HR: 16:15h
AN: PP34A-02 INVITED    [Abstracts]
TI: An Eight-Century High-Resolution Paleoclimate Record From the Cariaco Basin: Baseline Variability and the 20^th Century
AU: * Black, D E
EM: David.Black@stonybrook.edu
AF: Stony Brook University, School of Marine and Atmospheric Sciences, Stony Brook, NY 11794, United States
AU: Thunell, R C
EM: thunell@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208, United States
AU: Kaplan, A
EM: alexeyk@ldeo.columbia.edu
AF: Columbia University, Lamont-Doherty Earth Observatory, Pallisades, NY 10964, United States
AU: Tappa, E J
EM: tappa@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208, United States
AU: Peterson, L C
EM: peterson@rsmas.miami.edu
AF: University of Miami, Rosenstiel School of Marine and Atmospheric Science, Miami, FL 33149, United States
AB: The Cariaco Basin, Venezuela is well-positioned to record a detailed history of surface ocean changes along the southern margin of the Caribbean and the tropical Atlantic. Varved, high deposition rate sediments deposited under anoxic conditions and an abundance of well-preserved microfossils result in one of the few marine records capable of preserving evidence of interannual- to decadal-scale climate variability in the tropical Atlantic. Here we present Mg/Ca and stable oxygen isotope data with sub-decadal resolution derived from sediments deposited over the last 800 years. Mg/Ca measured on the planktic foraminifer Globigerina bulloides from a Cariaco Basin sediment core strongly correlates with spring (March-May) instrumental SSTs between AD 1870 and 1990. The long-term record displays a surprising amount of variability for a tropical location. The temperature swings are not necessarily related to local upwelling variability, but instead represent wider conditions in the Caribbean and western tropical Atlantic. The Mg/Ca-SST record also captures the decadal and multidecadal variability observed in global land and sea surface temperature anomalies, and correlates with Atlantic tropical storm and hurricane frequency over the late-19^th and 20^th centuries. On average, 20^th century temperatures are not the warmest in the entire record, but they do show the largest increase in magnitude and fastest rate of SST change over the last eight hundred years. Stable oxygen isotope data also correlate well with instrumental SSTs, but not over the full instrumental record. Poor correlations with early instrumental SST data suggest a salinity overprint. However, reconstructing δ- water variability using combined Mg/Ca and δ¹⁸O data is not straightforward as the δ- water/salinity relationship varies seasonally in the Cariaco Basin. Comparisons with percent titanium data suggest intervals of both local and regional surface salinity changes over the length of the record.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting