Australia: The Land Where Time Began

A biography of the Australian continent 

Decoupling of Air-Sea Temperature in Western Europe During the Interglacial-Glacial Transition

A decrease in summer insolation is said by the authors¹ to have controlled a period of continental ice growth, the Marine Isotope Stage (MIS) 5a/4 transition, between about 80,000-70,000 BP, that was among the 4 largest expansions of ice to have occurred in the past 250,000 years (Ruddimann & McIntyre, 1981). It has been proposed that the warm subpolar and northern subtropical Atlantic Ocean are the sources of the moisture for this expansion of ice (Ruddiman & McIntyre, 1981; Ruddiman & McIntyre, 1979). It is unclear what the mechanism was that allowed the continuous growth of the ice sheets through 3 subtropical cooling events, associated with the discharge of icebergs in the North Atlantic (McManus et al., 1994; Chapman & Shackleton, 1999), and cooling over Greenland (Dansgaard et al., 1984; Anderson et al., 2006), that occurred during this period. In this paper the authors¹ reconstruct parallel records of sea surface temperatures from the marine microfossil record and air temperatures from pollen data, from 2 sediment cores collected within the northern subtropical gyre. Throughout the MIS5a/4 transition the thermal gradient between the cold air and the warmer sea increased, being marked by 3 intervals during which there were thermal gradients that were even more pronounced that were associated with the C20, C19 and C18' cold events. The authors¹ argue that along the western European margin the warm ocean surface provided a source of moisture that was transported by northward-tracking storms to feed the ice sheets in colder Greenland, northern Europe and the Arctic.

Sources & Further reading

1. Sanchez Goni, Maria Fernanda, Edouard Bard, Amaelle Landais, Linda Rossignol, and Francesco d/'Errico. "Air-Sea Temperature Decoupling in Western Europe During the Last Interglacial-Glacial Transition." Nature Geosci 6, no. 10 (10//print 2013): 837-41.