Modeling the Glacial Evolution on Antarctica and the Paleogene Transition From a "Greenhouse" to "Icehouse" World

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The glaciation of East Antarctica and the associated shift to cold condition over high southern latitudes represents the most fundamental reorganization of the global climate-ocean system in the Cenozoic. Determining the mechanisms responsible for the nucleation, development, and periodic fluctuations of the Antarctic ice sheet is important to our understanding of the global climate system and future climatic change. The Cenozoic cooling trend from the warm "greenhouse" climate mode of the Early Eocene, to the "ice house" world of today, has long been recognized in paleontologic, isotopic, and sedimentologic evidence. This award supports designed to answer these question: 1) what long-term paleoenvironmental changes led to the growth of limited Antarctic ice during the mid-Late Eocene and 2) what triggered the rapid growth of the East Antarctic ice sheet in the earliest Oligocene (-33.7 ma). A comprehensive investigation of Late Eocene/Early Oligocene climate echoing, designed to isolate the relative role of possible climate forcing mechanisms and feedbacks in the transition from a "greenhouse" to "icehouse" world, will use the GENESIS Version 2.0 Global Climate Model, interactivity coupled to a predictive vegetation model (IBIS) and asynchronously coupled to a new high resolution dynamical ice sheet model specifically designed for GCM investigations of ice-sheet initiation and development. A systematic series of sensitivity tests will assess the role of atmospheric CO2, orbital parameter, atmosphere-vegetation feedbacks, paleogeography, and ocean heat transport in the initiation and growth of glacial ice on Antarctica.