Western Pacific marginal seas in glacial cycles and their global impact

Group GSI.IR
Location International Geological Congress,oslo 2008
Author Wang, Pinxian
Holding Date 08 September 2008

Over 75% of the marginal basins in the modern ocean are concentrated along the Western Pacific continental margin. The Pacific Ocean is separated from the Asian continent by a series of marginal sea, and its western boundary currents, Kuroshio and Oyashio, flow through the marginal seas passing numerous gateways. The Western Pacific marginal seas (WPMS) and the western boundary currents comprise a vulnerable system of sea-land interactions, sensitive to tectonic and eustatic sea level changes.
During the glacial time, emergence of vast shelf areas in the marginal seas, from Sundaland in south to Beringia in north, led to profound changes in heat and vapor transport in atmosphere and in water exchanges of the Pacific with the Arctic and Indian Ocean. Because the gateways between the marginal seas were mostly closed during periods of glacial sea-level low-stand, the western boundary currents drastically reduced their influent into the marginal sea, leading to remarkable climate changes in East Asia. As the California Current, was also attenuated during the glaciation, the changes of both the western and eastern boundary currents might be indicative of glacial shrinkage of the Pacific Subtropical Gyre.
Another major consequence of the glacial geographical and hydrological changes in the WPMS is production of the North Pacific intermediate water (NPIW). In the modern ocean, the NPIW is produced in the Okhotsk Sea and the NW Pacific in result of the Kuroshio-Oyashio mixing. During the glacial time, the NPIW was formed mainly in the Bering Sea, and the enhanced production of the NPIW covered significantly larger area of the ocean and could reach the eastern coast of the Pacific, responsible for the changes recorded in the Santa Barbara Basin.
The paper will discuss the changing teleconnection between the western and eastern boundary currents in the Pacific ocean in glacial cycles, and how the glacial mode of the western boundary currents exerted impact on the exchanges between the high- and low-latitudes. To emphasize the global impact of the WPMS, the sea-land interactions between Asia and the Pacific without marginal seas will also be discussed and illustrated by the Eocene.