Geological records of changes in wind regime over south Greenland since the Medieval Warm Period: a tentative reconstruction

Published marine sediment core records and new information from terrestrial aeolian deposits from the surroundings of Igaliku Fjord, south Greenland, have been used for a tentative reconstruction of multi-decadal to centennial scale changes in the intensity of regional atmospheric circulation since the Medieval Warm Period. The marine data show that aeolian activity over southern Greenland was generally enhanced in the Medieval Warm Period between c. AD 900 and c. AD 1300. The preliminary data from the onshore aeolian deposits suggest that wind activity was strongest after AD 1000, reaching a peak close to AD 1300, after which atmospheric circulation intensity decreased. A comparison with the marine data shows that this decrease coincides with increased advection of Polar Water by the East Greenland Current at the beginning of the Little Ice Age. The aeolian sediment record suggests foehn wind activity displaying multi-decadal oscillations in the range of known north Atlantic climate oscillations. The intensity of erosional processes in south Greenland has previously often been attributed to farming activities initiated after AD 1000 by the Norse who disappeared a few hundred years later. Our findings suggest, however, that erosion in this area is mainly related to marked variations in wind strength.