HR: 12:05h
AN: PP32A-08    [Abstracts]
TI: Warmer Tropics During the mid Pliocene: Evidence From Alkenone Paleothermometry and a Fully Coupled Ocean-Atmosphere GCM
AU: * Haywood, A M
EM: ahay@bas.ac.uk
AF: British Antarctic Survey, Geological Sciences Division, High Cross, Madingley Road , Cambridge, Cam CB30ET United Kingdom
AU: Dekens, P
EM: dekens@cats.ucsc.edu
AF: University of California Santa Cruz, Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA 95064 United States
AU: Ravelo, A C
EM: acr@es.ucsc.edu
AF: University of California Santa Cruz, Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA 95064 United States
AU: Williams, M
EM: mwilli@bas.ac.uk
AF: British Antarctic Survey, Geological Sciences Division, High Cross, Madingley Road , Cambridge, Cam CB30ET United Kingdom
AB: Traditional reconstructions of sea-surface temperatures (SSTs) produced by the PRISM Group (Pliocene Research Interpretations and Synoptic Mapping) indicate that mid Pliocene surface ocean temperatures were unchanged relative to modern at the tropics and low-latitudes and significantly warmer at higher latitudes, particularly in the North Atlantic. This change in the latitudinal pattern of SSTs has been attributed to enhanced meridional ocean heat transport generated by more vigorous surface ocean gyres and/or thermohaline circulation. This study assesses established SST reconstructions for the mid Pliocene through the application of combined data/modeling techniques. New SST estimates were derived using alkenone paleothermometry at three tropical/subtropical Pacific sites. Published alkenone SST estimates for the Atlantic Ocean were also utilized. The new SST data were combined with predicted SSTs derived from a fully-coupled mid Pliocene ocean-atmosphere general circulation model. Significant differences are noted between absolute PRISM, alkenone and model-predicted SSTs. These differences are generated by errors in the PRISM and alkenone paleothermometry estimates as well as limitations of the climate model itself. However, alkenone and model-based SST estimates are consistent in that both predict a pattern of SST warming during the mid Pliocene in tropical and low-latitude regions, which contrasts with PRISM's estimates of unchanged SST in these regions. The latitudinal pattern of SSTs, produced by alkenone estimates and modeling, is not characteristic of that produced by enhanced meridional ocean heat transport or thermohaline circulation. Instead the pattern is similar to that which might be expected as a result of higher concentrations of atmospheric CO2, which would act to warm the oceans globally.
DE: 9604 Cenozoic
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting