Many Holocene hydroclimate records show rainfall changes that vary with local orbital insolation. However, some tropical regions display rainfall evolution that differs from gradual precessional pacing, suggesting that direct rainfall forcing effects were predominantly driven by sea-surface temperature thresholds or inter-ocean temperature gradients. Here we present a 12,000 yr continuous U/Th-dated precipitation record from a Guatemalan speleothem showing that Central American rainfall increased within a 2000 yr period from a persistently dry state to an active convective regime at 9000 yr BP and has remained strong thereafter. Our data suggest that the Holocene evolution of Central American rainfall was driven by exceeding a temperature threshold in the nearby tropical oceans. The sensitivity of this region to slow changes in radiative forcing is thus strongly mediated by internal dynamics acting on much faster time scales.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the support of the touristic Grutas del Rey Marcos, in San Juan Chamelco, Department of Alta Verapaz, Guatemala, to whom we are indebted for their collaboration. H.C. acknowledges grant NSFC 41888101. M.L. acknowledges NSF facilities grant EAR-0521196. A.W. thanks the University Ca Foscari of Venice for hosting him while much of the paper was written. Thanks to Thay-Ling Moya-Perez for milling the samples at UPRM, Jon Baker who loaded most of the samples in the mass spec at UNLV, and Jose Santiago for his help during the field trip to obtain the GU-RM1 sample. F.S.R.P. acknowledges funding from the Swedish Research Council (FORAMS) as part of the Joint Programming Initiative on Climate and the Belmont Forum for the project “Palaeo-constraints on Monsoon Evolution and Dynamics (PACMEDY)” and the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC Grant RGPIN-2018-04981) and the Fonds de recherche du Québec—Nature et technologies (2020-NC-268559). The research was supported by National Science Foundation grant ATM 1003502.
© 2020, The Author(s).
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.