Atmospheric and Oceanic Pathways Drive Separate Modes of Southern Hemisphere Climate in Simulations of Spontaneous Dansgaard-Oeschger-Type Oscillations

Dansgaard-Oeschger (DO) events are a dominant mode of millennial-scale climate variability during the last glacial period with most pronounced impacts in the North Atlantic region. In Antarctica, they manifest primarily as a muted and phase-shifted temperature signal, but recent studies suggest an additional in-phase component. Here, we analyze the Southern Hemisphere (SH) response to spontaneous DO-type oscillations in a general circulation model. The dominant Antarctic temperature mode is phase-shifted compared to Greenland temperature variations and consistent with the oceanic pathway described by the bipolar seesaw model. However, the leading SH atmospheric circulation mode varies synchronously with Greenland temperatures. A westward-shifted Walker circulation and strengthened Hadley cell during Greenland temperature maxima cause zonally heterogeneous jet stream anomalies differing from the Southern Annular Mode pattern. Comparison of simulated ${\delta }^{18}$O with speleothems and ice cores indicates a good agreement in the tropics and SH mid-latitudes but deviations in Antarctica warrant further research.