Compiled Southern Ocean sea surface temperatures correlate with Antarctic Isotope Maxima

The magnitude and spatial variability of millennial-scale changes in Southern Ocean temperature during Marine Isotope Stage 3 (MIS-3) are poorly constrained. Here we present a compilation of 14 previously published high-resolution sea surface temperature records from 30°S to 70°S. At each site we re-calibrate radiocarbon dates and synchronise records with the Antarctic Ice Core Chronology 2012 and then determine the presence, amplitude and duration of millennial-scale warming that correspond to Antarctic Isotope Maximum (AIM) events. Individual sediment cores recorded warming during an average of 7 out of 10 AIM events. These warming events were then used as tie-points to refine the age models at each site before combining records into Southern Ocean and basin-wide averaged temperature anomaly records or “stacks”. The resulting stacks of Southern Ocean, Atlantic and Indo-Pacific Ocean basin temperature anomalies show a signal consistent with AIM events during MIS-3. Stacked amplitudes of warming are also positively correlated with the amplitude of temperature increases in the EPICA Dome C ice core (n = 10, r² = 0.65, p = 0.001). Additionally, rates of warming in the Southern Ocean are consistent across all warming events. These findings are consistent with the thermal seesaw hypothesis, where a reduction in Atlantic Meridional Overturning Circulation causes decreased cross-equatorial heat transport in the Atlantic resulting in heat accumulation in the south. Our results solidify the link between northern high latitude climate variability, Antarctic temperature and Southern Ocean surface temperature variability during MIS-3. This compilation of records with updated age models tied to the same ice core provides the first basin-scale synthesis of the sea surface temperature changes in the Southern Ocean during the rapid climate changes of MIS-3.