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.

预计全球变暖将能够触发气候系统各个组成部分的突然转变。大多数研究集中在系统平均状态的突然变化上，而气候变率的变化则不太了解。在这里，我们使用多模式模拟来表明，北极的海冰损失可以触发内部变率的关键转变，从而导致北冰洋出现新的气候振荡。由于海冰融化而加剧的气海相互作用导致地表温度在多年代际时间尺度上出现振荡行为。我们的结果表明，当海冰下降到临界阈值以下时，北冰洋将出现一种新的内部变率模式。