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

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 transitions 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).