Australia: The Land Where Time Began

A biography of the Australian continent 

During the Transition from the Last Interglacial to the Last Glacial Air-Sea Decoupling Occurred in Western Europe

An increase in summer insolation that occurred between about 80,000-70,000 years ago controlled a period of continental ice growth that was among the 4 largest expansions of ice over the last 250,000 years (Dansgaard, W. et al., 1998). The subpolar and northern subtropical regions of the Atlantic Ocean have been proposed as the source of the moisture for the expansion that occurred during the Marine Isotope Stage (MIS) 5a/4 transition (Dansgaard, W. et al., 1998; Peterson et al., 2000). The mechanism responsible for keeping the glaciers growing through 3 suborbital cooling events within this period, which were associated with the discharge of icebergs into the North Atlantic (Brook et al., 2000; Broecker, Peteet & Rind, 1985), as well as the cooling over Greenland (Chiang & Bitz, 2005; Wang et al., 2007) has remained uncertain. In this study the authors¹ reconstructed parallel records of sea surface temperatures (SSTs) and air temperatures based on data from marine microfossils and pollen, respectively, obtained from sediment cores that 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 the thermal gradients associated with C20, C19 and C18’ cold events were even more pronounced. The warm surface of the ocean along the margin of western Europe has been argued by the authors¹ to have provided a source of moisture that was transported to feed the ice sheets in colder Greenland, northern Europe and the Arctic by storms that were northward tracking.

Sources & Further reading

1. Sanchez Goni, M. F., et al. (2013). "Air-sea temperature decoupling in western Europe during the last interglacial-glacial transition." Nature Geosci 6(10): 837-841.