8.4 The role of the North Atlantic Thermohaline Circulation as a possible trigger for the Younger Dryas Osccliation

Thursday, 12 July 2012: 11:15 AM
Essex North (Westin Copley Place)
Manuscript (1004.8 kB)

The Younger Dryas Oscillation occurred at approximately 12.8 kyr B.P. ( Before Present) and was characterized by an abrupt departure of the mean longitudinal temperature trend during this time. As the amelioration of Wisconsin Ice Epoch was well underway, this anomaly manifested initially as a rapid decrease in surface temperature of 5 c to 10c over a period of mere decades, followed by warming of equal magnitude. A number of hypotheses have been propounded to explain this abrupt climate change event including coupling with shifts in atmospheric composition (greenhouse gases), a bolloid impact and ejection of atmospheric aerosols, to a disruption in the thermohaline circulation (THC) in the North Atlantic Basin. In the case of the latter hypothesis, it has been suggested that the release of fresh water into the Atlantic Basin from the ablation of the Laurentide ice sheet resulted in a break down of the North Atlantic conveyor belt / thermohaline circulation hence heat distribution. The net impact was an accelerated cooling via a positive feedback loop composed of increased snowfall commensurate with decreased surface albedo leading to this interstadial cooling. This paper will investigate the North Atlantic THC and its contributions as a trigger for the Younger Dryas event.

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