Palaeo-Climatic Studies on Ice Cores

Abstract

The most fascinating aspect of ice cores from the polar ice sheets is that they contain all kinds of fall-out from the atmosphere, i.e. precipitation, volcanic debris, airborne biological material, radioactive isotopes, cosmic particles etc. In addition, the air bubbles entrapped in the ice are samples of past atmospheres, so they contain information about the palaeo-atmosphere composition, including CO₂ content. In the Greenland ice sheet the annual snow and ice layers lie in a continuous sequence reaching as far back in time as to the deposition of the first snow layer that remained cold enough to avoid melting. In fact, any wide spread snowfall that has occurred in the last several hundred thousand years is still represented in the ice — nothing melts away. And yet, less and less is left per cm² of a given annual layer the older it gets, because it is continuously being streched, thus getting thinner and thinner as it approaches the bottom (Figure 1).