The impact of projected Arctic sea ice loss on the Tropics: the role of ocean dynamics

Abstract:

While the tropics may influence the pace of Arctic sea ice loss, Arctic sea ice loss can in turn affect tropical climate via oceanic and atmospheric teleconnections. Here we isolate the role of dynamical ocean processes in the global response to projected Arctic sea ice loss by comparing simulations with a hierarchy of models: atmosphere-only, atmosphere coupled to a slab ocean, and atmosphere coupled to a full-depth dynamical ocean. In the absence of ocean coupling, the atmospheric response to Arctic sea ice loss is confined to the northern middle and high latitudes. Thermodynamic ocean coupling expands the reach of the response into the tropics, inducing a northward shift of the Inter-tropical Convergence Zone (ITCZ). Including the effects of dynamical ocean coupling results in an equatorward intensification of the Pacific ITCZ, unlike the thermodynamically-coupled response but similar to the greenhouse gas forced response. The results suggest an important role for ocean dynamics in the response of the full climate system to Arctic sea ice loss.