EAR-PF: Reconstructing late Holocene hydroclimatic variability in western Central America using multi-proxy analyses of lacustrine sediments

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Dr. Derek Gibson has been awarded an NSF EAR Postdoctoral Fellowship to carry out research and education plans at Missouri University of Science and Technology under the mentorship of Dr. Jonathan Obrist-Farmer. Hydroclimate extremes, particularly droughts, have resulted in an unprecedented increase in climate refugees from Central America over the past decade, creating a humanitarian, economic, and national security crisis. Current climate models predict that Central American precipitation will further decrease by the end of the century. However, the models used to predict such changes rely on records of past climate change and, at present, regional data that reflect how Central American precipitation changed in the past are sparse. This project will use sediment cores collected from Guatemala and southern Mexico to produce evidence of past changes in Central American precipitation that spans the past 2,000 years. In turn, these new records will improve current predictive models of Central American precipitation, which is critical to building a climate-resilient future in Central America and reducing the extent of climate-driven human migration over the upcoming decades. In addition to producing new climate data, K-12 partnerships will extend the impact of this research by educating the next generation of scientists on the mechanisms and impacts of climate change. Educational activities and international collaborations will involve students from elementary to graduate school and provide opportunities for historically underserved students to contribute to solving one of the major climate science questions of the 21st century.Predictable precipitation patterns are critical to the food security and economic stability of Central America. However, inter-model heterogeneity among current climate models, due in part to a paucity of high-resolution and local-scale paleoclimate records that span the late Holocene, make reliable projections of future precipitation difficult. The proposed research will utilize sediment cores from six watersheds located across Guatemala and the Yucatán Peninsula in order to produce multi-proxy reconstructions of local-scale hydroclimatic variability within the context of the synoptic-scale climate changes that occurred during the Medieval Climate Anomaly, Little Ice Age, and Current Warm Period. The proposed field sites are situated such that sediment cores collected from these sites can be used to investigate variability through time in the relative influences of the Inter-tropical Convergence Zone, Caribbean Low-Level Jet, El Niño Southern Oscillation, and topography. Specifically, stratigraphic variability of δ2H in leaf-wax long chain (n-C27, n-C29, n-C31) n-alkanes preserved in the sediment cores will be used as a proxy for regional hydroclimatic variability, while the δ2H of short chain (n-C21, n C23) n-alkanes will be used to reconstruct precipitation/evaporation balance at the local (water column to watershed) scale. These data will be a critical component of predictive models used in the Central American climate resilience and adaptation plans that must be implemented before climate-driven human migration leads to further suffering.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.