How long will the Arctic ice pause last?

Twenty years ago, it would have taken a bold scientist to go against the consensus and predict that a sustained pause in Arctic ice-loss was imminent. Even ten years ago, there were predictions of ice-free summers within a decade or so. Yet, it happened. Although Arctic ice extent has halved since the first satellite records began in 1979, over the past two decades Arctic sea-ice loss has slowed considerably, with no statistically significant decline in September extent – the annual minimum. But you can sometimes make even such unequivocal (albeit noisy) data say something else. Specifically, deny a the ice-pause is significant because it might, or might not continue!

Many scientists skirt over the inconvenience of the recent pause in the loss of Artic sea ice by referring to a long-term decline. But the pause is definitely real – it is robust across several observational datasets, metrics, and seasons. It even crops up in climate models, such as CMIP5 and CMIP6. These suggest that such periods with no sea-ice decline under increasing greenhouse gas emissions are not unusual.

Some models suggest that the current pause could persist for another five to ten years, possibly longer, although this is a conclusion reached in the face of considerable uncertainty. This leads to the question of which feature of Arctic ice variability is the most significant: the decline seen after 1979 or the hiatus of the past 20 years?

The uncertainty is illustrated by scientists from the University of Exeter and Columbia University, New York writing in a paper submitted to Geophysical Research Letters, who state that they are not even certain of what human influences could have been on the ice-pause.

If anything this teaches us that we should be humble about multi-decadal predictions of any climate parameter. Looking back on the Arctic sea-ice extent predictions, we see they have been overly alarmist, in keeping with many other climate projection proclamations.