Sci. Adv. 4, eaat6025 (2018)

Studies have suggested that Arctic sea-ice loss can be linked to an increased occurrence of cold extremes across Eurasia. However, the robustness of this connection has been debated due to inconsistencies between model analyses. Using perturbation experiments performed with an atmospheric model that comprehensively represents stratospheric processes (SC-WACCM4), Pengfei Zhang from Purdue University, USA, and colleagues further investigate the atmospheric response to Arctic sea-ice loss.

Credit: Pavel Filatov/Alamy Stock Photo

A robust wintertime cooling is found across Eurasia, largely in Siberia, in response to imposed ice loss in the Barents–Kara seas. This cooling pattern is attributed to an enhanced Siberian High, characterized by a ridge anomaly near the Ural Mountains and a trough over East Asia, favouring the southward advection of cold anomalies and cold air outbreaks across Siberia. The downward influence of the stratosphere is integral in producing a coherent warm Arctic–cold Siberia pattern, with simulated temperature anomalies much warmer when the stratospheric pathway is absent. These results highlight a robust Arctic–mid latitude connection, but emphasize that stratospheric processes must be incorporated when diagnosing relationships between the two.