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Incoherency in Central American hydroclimate proxy records spanning the last millennium
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  • Jonathan Obrist-Farner,
  • Byron A. Steinman,
  • Nathan D. Stansell,
  • Jeremy Maurer
Jonathan Obrist-Farner
Missouri S&T

Corresponding Author:obristj@mst.edu

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Byron A. Steinman
University of Minnesota, Duluth
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Nathan D. Stansell
Northern Illinois University
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Jeremy Maurer
Missouri University of Science and Technology
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Continued global warming is expected to result in drying of Central America, with projections suggesting a decrease in precipitation. Poor hindcasting of precipitation, however, due in part to spatial and temporal limitations in instrumental data, subjects these projections to considerable uncertainty. Paleoclimate proxy data are therefore critical for understanding regional climate responses during times of global climate reorganization. Here we present two lake-sediment based records of precipitation variability in Guatemala along with a synthesis of Central American hydroclimate records spanning the last millennium (800-2000 CE). The synthesis reveals that regional climate responses have been strikingly heterogeneous, even over relatively short distances. Our analysis further suggests that shifts in the mean position of the Intertropical Convergence Zone, which have been invoked by numerous studies to explain variability in Central American and circum-Caribbean proxy records, cannot alone explain the observed pattern of hydroclimate variability. Instead, interactions between several ocean-atmosphere processes and their disparate influences across variable topography have resulted in complex precipitation responses. These complexities highlight the difficulty of reconstructing past precipitation changes across Central America and point to the need for additional paleo-record development and analysis before the relationships between external forcing and hydroclimate change can be robustly determined. Such efforts should help anchor model-based predictions of future responses to continued global warming.