Consistency and discrepancy in the atmospheric response to Arctic sea-ice loss across climate models
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The decline of Arctic sea ice is an integral part of anthropogenic climate change. Sea-ice loss is already having a significant
impact on Arctic communities and ecosystems. Its role as a cause of climate changes outside of the Arctic has also attracted
much scientific interest. Evidence is mounting that Arctic sea-ice loss can affect weather and climate throughout the Northern
Hemisphere. The remote impacts of Arctic sea-ice loss can only be properly represented using models that simulate interactions
among the ocean, sea ice, land and atmosphere. A synthesis of six such experiments with different models shows consistent
hemispheric-wide atmospheric warming, strongest in the mid-to-high-latitude lower troposphere; an intensification of the
wintertime Aleutian Low and, in most cases, the Siberian High; a weakening of the Icelandic Low; and a reduction in strength
and southward shift of the mid-latitude westerly winds in winter. The atmospheric circulation response seems to be sensitive to
the magnitude and geographic pattern of sea-ice loss and, in some cases, to the background climate state. However, it is unclear
whether current-generation climate models respond too weakly to sea-ice change. We advocate for coordinated experiments
that use different models and observational constraints to quantify the climate response to Arctic sea-ice loss.