Geothermal evidence of very low glacial temperatures on a rim of the Fennoscandian ice sheet

Abstract

The mean ground temperature as low as -10°C and the existence of more than 500 m thick permafrost during the last glacial are apparent from the analysis of deep borehole temperature profiles in north-eastern Poland. The largest thickness of the permafrost and its survival deep into the Holocene was restricted to a region known for its low terrestrial heat flow, where the negative temperature gradient is observed in the uppermost 400 m. We have shown that the profiles are consistent with warming from the glacial mean of -10°C to the Holocene mean of +7°C 14 ka ago and to +8°C in the last 150 years. Copyright 2004 by the American Geophysical Union.