Ocean heat transport nearly halves Arctic amplification and sea-ice loss over the 21st century

Abstract:

The enhanced warming of the Arctic, relative to other parts of the Earth, a phenomenon known as Arctic amplification, is one of the most striking features of climate change. Arctic amplification has important climatic impacts affecting the entire Northern Hemisphere, and it is thus critical to understand its causes. Several mechanisms are believed to be responsible for Arctic amplification; however, a quantitative understanding of their relative importance is still missing. In particular, the contribution of ocean heat transport remains uncertain, in both sign and magnitude. Here, using ensembles of model integrations, we quantify its contribution to Arctic amplification over the 20th and 21st centuries, and show that ocean heat transport reduces the Arctic warming and sea-ice loss by ~40% , thus delaying ice-free conditions by ~15 years, on average. Our results demonstrate the utility of targeted numerical experiments to quantify the role of specific mechanisms in Arctic amplification, for better constraining climate projections.