Putting the West Antarctic Ice Sheet into context

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1042728/DentonThis award supports a project to develop new insights into the cause and pattern of events during the last glacial termination in South America and Antarctica. One emerging view is that a warming Southern Ocean (SO), driven by a chain of events initiated in the Northern Hemisphere (NH) and tied to the interhemispheric climate seesaw of the last termination, was the underlying mechanism that drove the West Antarctic ice sheet (WAIS) from its Late Glacial Maximum (LGM) position back to present-day grounding lines. This ocean thermal forcing would have impacted WAIS by accelerating basal melt rates on fringing floating ice shelves and tongues. The validity of such a proposition can be examined from detailed chronologies of ice retreat at a variety of middle to high latitude sites. From such chronologies, it can be determined whether or not the intervals of ice recession form a pattern that fits the timing of warming pulses known to have occurred in the SO during the termination. The intellectual merit of this project is that it will test the proposition that warming pulses in the SO, driven by NH stadials, are the key events that culminated in recession of WAIS to its present-day configuration, setting up the possibility of irreversible collapse. This test is based on placing into a global context the timing and structure of glacial recession along a transect from the southernmost Andes to the Ross Embayment. This project will examine the middle of the transect, by establishing the chronology of ice recession following the LGM in southernmost South America and on the northern Antarctic Peninsula. Because of the abundance of datable terrestrial organic material in association with glacial deposits ?the most rapid progress will be made by starting in southernmost South America. Specifically, cores will be collected from numerous bogs located between the LGM limit and present-day ice in Cordillera Darwin and on Isla Hoste, and use 14C dates of basal organic remains to develop a chronology for ice recession. The broader impacts of this work include a commitment to education and outreach. This work will educate a graduate student and material from this grant will be used in college courses, as well as in presentations to elementary and middle schools and to senior communities. This proposal does not require field work in the Antarctic.