Record of the 17O-excess of H2O in the WAIS Ice Core

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Steig/0837990This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This award supports a project to obtain a ~100,000-year record of 17O-excess from the WAIS Divide ice core, currently being drilled in West Antarctica. To date, a 17O-excess record has been obtained only on one ice core ? from Vostok. WAIS Divide is appealing for comparison with Vostok because it is located in a very different moisture transport regime, and will be influenced by potentially quite different changes in sea ice and atmospheric circulation. The intellectual merit of the work is that 17O-excess, obtained from the high-precision measurement of both 18O/16O and 17O/16O in ice core H2O, provides information highly complementary to deuterium excess which is used to provide useful insight into past climate conditions because of its dependence on evaporative conditions at the ocean surface source regions where polar precipitation is ultimately derived. Unlike deuterium excess, 17O-excess is independent of source temperature, and is only weakly influenced by fractionation during transport from source to ice sheet. 17O-excess therefore offers great potential, in combination with traditional measurements, as a powerful new tool for evaluating climate conditions in the past. In particular, it provides the opportunity to disentangle the effects of source humidity, wind speed, and temperature, local site temperature and fractionation during transport, on ice core water isotope records. The broader impacts of the work are that it contributes to the development of infrastructure and expertise needed both for glaciology and paleoclimatology, as well as for other research areas. A graduate student will work on both the method development and the analysis and interpretation of the ice core profile, providing plenty of material for a well-rounded and novel Ph.D. thesis.