24th Pacific Science Congress (PSC-24)

This study investigates the inter-hemispheric climate response to Arctic sea ice loss using a set of model simulations spanning 750 years. We analyze the evolution of the Atlantic Meridional Overturning Circulation (AMOC) and Antarctic sea ice, revealing a complex and temporally shifting teleconnection.
Our simulations indicate that initial Arctic sea ice loss triggers a robust, multi-stage response. Within the first 50 years, a freshening of the North Atlantic leads to a weakened AMOC. Consistent with energy conservation, a reduction in northward ocean heat transport results in increased southward heat transport. This manifests as a rapid increase in Southern Ocean heat content, driving a significant decline in Antarctic sea ice extent and thickness, which reaches a minimum within 30-40 years across all experiments.
Following this initial perturbation, the system evolves through distinct adjustment phases. After ~50 years, the AMOC and Antarctic sea ice begin a transient recovery as the ocean circulation adjusts. Antarctic sea ice rebounds, with the control and moderate-forcing experiments peaking around year 150. In contrast, the high-forcing experiment shows an earlier and weaker recovery, with sea ice peaking by 70-80 years before declining again. This secondary decline in Antarctic sea ice, occurring after the AMOC has stabilized, is strongly correlated with the sustained atmospheric warming and increasing surface temperatures in the Southern Hemisphere.
We conclude that the Arctic's influence on Antarctica is biphasic. The initial decades are dominated by a rapid oceanographic teleconnection, mediated by changes in meridional heat transport and Southern Ocean warming. However, on centennial timescales, the persistent atmospheric warming from the Arctic overshadows the stabilized ocean circulation, ultimately controlling the long-term fate of Antarctic sea ice. Our results highlight the critical role of cross-hemispheric energy redistribution in mediating the polar response to regional climate forcings.
 

Arctic sea ice loss,Antarctic sea ice,Interhemispheric Teleconnections