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Observations(1-3) and model simulations(3,4) show enhanced warming in the Arctic under increasing greenhouse gases, a phenomenon known as the Arctic amplification (AA)(5), that is likely caused by sea-ice loss(1,3). AA reduces meridional temperature gradients linked to circulation, thus mid-latitude weather and climate changes have been attributed to AA, often on the basis of regression analysis and atmospheric simulations(6-19). However, other modelling studies(20-22) show only a weak link. This inconsistency may result from deficiencies in separating the effects of AA from those of natural variability or background warming. Here, using coupled model simulations with and without AA, we show that cold-season precipitation, snowfall and circulation changes over northern mid-latitudes come mostly from background warming. AA and sea-ice loss increase precipitation and snowfall above similar to 60 degrees N and reduce meridional temperature gradients above similar to 45 degrees N in the lower-mid troposphere. However, minimal impact on the mean climate is seen below similar to 60 degrees N, with weak reduction in zonal wind over 50 degrees-70 degrees N and 150-700 hPa, mainly over the North Atlantic and northern central Asia. These results suggest that the climatic impacts of AA are probably small outside the high latitudes, thus caution is needed in attributing mid-latitude changes to AA and sea-ice loss on the basis of statistical analyses that cannot distinguish the impact of AA from other correlated changes.

Warming in the Arctic has been thought to cause mid-latitude weather and climate changes. Simulations show Arctic changes have small influence outside of high latitudes, with background global warming exerting more influence over mid-latitude winter precipitation and wind changes.