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Inter-Hemispheric Climate Teleconnections in response to Massive Iceberg Discharge in the North Atlantic


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Changes in the climate of one part of the world can often be associated with changes in another part of the world. For example, on time scales of hundreds of years, coarse scale proxies indicate that the temperature of the North Atlantic region of the globe may change while the temperature of the South Atlantic region changes with the opposite sign. Models of this "bipolar seesaw" invoke the long-distance transmission (teleconnection) of information through the atmosphere or the ocean. This work will use ice core records from Greenland and Antarctica to investigate the relative roles of oceanic and atmospheric teleconnections in coupling both hemispheres during so-called "Heinrich events" - massive discharges of icebergs into the North Atlantic that happened repeatedly during the last ice age. The work will help climate scientists understand dynamical changes that occur on times scales that are much longer than observational records from weather stations. The project will also contribute to development of the STEM workforce. It will provide support for an early-career scientist during the formative years of his career. It will provide support for one or more undergraduate laboratory technicians and entrain undergraduates, supported through other sources, into the research. It will include STEM outreach to local middle school students and a teacher training program. It will result in a series of Wikipedia entries concerning paleoclimate. As an ancillary benefit, it will improve the chronology of the Greenland ice core to be studied. This will allow greater synchronization of paleoclimate records between the two poles and facilitate progress in the study of past climates. This work will generate high-resolution, high-precision records of Greenland (GISP2) ice core methane, 15N/14N ratio of molecular nitrogen, and air content for the period of 14-51 ka before present, to investigate a number of important paleoclimatic questions with a special focus on Heinrich stadials. The work is organized under four overarching goals: (1) to detect the impact of Heinrich events on Greenland climate, and use the timing of these events relative to observed rapid Antarctic warming to investigate whether the mode of interhemispheric climate coupling during these events is via an atmospheric or an oceanic teleconnection; (2) to achieve interpolar methane synchronization of the GISP2 and WAIS Divide ice cores at unprecedented centennial-scale resolution, with applications in studying interhemispheric climate teleconnections and ice core dating.; (3) to provide the most accurate Greenland temperature reconstruction to date by combining nitrogen isotope data with independent delta-age estimates derived from the methane synchronization; and (4) to improve understanding of air content as a proxy for ice sheet elevation, and investigate origin of millennial-scale air content variations during Dansgaard-Oeschger events not previously described in the literature. This project exploits the unique scientific possibilities arising from the recent centimeter-scale WAIS Divide methane record to enhance the interpretation of Greenland ice cores and inter-polar climate connectivity