Scientists map melting history of Greenland's ice sheet

Washington, September 17 (ANI): Researchers from the Niels Bohr Institute at the University of Copenhagen have mapped the history of the melting of the Greenland ice sheet.

Numerous drillings have been made through both Greenland's ice sheet and small ice caps near the coast.

By analyzing every single annual layer in the kilometres long ice cores, researchers can get detailed information about the climate of the past.

But now, the Danish researcher Bo Vinther and colleagues from the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen, in collaboration with researchers from Canada, France and Russia, have found an entirely new way of interpreting the information from the ice core drillings.

"Ice cores from different drillings show different climate histories. This could be because they were drilled at very different places on and near Greenland, but it could also be due to changes in the elevation of the ice sheet, because the elevation itself causes different temperatures," explained Bo Vinther about the theory.

Today, the ice sheet is more than three kilometres thick at its highest point and thinning out towards the coast.

Four of the drillings analyzed are from the central ice sheet, while two of the drillings are from small ice caps outside of the ice sheet itself.

By comparing the Oxygen-18 content in all of the annual layers from the four drillings through the ice sheet with the Oxygen-18 content of the same annual layers in the small ice caps, Bo Vinther has calculated the elevation course through 11,700 years.

Just after the ice age the elevation of the ice sheet rose slightly because when the climate transitions from ice age to warm age, there is a rapid increase in precipitation.

But at the same time, the areas lying near the coast begin to decrease in size, because the ice is melting at the edge.

When the ice melts at the edge, it slowly causes the entire ice sheet to 'collapse' and become lower.

The calculations show that in the course of about 3,000 years, the elevation changed and became up to 600 meters lower in the coastal areas.

But in the middle, it was a slow process, where the elevation decreased around 150 meters in the course of around 6,000 years.

It then stabilized.

The new results show the evolution of elevation of the ice sheet throughout 11,700 years and they show that the ice sheet is very sensitive to the temperature.

The results can be used to make new calculations for models predicting future consequences of climate changes. (ANI)