Collaborative Research: Hydrological Variability During the Last Millennium from High Resolution Proxies

DESCRIPTION: The overall goal of this project is to characterize Caribbean hydrologic variability during the last millennium using a terrestrial network of speleothems, and Cariaco Basin data. The project involves the collection, dating and documenting the variations in proxy information derived from new speleothem records and comparing and matching them to existing records so that a robust picture of the regional variability over several centuries can be determined. Parallel to this line of research the project aimes to establish the link between the regional variations and large-scale indices, such as available information on sea surface temperature (SST) variations in the Pacific and the Atlantic, to determine the global linkages and causes of the regional variability and to put the results in the perspective of the instrumental record.

OUTCOMES: We obtained 22 speleothems chosen from different parts of Mesoamerica some of which contain records of annual or near-annual fidelity of the last 1,000-10,000 years. Results of our analyses of geochemical proxies show multi-decade changes in hydrology forced by ocean modes of variability (Winter et al., 2011) as well as persistent drying events of Mesoamerica driven by volcanic and solar forcing ((Winter et al., 2015). Furthermore a speleothem from Puerto Rico recorded strong hydrological changes ca. 3.7 thousand years ago that forced humans to develop adaptation strategies (Rivera-Collazo et al., 2015). We found evidence in speleothems from Puerto Rico and Venezuela for a Caribbean wide rainfall decrease 8.2 thousand years ago, corresponding to a well-documented, northern hemisphere abrupt cooling event recorded in Greenland ice cores (Rolf Vieten, Ph.D. thesis).