Earth's heat loss causing ice sheet to slide towards sea
London: Heat lost from the Earth's interior is causing glaciers to slide from Greenland's ice sheet towards the sea, a study has found.
Researchers from the Aarhus University in Denmark and the Greenland Institute of Natural Resources showed for the first time that the deep bottom water of the north-eastern Greenland fjords is being warmed up by heat gradually lost from the Earth's interior.
This heat loss triggers the sliding of glaciers from the ice sheet towards the sea.
"North-East Greenland has several hot springs where the water becomes up to 60 degree warm and, like Iceland, the area has abundant underground geothermal activity," said Soren Rysgaard, who headed the study published in the journal Scientific Reports.
For more than ten years, researchers have measured the temperature and salinity in the fjord Young Sound, located at Daneborg, north of Scoresbysund, which has many hot springs, and south of the glacier Nioghalvfjerdsfjorden, which melts rapidly and is connected to the North-East Greenland Ice Stream (NEGIS).
By focusing on an isolated basin in the fjord with a depth range between 200 and 340 m, the researchers have measured how the deep water is heated over a ten-year period.
Based on the extensive data, researchers have estimated that the loss of heat from the Earth's interior to the fjord is about 100 megawatt per square metre.
This corresponds to a two megawatt wind turbine sending electricity to a large heater at the bottom of the fjord all year round.
It is not easy to measure the geothermal heat flux - heat emanating from the Earth's interior - below a glacier, but within the area there are several large glaciers connected directly to the ice sheet.
If the Earth releases heat to a fjord, heat also seeps up to the bottom part of the glaciers. This means that the glaciers melt from below and thus slide more easily over the terrain on which they sit when moving to the sea.
"It is a combination of higher temperatures in the air and the sea, precipitation from above, local dynamics of the ice sheet and heat loss from the Earth's interior that determines the mass loss from the Greenland ice sheet," said Rysgaard.
"There is no doubt that the heat from the Earth's interior affects the movement of the ice, and we expect that a similar heat seepage takes place below a major part of the ice cap in the north-eastern corner of Greenland," he said.