The 18o/16o ratio of the ice in a core through the central part of the Greenland ice sheet provides a uniquely detailed record of paleoenvironmental conditions that may extend back as far as 200,000 years. This project will study the 18o/16o ratio to determine the characteristics of the major global climate cycles and the cause and effect relationships between the various environmental parameters, such as temperature, concentration of CO2 and CH4, dustiness, and cation/anion concentration, that change with climate. A better definition of the processes that determine climate change will provide better predictions of future climate change. The location of intervals of major and/or rapid climate change will be the focus of detailed multiparameter studies, This study will provide a preliminary isotope stratigraphy of the core. The 18o/16o research is part of the multiparameter multi-investigator GISP II project. A special collaboration with J.W.C. White, University of Colorado, will provide a record of deuterium excess (d").