Timings and causes of glacial advances across the PEP-II transect (East-Asia to Antarctica) during the last glaciation cycle

Abstract

A comparison of glacial advances through the last glacial cycle between Northern and Southern Hemispheres in the PEP 2 transect (East Asia and Australasia) revealed (1) a relatively good synchrony of glacial advances during the LGM across the whole transect except Antarctica, (2) a rough synchrony in glacial advances in the Karakorums, Himalayas, Japan, and New Zealand during Marine Isotope Stages (MIS) 3 and 4, although the age control is still poor, and (3) a greater glacial extent in MIS 3 and 4 than in MIS 2. The LGM advances are driven by Northern Hemisphere temperature forcing, but the MIS 3 and/or MIS 4 advances appear to be dominantly controlled by the effects of moisture availability or lack of thereof. In mainland Australia and Antarctica glaciers advanced only in the most humid phases. In Himalaya and Karakorum, where the moisture is supplied both by a summer monsoon and the westerlies, timings of glacier advance coincide with both summer monsoon enhancement and westerly intensification. In Japan the glacier extent is controlled by monsoon changes, sea-surface temperatures (SSTs) in the Japan Sea (moisture source) and by zonal shifts in westerly circulation. In New Zealand, either insolation changes or changes in the intensity of westerly circulation are invoked, as the main track of the westerlies did not change greatly during glacial times.