Meltwater Pulse1A Triggered an Extreme Cooling Event: Evidence From Southern China

Abstract

Meltwater Pulse 1A injection into the North Atlantic coincided with the Bølling warming event, despite climate model simulations indicating that the Meltwater Pulse 1A should have inevitably lead to an extreme cooling in the northern hemisphere. However, so far no cooling event has been found in paleoclimate records responding to Meltwater Pulse 1A. Here we reconstruct winter temperature based on sedimentary diatoms from Huguangyan Maar Lake in tropical China. The results show that winter temperature dropped by at least 6°C within ∼100 years at 14.8 ± 0.02 ka BP, coeval with the onset of Meltwater Pulse 1A, within dating uncertainty. We argue that Meltwater Pulse 1A weakened the Atlantic Meridional Overturning Circulation (AMOC), resulting in abrupt severe cooling in the Northern Hemisphere that caused a severe winter temperature drop in East Asia by strengthening the winter monsoon. We propose that extreme cooling in winter temperature triggered the Bølling warming by stopping the freshwater release from the ice‐sheet, triggering the AMOC to recover quickly and causing the Bølling event as an overshoot under gradual forcing.