Chilling discoveries

The changing thickness of Greenland’s ice sheet can be mapped back 11,700 years, all the way to the beginning of the current warm period, thanks to research from the University of Copenhagen and collaborators.

By analysing every single annual layer in the kilometre-long ice cores researchers can get detailed information about the climate of the past. But the researchers from the 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” explains Bo Vinther about the theory.

In the new method, researchers compare levels of an oxygen isotope from four drillings through the ice sheet with the levels of the same isotope in small coastal ice caps.

The research shows that the elevation of the ice sheet rose slightly after the Ice Age due to an increase in precipitation in the transition into the present Warm Age. This rise, however, was counteracted with a decrease in the size near the coast of the sheet caused by melting ice on its edges. This melting causes the entire ice sheet to collapse and levels to lower.

The results, published in the scientific journal Nature, can be used to make improved models for predicting the consequences of climate change.

uni-avis@adm.ku.dk