Near-term and Large-scale Coupled Climate System Responses to Arctic Sea-ice Loss

Amelie Simon, LOCEAN-IPSL, Paris, France, Guillaume Gastineau, LOCEAN-IPSL, Paris cedex 05, France, Claude Frankignoul, Sorbonnes Universit├ęs LOCEAN, Paris, France and Francis Codron, Univ Pierre and Marie Curie-Paris 6, LOCEAN, Paris, France
Rapid changes in the Arctic have been observed and are expected to be amplified in future. However, the influence of Arctic sea-ice decline on global climate remains under debate. We focus on a modeling analysis of the ocean-atmosphere responses to a near-term Arctic sea-ice loss (corresponding to the period 2035-2055 under the RCP8.5 scenario). With the coupled model IPSL-CM5A2, two different methods to melt Arctic sea-ice are implemented to estimate the robustness of the protocol. We will show that modifying the albedo or changing the thermal conductivity of the Arctic sea-ice show similar pattern responses but with different magnitude. It is also found that, at the 10% significance level, Arctic sea-ice decline leads to large-scale circulation responses such as a negative North Atlantic Oscillation (NAO) associated with southward shift of the westerlies; an expansion north of the North Atlantic current; a weaker Atlantic Meridional Overturning Circulation (AMOC) linked to a shallower mix layer depth at subpolar North Atlantic deep-convection site; a southward shift of the Intertropical Convergence Zone (ITCZ); a tropical Pacific cooling and a positive Southern Annular Mode (SAM).