The Arctic sea ice minimum was declared to have been reached on 16 September this year (4.72 mkm2), breaking no records.
Ice extent can only go up from this point forward but at this time of year, it happens slowly and isn’t noticeable in the Arctic Basin as much as it is in the Canadian Arctic Archipelago. As I wrote about last year, new ice development in the fall next to shore creates upwelling conditions that attract fish and seals, and therefore provides feeding opportunities for polar bears.
The same process likely happens when new ice forms next to old ice. These few weeks of developing sea ice, wherever they occur, are the last chance polar bears have to replace weight lost over the summer before the cold and darkness of winter reduces hunting opportunities to virtually nil.
Sea ice in Canada
The beginnings of new ice growth in the Western Canadian Arctic shows as light and dark purple on this ‘stage of development’ chart (below) from the Canadian Ice Service for the week of 27 September 2021:
Below is the same chart for Eastern Canada:
Expansion of Arctic Basin pack ice
We need detailed daily ice charts to see the pack ice expanding at this time of year and one of the places this is possible is in the Barents Sea, courtesy the Norwegian Ice Service:
In particular, the ice around the Svalbard Archipelago north of Norway has been increasing over the last couple days as shown in this NIS Sea Ice Index graph:
This is what the ice extent looked like on the 24 September chart, around its low point:
But on the 29th, you can see Arctic Basin pack ice re-advancing towards the islands from the north and a bit of coastal ice forming:
These conditions will change rapidly over the next few months, of course, but it’s interesting to see this essential Arctic transition in the early stages. Polar bears depend on it.