Multidecadal ocean variability and NW European ice sheet surges during the last deglaciation

Abstract

A multiproxy paleoceanographic record from the Atlantic margin off the British Isles reveals in unprecedented detail discharges of icebergs and meltwater in response to sea surface temperature increases across the last deglaciation. We observe the earliest signal of deglaciation as a moderate elevation of sea surface temperatures that commenced with a weakly developed thermocline and the presence of highly ventilated intermediate waters in the Rockall Trough. This warming pulse triggered a series of multidecadal ice‐rafted debris peaks that culminated with a major meltwater discharge at 17,500 years before present related to ice sheet disintegration across the NW European region. The impact of meltwater caused a progressive reduction in deep water ventilation and a sea surface cooling phase that preceded the collapse of the Laurentide Ice Sheet during Heinrich event 1 by 500–1000 years. A similar sequence of rapid ocean‐ice sheet interaction across the European continental margin is identified during the Bølling‐Allerød to Younger Dryas transition. The strategic location of our sediment core suggests a sensitive and rapid response of ice sheets in NW Europe to transient increases in thermohaline heat transport.