Western equatorial Pacific climate variability from restricted basins: Century scale changes in Kau Bay to glacial-interglacial changes in the Sulu Sea.

摘要

The surface ocean in the western equatorial Pacific contains some of the warmest water on the planet in the western Pacific warm pool (WPWP). Changes in the size and scope of the warm pool have a significant impact on global climate. With the concern of changes in the extent of this body of water as a result of anthropomorphic changes in atmospheric composition, it is vital to investigate prior changes to the WPWP, the causes of such changes, and resultant effects. For my dissertation, I used several proxies to analyze sediments from Kau Bay and the Sulu Sea in Indonesia to examine changes within the WPWP over century and glacial-interglacial time scales, respectively.;Organic matter proxies (delta15N, delta13C, C/N, relative composition and delta13C of fatty acids and alkanes) were analyzed at century-scale resolution from a core from Kau Bay, Halmahera, that spanned over the last ∼3,500 years. These proxies were used to decipher the flushing history of the basin and its relation to El Nino events and warm pool dynamics. Pteropod shells (Creseis acicula) were analyzed from the same cores from Kau Bay for delta 18O, delta13C, and Sr/Ca in order to test the utility of pteropod shells in paleoclimate studies and to determine possible changes in the hydrological cycle within Kau Bay and its relation to equatorial Pacific climate. The C. acicula data showed that Kau Bay water and, therefore, WPWP surface water, was likely warmer 3,000yrBP than throughout the last 2,200 years. Comparisons of this data to other records from the equatorial Pacific and South China Sea revealed that zonal dynamics and the EAM may have had an effect on WPWP and global climate throughout the late Holocene and that ENSO may affect climate change at this resolution.;In the Sulu Sea, the delta18O of thermocline dwelling foraminifera, Pulleniatina obliquiloculata and Neogloboquadrina dutertrei, was analyzed and compared to mixed layer foraminifera to determine that the mixed layer was probably more shallow during interglacial stages than during glacial stages over the last 800kyr, likely in response to changes in sea level and monsoon intensity.