Climate during glaciation and deglaciation identified through chemical tracers in ice-cores

Presented here are the results and interpretations of an analysis of 8 chemical species obtained from the Greenland Ice Sheet Project 2 (GISP2) [Mayewski et al 1994; Mayewski et al 1993] ice-core, covering the period 41-0 Kyr BP. A reduction of the system to three distinct base vectors describing the 8 dimensional species space is possible. These are believed to represent the different sources of aerosols that have been transported via the atmosphere, and precipitated onto the Greenland ice-sheet. Physical reasoning suggests that these are mainly a signature of (1) an ocean source, (2) continental land and exposed continental shelves, and (3) biochemical land sources. Correlations between the resulting time series, describing the temporal contributions from the 3 source areas, reveal five distinct periods over the 41 Kyrs record, each differing dramatically in the contributed abundance of chemical species from the sources. Mechanisms are proposed to explain differences in the climate dynamics over the five periods, with interpretations leading to new information regarding paleo sea level and glacial extent. Such findings are important for reconstructing the climate prior to the Last Glacial Maximum (LGM).