An investigation of rapid warm transitions during MIS2 and MIS3 using Greenland ice-core data and the CLIMBER-2 model 

Annals of Glaciology, 35, p. 398-402, 2002 

I.A. Mogensen and S.J. Johnsen
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
A. Ganopolski and S. Rahmstorf
Potsdam Institute for Climate Impact Research, Telgrafenberg C4, P.O. Box 601203, D-14472 Potsdam, Germany.

ABSTRACT.
In the search for a better understanding of the dominant mechanisms of the Earth's climate system, we present a study of rapid warm-climate transitions to Dansgaard-Oeschger events as seen in the ice cores from the Greenland ice sheet. We present a continuous δ¹⁸O record from the Greenland Icecore Project (GRIP) core with a resolution of 5 years until 50 kyr BP and of 20 years until 100 kyr BP. These data are compared with other high-resolution records, i.e. the Greenland Ice Sheet Project II (GISP2) chemistry record (25 years until 50 kyr BP) and the GRIP Ca²⁺ record (3 years until 100 kyr BP). All records have been transformed to the GISP2 Meese/Sowers time-scale. The high-resolution records are separated into interstadials and stadials, defined by the GRIP and GISP2 δ¹⁸O records. We examine in detail the transition into the Dansgaard-Oeschger events, and propose a scenario for the changes that occur in the different ice-core records during the approximately 50 years the transition takes. The main difference from previous studies is the much higher-resolution datasets available until 50 kyr BP; previous high-resolution studies by Taylor and others (1997) have focused on only the Younger Dryas/Preboreal transition. The data are compared to model simulations of the Dansgaard-Oeschger events performed with the CLIMBER-2 model of intermediate complexity (Petoukhov and others, 1998; Ganopolski and Rahmstorf, 2001).