Abstract/Summary

Previous single model experiments have found that Arctic sea–ice loss can influence the atmospheric circulation. To evaluate this process in a multi–model ensemble, a novel methodology is here presented and applied to infer the influence of Arctic sea–ice loss in the CMIP5 future projections. Sea–ice influence is estimated by comparing the circulation response in the RCP8.5 scenario against the circulation response to sea surface warming and CO2 increase inferred from the AMIPFuture and AMIP4xCO2 experiments, where sea ice is unperturbed. Multi–model evidence of the impact of sea–ice loss on mid–latitude atmospheric circulation is identified in late winter (January–March), when the sea–ice related surface heat flux perturbation is largest. Sea–ice loss acts to suppress the projected poleward shift of the North Atlantic jet, to increase surface pressure in Northern Siberia and to lower it in North America. These features are consistent with previous single–model studies and the present results indicate they are robust to model formulation.