Antarctic, Southern Ocean, and Global Ocean Temperatures During Dansgaard–Oeschger Events

Abstract

Global Mean Ocean Temperature (GMOT) changes are thought to be both an important consequence and a possible cause of Dansgaard–Oeschger (DO) events, a series of abrupt climate changes during the last glacial. Despite extensive reconstructions of GMOT from ice cores for other periods, no reliable reconstructions exist for Marine Isotope Stage 3, when DO events were most common. We investigate model simulations showing unforced DO‐like oscillations alongside existing proxy reconstructions of Southern Ocean and Antarctic temperatures, which we show to be strongly linked to GMOT in the models though with consistently larger changes in Antarctic temperature than GMOT. We find that the models reproduce DO events following non‐Heinrich stadials well, but that the GMOT changes they show across these events are comparable to the measurement error for ice core GMOT reconstructions and so would be difficult to detect. The simulations we use, which are not forced by Heinrich meltwater, do not capture the larger Southern Ocean and Antarctic warming associated with DO events that follow Heinrich stadials, making extrapolating our results to these events challenging. Additionally, there is a statistically robust disagreement between the proxies and models regarding the relative warming in Antarctica and the Southern Ocean, which adds further uncertainty to our estimates of GMOT warming. Nonetheless, we find that the GMOT changes across these larger DO events in MIS3 would be detectable. Given the importance of GMOT for understanding DO events, these should therefore be priority targets for future efforts to reconstruct GMOT from ice cores.