent of its area is covered by ice and glaciers. In winter, the temperature can drop to -50 degrees. In summer, the temperature rarely rises above 15 degrees.
Source: Scandinavian Cooperation