Australia: The Land Where Time Began

A biography of the Australian continent 

Antarctic Surface Waters - Abrupt Cooling and Sea Ice Expansion in the Southern Ocean, South Atlantic Sector at 5,000 Cal Yr BP

Between 10,000 and 5,000 cal yr BP the surface waters around Antarctica were warm and free of ice, based on ice-rafted debris and microfossils present in a piston core taken at 53^o S in the South Atlantic Ocean. According to the authors¹ evidence indicates that about 5,000 cal yr BP sea surface temperatures cooled, sea ice advanced and there was an abrupt increase in the delivery of ice-rafted detritus (IRD) to the subantarctic South Atlantic. These changes marked the end of the Hypsithermal and the onset of Neoglacial conditions. They coincided with an early Neoglacial advance of South American and New Zealand mountain glaciers that occurred between 5,400 and 4,900 cal yr PB, Middle Holocene rapid changes of climate inferred from the Taylor Dome Ice Core in Antarctica, cooling and IRD increase in the North Atlantic, and the closing of the African humid period. It is suggested by these near-synchronous and the abruptness of these climate change events that a link may exist among the tropics and both poles involving a nonlinear response to Northern Hemisphere insolation changes that occurred gradually. In the Middle Holocene the expansion of sea ice in the Southern Ocean may have been a positive feedback that brought hastened the close of the Hypsithermal and African humid periods.

Sources & Further reading

1. Hodell, David A., Sharon L. Kanfoush, Aldo Shemesh, Xavier Crosta, Christopher D. Charles, and Thomas P. Guilderson. "Abrupt Cooling of Antarctic Surface Waters and Sea Ice Expansion in the South Atlantic Sector of the Southern Ocean at 5000 Cal Yr B.P." Quaternary Research 56, no. 2 (9// 2001): 191-98.