Influence of Northward Heat Transport on Arctic Amplification in the Community Earth System Model Version 1 Large Ensemble

The Community Earth System Model Version 1 Large Ensemble simulation for 1950-2100 is used to investigate the role of poleward heat transports from midlatitude into the Arctic by the ocean and atmosphere in Arctic warming and sea-ice melting. Our results show a large increase toward the end of the 21^st century in ocean heat transport (OHT) into the Arctic. Furthermore, the ensemble spread is used to show that the ocean heat transport increase is significantly correlated with both Arctic amplification and sea-ice reduction. The ocean heat transport through the Barents Sea Opening exhibits the largest trend, which is followed by those through the Bering and Fram Straits. While the AMOC transport is projected to decrease in all 40 members, the ocean volume transport into the Arctic is projected to be stable in 1950-2100. Thus the increasing OHT can be attributed primarily to the warming in the subarctic North Atlantic. Although the changes in atmospheric heat transport (AHT) are on the same order as the changes in ocean heat transport, the net AHT exhibits a decreasing trend, thus the two are overall compensated. The total decreasing trend in AHT results from a difference between increasing latent energy transport and a larger decrease in dry static energy transport. However, unlike the OHT, the ensemble spread in AHT changes does not exhibit any significant correlation with the Arctic amplification or sea-ice change.