PROXY COMPARISON OF LATIN AMERICAN HYDROCLIMATE VARIABILITY OVER THE LAST 800 YEARS

Proxies including speleothem calcite and lake and marine sediments sourced from Vieques (Puerto Rico), Cariaco Basin (Venezuela) and Brazil were compared with an 800 year stable isotope record obtained from a Puerto Rican speleothem (PDR-1) and statistically analyzed. As expected, a positive correlation is observed between PDR-1 calcite and a lake sediment record from Vieques, Puerto Rico since 1850. When comparing the Brazilian and Puerto Rican speleothem stable isotope records, decoupling is observed from approximately 1250 – 1800 AD. Comparison between Cariaco Basin titanium concentrations, PDR-1 stable isotopes and Caribbean salinity shows a positive correlation from approximately 1400 – 1800 AD. A common link between these correlations is the mean position of the ITCZ over centennial time scales. This explains the decoupling observed between the northern and southern hemispheres, as well as the coupling observed in the Caribbean region. After 1800 AD, the Puerto Rican and Brazilian speleothem records become coupled. Instrumental data suggests that the ITCZ has been moving southward over the past hundred years and implies an alternate mechanism for the coupling observed between Brazil and the Caribbean region. Further research is necessary to explain this modern change in hydroclimate variability.