P2C2: North American Megadrought: Atmosphere-Ocean Forcing and Landscape Response from the Medieval Period to the Near-Term Greenhouse Future

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Funding is provided to investigate whether landscape and vegetation feedbacks played a role in creating the severity and persistence of Medieval megadroughts and if these feedbacks might also impact future anthropogenic-induced aridification. Specifically, the researchers will: 1) create new marine proxy-based reconstructions of tropical sea surface temperatures (SSTs) for the Medieval period and use these to force atmosphere models in an attempt to simulate the megadroughts. The resulting modeled climatology will then be used to force vegetation models to estimate vegetation change during the megadroughts. These estimates will be used to develop additional atmosphere model simulations (with an interactive dust module) that combine the impact of SSTs, removal of vegetation and expanded dust sources and aerosol loading. Other atmosphere model simulations will be forced with altered vegetation and dust source boundary conditions as estimated from paleoenvironmental data; 2) force vegetation models with projections of future climate (from the Intergovernmental Panel on Climate Change Assessment Report 4) to determine changes in vegetation and dust sources that will be used as boundary conditions in additional simulations of future climate change; and 3) work to develop a fully coupled land surface-vegetation-dust module for inclusion in the Goddard Institute for Space Studies (GISS) model for use in additional simulations of SST-forced Medieval megadroughts and of future climate.The broader impacts involve supporting undergraduate and graduate students, supporting a new researcher, and contributing to the understanding of climate-related drought. This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).