Recent Eurasian winter temperature change and its association with Arctic sea-ice loss

The surface air temperature in the northern mid-latitudes during winter showed a significant cooling trend from the late 1990s to the early 2010s, in spite of increasing greenhouse gas concentrations. This unexpected cooling, which was particularly strong across Eurasia, has been partly attributed to Arctic sea-ice loss. Here, the statistical relationship between Arctic sea-ice loss and surface air-temperature change during winter in Eurasia, which is often referred to as the warm Arctic-cold Eurasia pattern, is re-evaluated by using a break-point trend analysis and maximum covariance analysis. A significant time-lagged covariability is observed between the Arctic sea-ice concentration over the Barents-Kara seas and the Eurasian surface air temperature during winter, with the former leading the latter by approximately two months. More importantly, the timing of an abrupt decline in the autumn Arctic sea ice that occurred in the late 1990s is coincident with the beginning of the Eurasian winter cooling. This concurrent trend change is statistically significant and robustly found in both the break-point analysis and maximum covariance analysis. These results suggest that both the inter-annual variability and decadal trend change seen for the surface air temperature during Eurasian winters are likely influenced by regional sea-ice changes over the Barents-Kara seas.