Arctic cyclone activity changes under a warming climate

Arctic cyclones play a crucial role in regional climate and have important linkages to mid-latitude processes. However, their future changes and driving mechanisms remain uncertain. By applying Lagrangian tracking to CMIP6 models under the SSP5-8.5 scenario, this study projects future Arctic cyclone activity changes and quantitatively investigates the relative contributions of local cyclogenesis and externally migrating systems. By the late 21st century, Arctic cyclone activity is projected to decline, with distinct seasonal and regional differences. Winter reductions stem from weakened local cyclogenesis, especially in the subpolar North Atlantic, while increased external migration intensifies cyclone activity in the Bering Sea and northeast Siberia. Summer declines result largely from reduced poleward intrusion of mid-latitude cyclones, particularly along continental margins. Yet increased cyclones around Greenland are driven by enhanced local cyclogenesis. These changes in local cyclogenesis and external migration are closely tied to variations in baroclinic instability and large-scale atmospheric flow patterns, respectively.