The NorthGRIP deep drilling programmeAnnals of Glaciology, 35, p. 1-4, 2002
D. Dahl-Jensen, N.S. Gundestrup, H. Miller, O. Watanabe, S.J. Johnsen, J.P. Steffensen, H.B. Clausen, A. Svensson and L.B. Larsen
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
Alfred-Wegener-Institut für Polar- und Meerforschung, Postfach 120161, D-27570 Bremerhaven, Germany.
National Institute of Polar Research, Kaga 1-9-10, Itabashi-ku, Tokyo 173-8515, Japan.
The North Greenland Icecore Project (NorthGRIP) was initiated in 1995 as a joint international programme involving Denmark, Germany, Japan, Belgium, Sweden, Iceland, the U.S.A., France and Switzerland. The main goal was to obtain undisturbed high-resolution information about the Eemian climate period (115-130 kyr BP). The records from the Greenland Icecore Project (GRIP) and Greenland Ice Sheet Project 2 (GISP2) in central Greenland are different and disturbed down in the ice covering this period. Internal radio-echo sounding layers show that NorthGRIP, placed 325 km north-northwest of GRIP at the Summit of the Greenland ice sheet, is located on a gently sloping ice ridge with very flat bedrock and internal layers found so high that an undisturbed Eemian record is possible. Internal layers much farther above bedrock than their apparent counterparts at GRIP suggest that conditions are favourable for recovery of an undisturbed Eemian record. So far, a 1351 m deep ice core (NorthGRIP 1) and a 3001 m deep ice core (NorthGRIP 2) have been recovered. The ice thickness is expected to be 3080 m, and the ice temperature at 3001 m is -5.6oC, so we expect basal melting at the bedrock. Most of the Eemian ice will be melted away, leaving only the last part and the transition between the Eem and the Last Glacial Period. At 3001 m the age of the ice is 110 kyr BP and the annual layers are of the order 1 cm. With modern methods the annual layers can be resolved, resulting in detailed information on the decline of the warm Eemian period into the Last Glacial Period.