Persistent teleconnection of North Atlantic and sub-Antarctic climate anomalies during the last glacial period

Abstract:

The ability of the climate system to shift abruptly is exemplified by the so-called Dansgaard-Oeschger (D-O) cycles recorded in the Greenland ice cores, which involved temperature changes of several degrees within decades. It has been suggested that these abrupt climate fluctuations were accompanied by variations of the Atlantic Meridional Overturning Circulation (AMOC) and associated sea ice feedback mechanisms. However, a paucity of well-dated and well-resolved marine climate archives, in particular from the southern hemisphere, has hampered our understanding of the exact role of the AMOC in these abrupt climate perturbations. Indeed, it remains unclear whether significant AMOC changes contributed to all DO-cycles. We present sub-millennially resolved proxy evidence for abrupt shifts in the deep ocean circulation and the presence of sea ice in the sub-Antarctic Atlantic during the last glacial period, both of which show a remarkable resemblance to abrupt climate variability over Greenland. Our results demonstrate persistent perturbations of the AMOC geometry, if not its overturning rate, across the entire Atlantic Ocean in association with each D-O cycle of the last glacial period. The quasi-instantaneous transmission of North Atlantic climate anomalies to both the surface- and the deep Southern Ocean implicates a very efficient oceanic and/or atmospheric teleconnection, which will be further discussed.