This paper is a first effort, based on numerical prediction models, to find out when the first day with less than one million km2 of ice in the Arctic, a condition accepted as an ‘ice-free day’ or change from Arctic white to Arctic blue, might occur.

The conclusions are supported by robust data and methods In fact, daily observation of Arctic ice trends from the National Snow and Ice Data Center at the University of Colorado at Boulder indicates this.

There are many previous works that move in the direction of this paper, but this is the first one that manages to point to the first possible day for a blue Arctic Ocean.

There are no major limitations to consider, as the authors already point out the possible uncertainties. Among these uncertainties is that this first ice-free day must occur between 2027 and 2037, a 10-year interval that is reasonable for a highly variable system such as Arctic ice.

Apart from the work of these two authors providing numerical results, the understanding of the ice system in the Arctic makes the paper extremely plausible: the ice system is a positively feedback non-linear system, i.e. every time the ice surface is reduced, less solar radiation is reflected back into space, the free sea surface gets warmer, this heat is maintained throughout the winter, and the following summer there is less reflective surface. The process is accelerated

The consequences are a very weakened polar jet stream, with large meanders that produce intense and repeated flooding, sharp frosts and intense and repeated heat waves in European latitudes.

In the long term, the melting of Greenland's ice will lead to a sea level rise of about 100 metres. But it is possible that before this, freshwater input from these Greenland glaciers will slow down the AMOC (the global current, one branch of which is the Gulf Stream) over the next few decades, something that is still under study.