The Arctic Sea Ice extent is currently the lowest on record for any January 2nd since the satellite series started forty years ago. To be fair this season has been playing nip and tuck with last season (fig 2), but at the moment the 12.542 million square kilometers, which is 90.6% of the average for this day, is slightly lower than the 12.614 at the same time last year (fig 1). This news caught me out a little, because the last time I looked sea ice extent in the Arctic was holding up quite well. The reason behind this is probably down to the fact that the Arctic has been even milder than usual and had a bad Christmas, a bit like the sales figures at Debenhams.
It might be thinner than ever, but Arctic sea ice this Autumn is doing much better than it did last year, with the sea ice extents up by around 800,000 square kilometres at 88.2% of the 1981-2010 long-term average, compared with being only 81.0% of average in November 2016 (fig 1).
In the Antarctic things are also not quite as dire as they were last Autumn, and although this Autumns sea ice extent is tracking well below the x 2 standard deviation area (light grey) at 91.6% of the 1981-2010 long-term average, it’s almost a million square kilometres higher than at the same time last year (fig 2).
There’s the usual ring of abnormally high positive temperature anomalies around the Arctic at the start of November (fig 1). I had a theory that the largest anomalies were located in areas of open water where no sea ice had formed, but this theory doesn’t look too plausible judging by the latest sea ice extent chart (fig 2). I notice that the recent cold weather in Canada has encouraged early ice formation around the coast of the Hudson Bay, but the area to the north of the Chukchi sea look severely depleted of any sea ice again for this time of the year.
The National Geographic magazine have just noticed a large increase in the Weddell Sea polynya (south of south America) that I brought to your attention earlier last month in an article that I found on the phys.org website. I can confidently predict that the polynya will continue to increase in size till it totally disappears later in the Antarctic summer!
It looks like this Winters maximum sea ice extent has been reached in the Antarctic a little earlier than average. The spot value for the 12th of September was 18.023 million square kilometres was the lowest maximum in the satellite record that started in 1979, but it was a very near thing, because the 2017 figure was just 4,000 square kilometres lower than the previous lowest maximum of September 1986. The sea ice could surge again and prove me a liar, but I got it right with the Arctic minimum, so maybe I’m on some kind of roll (pardon the pun).
Here is the table sorted from lowest to highest on maximum extent (fig 2). Before you ask 1978 is top of the list because the satellite record started on the 26th of October 1978, and the maximum for that year will have occurred a month earlier and been considerably higher than that figure, blame it on the programmer.
I would say on balance that the Antarctic sea ice extent has bounced back extremely well after what was a pretty dreadful start, back on the 1st of March sea ice extent was just 69.8% of the long-term average for that date, on the 12th of September they were back up at 97.4% of the long-term average for that day. This is the latest rather interesting ice extent picture for the Antarctic from the NSIDC (fig 3), which shows another polynya in the Weddell sea similar to the one in the news item I posted earlier this month. Who knows, maybe if that polynya hadn’t opened up, 2017 might not have been the new record low year!
I might be jumping the gun here but…
I think the Arctic sea ice minimum as measured by the NSIDC, reached its summer minimum on September 12th at 4.611 million square kilometres, making 2017 the 8th lowest minimum in the satellite series that started in 1978. The value was over 500,000 square kilometres higher than last years minimum. I’ll bring you the latest news from the Antarctic about the maximum, because the season down there has still not quite finished.
I noticed this interesting article about polynya on the Phys.org website (you might what to add this to your favourites because it looks a great site) that might interest some of you out there. I was thinking, it’s only because the upwelling of warm water occurs under an ice sheet that we realise that they’re happening at all. They must happen all the time in the worlds oceans, but we just don’t see them, apart I suppose from anomaly charts of very sensitive SST satellite sensor data.