Retreat velocity of the North Atlantic polar front during the last deglaciation determined by 14C accelerator mass spectrometry

Abstract

The glacial oscillations which dominate the Quaternary global climate are closely related to changes in incoming solar radiation, but the details of palaeoclimatic spectra suggest that other parameters, usually referred to as feedback, have significantly increased the climatic response to extraterrestrial forcing1. The last deglaciation appears to be one of the more characteristic examples of nonlinearity because its abruptness strongly contrasts with the smooth shape of the associated solar radiation maximum dated at ∼11,000 yr BP. In addition, the presence of the Younger Dryas cold event, concomitant with the solar radiation maximum, could be interpreted as a transitory phenomenon caused by the rapid meltwater influx linked to the first phase of the ice-sheet's disintegration2,3. Here, using accelerator mass spectrometry, we date precisely the movements of the polar front during the whole period of glacial retreat ∼15,000–8,000 yr BP. Our results show that the polar front has moved between 35° N and 55° N in < 1,000 yr for the earliest retreat ∼12,500–12,000 BP and moved almost 'instantaneously' (that is < 400 yr) during the two abrupt climatic changes associated with the Younger Dry as cold event.