Reversal of the warm Arctic–cold Eurasia intraseasonal coupling by CO 2 removal

Abstract Midlatitude winter climate variability arises partly from its interactions with Arctic climate variability. A prominent example is the intraseasonal coupling between warm temperature anomalies over the Barents–Kara Seas and cold anomalies over central Eurasia, commonly referred to as the warm Arctic–cold Eurasia (WACE) relationship. Numerous studies have examined how this coupling may weaken under continued greenhouse gas warming. Yet, it remains unclear whether the WACE response to CO 2 warming reflects an irreversible change in atmospheric circulation or a reversible response to altered background conditions. In this study, the reversibility of the WACE relationship is investigated using a large-ensemble CO 2 ramp-up and ramp-down experiment. The WACE relationship is projected to weaken under increasing CO 2 concentrations. This weakening is largely reversed when CO 2 concentr…