Abrupt climate changes caused by meltwater pulses in the Labrador Sea during the last glacial termination

Abstract

<p>The last glacial termination is an unstable transition state characterized by abrupt climate changes, while the related physical mechanisms are still not fully understood. Here, we present well-dated high-resolution sedimentary records from the eastern Labrador Sea representing the last 23 ka. Based on our biomarker records, there was seasonal to permanent sea ice cover before 11.7 ka BP. During 11.7 to 8.2 ka BP, ice-free conditions were interrupted by several sea ice expansions, while no sea ice after 8.2 ka BP. Besides Heinrich Event 1, four prominent cold events have been identified during 14 ka to 8.2 ka BP. These abrupt events are marked by increases in sea ice, decreases in sea surface temperature, and weak deep current intensity. We propose that these events were mainly triggered by collapses of the Laurentide Ice Sheet and/or Greenland Ice Sheet, resulting in icebergs/meltwater in pulses into the Labrador Sea. This caused surface freshening, which potentially promoted the stratification of surface water, prevented the northward inflow of Atlantic Water, and limited deep water production in the Nordic Seas, consequently disrupting the climate.</p>