OCE-RIG: Variability in Atlantic Meridional Overturning Circulation (AMOC) strength and hydrological conditions in the central Sahara/Sahel during the Pliocene-Pleistocene

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In this project, the principal investigator will examine past AMOC variability and hydrology in the Sahel using a multi-proxy geochemical approach.Changes in the strength of the Atlantic meridional overturning circulation (AMOC) are known to have a major influence on global climate with the areas around the North Atlantic, including Europe, North America, and northwest Africa. It is predicted that the AMOC may slow down during the 21st century, based on current model simulations from the Intergovernmental Panel on Climate Change. Therefore, it is important to develop a better understanding of past AMOC variability and its impacts on ocean and continental climates as well as to further develop and refine methods for fingerprinting past AMOC variability. A distinctive feature of AMOC slowdown in the tropical North Atlantic is surface cooling accompanied by shallow subsurface (30 m) warming. A recent study of the tropical N Atlantic demonstrated that organic geochemical temperature proxies can be used to simultaneously reconstruct surface and subsurface water temperatures. Through this research effort, the AMOC variability and hydrological conditions in the Sahel will be reconstructed by using a multi-proxy geochemical approach to examine sediments from ODP Hole 660A. This project is designed to test the hypothesis that the characteristic AMOC signature of anti-correlated variation between surface and subsurface water temperatures in the tropical N Atlantic also existed on longer multi-millennial to million-year timescales. This research will provide new records of sea surface temperature (SST), subsurface temperature, and continental vegetation and hydrology during the Pliocene-Pleistocene, which will be used to examine relationships between AMOC and continental hydrology. A particular focus is on the mid-Pliocene warm period, an analog for future warming on Earth, and during the onset and intensification of Northern Hemisphere glaciations in the late Pliocene, when major steps in mammalian and hominin evolution occurred. A new Plio-Pleistocene SST record generated by this work will be used to examine the evolution of zonal and latitudinal SST gradients. Education is an important part of the broader impacts of this project. The educational aspects of this proposal consist of training a graduate student, two undergraduates, and six high school science teachers. The proposed activities will introduce high school students to the exciting subject of ocean sciences and provide them with information on career opportunities in this field. In an effort to increase awareness of the ocean sciences to under-represented groups, as well as overall participation in the ocean sciences, science teachers will be recruited from high schools lacking Earth Sciences curriculum. The high school teachers will visit the University of Massachusetts-Amherst during the summer and work with the PI and graduate student to produce classroom activities that can be incorporated into high school chemistry, biology and physics courses. Subsequently, the PI, undergraduates and graduate student will visit the home high school of each teacher during the academic year to inform students about career opportunities in the ocean sciences. This project is supported under the NSF Ocean Sciences Research Initiation Grant (OCE-RIG) program, with goals to support novel research by early career scientists and increase the diversity of the U.S. ocean sciences workforce and research community. With OCE-RIG support, this project will enable a promising early career researcher to establish themselves in an independent research career related to ocean sciences and broaden participation of under-represented groups in the ocean sciences.