Washington, Feb 21 (ANI): A new study by researchers from Lund University in Sweden has determined that permafrost is thawing in northern Sweden, because of warmer summers and more winter precipitation.
According to a report in ENN (Environmental News Network), the study was undertaken by physical geographer Margareta Johansson at Lund University, who studied lowland permafrost in peat mires surrounding Abisko.
Permafrost is ground that is frozen year round at least two years in a row. North of the Arctic Circle permafrost is common due to the cold climate.
Johansson said that permafrost is being affected by climate changes.
"At one of our sites, permafrost has completely disappeared from the greater part of the mire during the last decade," she said.
In areas where permafrost is thawing, the ground becomes unstable and can collapse. This can be a local and regional problem in areas with cities and infrastructure.
Moreover, the thaw can cause increased emissions of the greenhouse gases carbon dioxide and methane from the ground.
Roughly 25 percent of all land surface in the northern hemisphere are underlain by permafrost.
The thawing of permafrost that occurs today is likely to continue, in Johansson's view.
She regards it as probable that there will be no permafrost in lowland areas around Abisko in 50 years.
"With the present climate it is likely that the changes seen in permafrost in the Abisko area will also occur in other areas, and my study can therefore provide a basis for studies in other geographic areas that are next in line," she said.
Johansson's research shows that the permafrost in the Abisko area is thawing both from above and from below.
From above, it is thawing primarily because the summers have become warmer and because the snow cover has become thicker in winter.
A thicker snow layer acts as an insulating blanket, which means that the ground does not get as cold as it would under a thinner layer of snow.
From below, the permafrost is thawing probably as a result of greater mobility in the groundwater.
According to Johansson, the annual precipitation of both rain and snow has increased dramatically during the last decade.
More rain and more melted snow create more movement down in the groundwater, which thaws the permafrost. (ANI)