Sack Lunch Seminar (SLS)

SLS: Stephen Barker - Cardiff University, UK
Date Time Location
February 10th, 2010 12:10pm-1:10pm 54-915
Participation of the Deep Sea in Abrupt Climate Change and Glacial Termination






Evidence for abrupt temperature variations (Dansgaard-Oeschger or D-O oscillations) over Greenland and the North Atlantic during the last glacial and deglacial periods, as compared with more gradual and out-of-phase variations across Antarctica, has provided stimulus for a role of ocean circulation in abrupt climate change. Recent evidence from the South Atlantic has given support to the notion of a bi-polar seesaw involving the surface ocean of both hemispheres within the rapid climatic oscillations of the last deglaciation. Here we move to the sea floor and present evidence for the direct involvement of the deep ocean in D-O variability. We show evidence for a particularly strong amplification of the Atlantic Meridional Overturning Circulation (an overshoot) during the last deglaciation, directly following the weak mode associated with Heinrich Stadial 1 (HS1). We also show that similar overshoots occurred during every long D-O interstadial of Marine Isotope Stage (MIS) 3 and probably during every glacial termination of the Late Pleistocene.