The analysis of polar ice cores has proven to be very instructive about past environmental conditions on the time scale of several climatic cycles, and recent drilling operations have provided information of great value for global change issues. The book presents the most recent data extracted from Greenland ice cores and surface experiments and compares them with former Antarctic results. It contains background articles, original contributions and group reports of interest to scientists, climatologists, atmospheric chemists, and glaciologists involved in global change research.