Lessened projections of Arctic warming and wetting after correcting for model errors in global warming and sea ice cover.

Credible projections of Arctic warming and wetting (AWW) are essential for informed decision-making in a changing climate. However, current AWW projections from state-of-the-art climate models carry uncertainties. Using observational datasets and CMIP6 model simulations, we demonstrate that the observed historical global warming trend and the climatological mean pattern of Arctic sea ice can serve as effective constraints on AWW projections. Under SSP2-4.5, the constrained warming by the end of the century is reduced from 5.5° to 4.6°C. Similarly, the projected wetting decreases from 6.8 to 5.7 millimeter per month. The inter-model spread in warming and wetting is reduced by 25 and 15%, respectively. The reduction is the largest in the Barents-Kara seas, reducing warming by 1.2°C, lessening wetting by 1.7 millimeter per month, and decreasing the inter-model spread by one-third. Our findings suggest that unconstrained CMIP6 projections overestimate future AWW, particularly in the Barents-Kara seas, due to an overestimation of historical global warming and excessive sea ice in the models.