Dr Julian P Sachs

measurements provide estimates of sea surface temperatures, wind speeds and ocean productivity in the past. The focus is on the last four ice ages, or 450,000 years. I am particualrly interested in documenting and understanding the causes of abrupt climate change, and the mechanisms by which insolation variations, induced by periodic variations in earth’s orbital geometry, cause climate to change. Close collaborations with meteorologists and physical oceanographers here in the MIT Dept of Earth, Atmospheric and Planetary Sciences are underway to understand and test the mechanisms underlying the climate change we observe in geologic record. Researchers interested in climate modeling, as well as in paleoclimate measurements, are therefore encouraged to apply. Central to achieving our goals is the refinement and development of paleoclimate proxies and absolute and relative chronologies of sediment and ice cores. Organic geochemical techniques for precisely synchronizing sediment and ice cores using organic constituents derived from a common source (terrestrial vegetation) are under development. In addition, a radiocarbon dating technique for opal-rich sediments with low abundances of foraminifera (e.g., Southern Ocean, North Pacific, lacustrine) is being developed.