Arctic amplification, and its seasonal migration, over a wide range of abrupt CO2 forcing
Yu‐Chiao Liang, Lorenzo M. Polvani, Ivan Mitevski
Abstract
Abstract Arctic amplification (AA), the larger warming of the Arctic compared to the rest of the planet, is widely attributed to the increasing concentrations of atmospheric CO 2 , and is caused by local and non-local mechanisms. In this study, we examine AA, and its seasonal cycle, in a sequence of abrupt CO 2 forcing experiments, spanning from 1 to 8 times pre-industrial CO 2 levels, using a state-of-the-art global climate model. We find that increasing CO 2 concentrations give rise to stronger Arctic warming but weaker AA, owing to relatively weaker warming of the Arctic in comparison with the rest of the globe due to weaker sea-ice loss and atmosphere-ocean heat fluxes at higher CO 2 levels. We further find that the seasonal peak in AA shifts gradually from November to January as CO 2 increases. Finally, we show that this seasonal shift in AA emerges in the 21st century in high-CO 2 emission scenario simulations. During the early-to-middle 21st century AA peaks in November–December but the peak shifts to December-January at the end of the century. Our findings highlight the role of CO 2 forcing in affecting the seasonal evolution of amplified Arctic warming, which carries important ecological and socio-economic implications.