HR: 1330h
AN: PP12A-0227    [PDF]
TI: The Response of Sea Surface Temperature to Past Global Climate Change at a California Margin Site
AU: * Greene, E E
EM: ErinGreene7@hotmail.com
AF: Ocean Sciences, University of California at Santa Cruz, Santa Cruz, CA 95064
AU: Dekens, P
EM: dekens@cats.ucsc.edu
AF: Ocean Sciences, University of California at Santa Cruz, Santa Cruz, CA 95064
AU: Ravelo, C
EM: acr@es.ucsc.edu
AF: Ocean Sciences, University of California at Santa Cruz, Santa Cruz, CA 95064
AU: Lyle, M
EM: mlyle@cgiss.boisestate.edu
AF: Center for Geophysical Investigation of the Shallow Subsurface, Boise State University, Boise, ID 83725
AU: Herbert, T
EM: Timothy_Herbert@brown.edu
AF: Geological Sciences, Brown University, Providence, RI 02912
AB: Measurements of alkenone unsaturation indices from marine sediments provide information about past sea surface temperature (SST) changes over the past several hundreds of thousands of years, and provide clues about the role of the surface ocean in global climate changes on long time scales. Sediment samples from Ocean Drilling Program (ODP) Site 1018, located at $36\deg$ 59.390'N, $123\deg$ 16.653'W on the California margin were analyzed to help understand of the role of the North Pacific subtropical circulation in global climate change, and the sensitivity of the subtropical system to solar forcing, and the natural variability of California coastal climate conditions. Today, the strength of coastal upwelling and of the California Current affect the SST at ODP Site 1018. Organics were extracted from sediment samples, and using gas chromatography di- and tri- unsaturated C37 alkenones were quantified for samples covering the last 150,000 years, which includes two glacial-interglacial transitions. Information from the first transition (20,000 - 0 yrs ago) yielded a change in SST that increased from 7.6 - $14.4\deg$C. Information from the second transition (140,000 - 107,000 yrs ago) yielded a change in SST that increased from 5.0 - $20.5\deg$C. The data from the first termination indicates that SST warming was related to change in the temperature of the California Current. The data from the second termination indicates that SST changed before the ice sheets began to melt suggesting that the California margin was part of an early response to solar forcing. A comparison to productivity indicators at ODP site 1018 show that SST is not related to the change in upwelling because productivity was higher when SST was warmer in the interglacial periods. It is important to compare our results to alkenone unsaturation index records from different sites along the California margin. Sites to the north and to the south of ODP Site 1018 yield somewhat different results that can be explained by local differences in coastal upwelling and circulation.
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting