October 2019 saw the extent of Arctic sea ice — the surface of the ocean that is covered by ice — reach at its lowest on record.
According to climate scientist Zack Labe, Arctic sea ice extent was more than 2.6 million square kilometres lower than the average between 1981 and 2010 and the lowest on record for a month of October.
Sea ice extent typically falls during the first half of September before growing again in the second half of the month. September extent increased by over 130,000 square kilometres on average during the 1981-2010 period, but this year it actually decreased by 80,000 square kilometres, according to the US National Snow and Ice Data Centre (NSDIC).
That's because of unfavourable weather conditions and because water and surface temperatures in the Arctic Ocean have been higher than usual since late summer. Even with the lack of light, ice has not yet begun to form in northern Alaska and the Chukchi Sea, although it has started to recover in the Siberian area.
"These conditions are consistent with the rapid change of the Arctic," Labe told Euronews in an email.
"The surface temperature was also well above average throughout the Arctic Ocean during the month of October," he added.
For the experts, it is a new test of the "Arctic amplification", the fact that the effects of climate change are twice as large in the Arctic Circle as in the rest of the planet.
"Large areas of open water that would normally be sea-ice covered further contribute to ongoing Arctic Amplification and other positive feedbacks," Labe also said.
Climatologist Xavier Fettewis, from the University of Liège, concurred, flagging to Euronews that abnormally high temperatures are delaying sea ice formation in Greenland.
"The Greenland ice cap is also below average, not because of the thaw but because of snowfalls below average on the west coast and during the summer," he said.
Another factor is that the North Atlantic Multidecadal Oscillation — based on the surface sea-level pressure difference between the Subtropical (Azores) High and the Subpolar Low — has been negative since mid-September, causing "anticyclonic, dry and warm conditions over Greenland and the Arctic," Fettewis explained.
An NSDIC chart clearly shows that the Arctic ice extent has been at record lows between March and July and now, in October, below the historical thaw of 2012.
Scientists recognise that the consequences of these changes in the global climate system are not known with certainty, but point out that the Arctic has an impact on atmospheric currents.
The last report of the UN panel of experts on climate change warned of the silent agony that the icy territories and oceans of the planet are suffering, after a season especially critical for the Arctic.
This year has been marked by several historical records of temperatures, with, for instance, the warmest month ever recorded observed in July.