Emergence of a climate oscillation in the Arctic Ocean due to global warming

Global warming is expected to be able to trigger abrupt transitions in various components of the climate system. Most studies focus on abrupt changes in the mean state of the system, while transitions in climate variability are less well understood. Here, we use multimodel simulations to show that sea-ice loss in the Arctic can trigger a critical transition in internal variability that leads to the emergence of a new climate oscillation in the Arctic Ocean. The intensified air–sea interaction due to sea-ice melt causes an oscillatory behaviour of surface temperatures on a multidecadal timescale. Our results suggest that a new mode of internal variability will emerge in the Arctic Ocean when sea ice declines below a critical threshold. Abrupt transitions in the climate system are discussed mostly in terms of mean state changes. Here, the authors use simulations to show that a decline in Arctic sea ice can lead to a new multidecadal mode of surface temperatures in the Arctic Ocean.