Future trends in the vertical structure of Arctic warming and moistening in different emission scenarios

Arctic warming is a pressing global concern, and understanding its future vertical structure is crucial for Arctic-mid-latitude connections. In this study, we employed the Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model simulations to investigate the vertical structure of Arctic warming concerning its current evolving (1980–2030) and future change (2050–2100). In addition to the dry atmosphere described only by temperature, this study analyzed humidity and moist static energy (MSE) for the moist (with the effect of moisture explicitly presented) atmosphere. Under the high-emission scenario, Arctic warming is projected to accelerate, while maintaining its existing bottom-heavy structure. Amplified humidity increases are anticipated in both the tropics and the Arctic, with the Arctic exhibiting greater moisture increases in percentage. Furthermore, we find that MSE, serving as a comprehensive metric for moist atmospheric warming, is projected to accelerate in the Arctic under the high-emission scenario. As a result, the warming of both the dry and moist atmospheres will intensify in the future, with the bottom-heavy vertical structure persisting due to enhanced warming and moistening in the lower troposphere. The accelerated Arctic moistening in the future is due to meridional atmospheric moisture transport in the summer and local moisture source in the winter. In contrast, under the intermediate-emission scenario, Arctic warming and moistening are not projected to accelerate. Despite the inter-model discrepancy, our findings underscore the reliability of projections derived from the high-emission scenario. In summary, our findings highlight that the bottom-heavy vertical structure of Arctic warming will not change and that enhanced upper-level Arctic warming will not occur in the future.