Surface changes in the Eastern Labrador Sea around the onset of the Little Ice Age

摘要

Despite the relative climate stability of the present interglacial, it has been punctuated by several centennial time scale climatic oscillations, the latest of which are often colloquially referred to as the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA). The most favored explanation for the cause of these anomalies is that they were triggered by variability in solar irradiance and/or volcanic activity and amplified by ocean-atmosphere-sea ice feedbacks. As such, changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) are widely believed to have been involved in the amplification of such climatic oscillations. The Labrador Sea is a key area of deep water formation. The waters produced here contribute approximately one-third of the volume transport of the deep limb of the AMOC and drive changes in the North Atlantic surface hydrography and subpolar gyre circulation. In this study, we present multi-proxy reconstructions from a high-resolution marine sediment core located south of Greenland that suggest an increase in the influence of polar waters reaching the Labrador Sea close to MCA-LIA transition. Changes in freshwater forcing may have reduced the formation of Labrador Sea Water and contributed towards the onset of the LIA cooling.