It’s no wonder that the latest Antarctic sea ice extent figure of 76.2% (of the long-term average for the 14th of January) is so low when you look at the mean temperature anomalies for the first two weeks of the year. There are two very large warm anomaly ‘bullseyes’ over the Antarctic, one directly over the continent itself of +20°C, and another more elongated anomaly in the Ross Sea of +16°C. They remind me of the kind of warmth and the anomalies I’ve seen over the Arctic in the last few years, maybe just not quite as large, but very similar and to me very surprising. As far as I know these anomalies (which I calculate against the 1948-2014 long-term average) are correct, please let me know if you think I’ve screwed up!
A very interesting news article from Pallab Ghosh on the BBC News this afternoon for anyone interested in the global climate and sea ice. It appears that Antarctic sea ice extents are very similar to what they were a hundred years ago, according to a report that used log books from the early expeditions to the continent.
I would link directly to the article on the BBC news website, but for some reason although the BBC provide a link to allow sharing with other social media apps, strangely they don’t for WordPress.
Just to emphasise the plight of polar sea ice which is now firmly planted on the endangered species list right below the Siberian Tiger, I thought I would try to emulate some of the fancy charts that have been doing the rounds on the internet that attempt to visualise 38 years of daily sea ice extents in a single line graph. It’s a little bit tricky with my number of active brain cells just to get the right grey scale colours for the line series and the x-axis to plot correctly, but three hours later and et voilà !
I’ve been going on about the dire state of the Arctic sea ice this autumn and this chart shows exactly why. The sea ice extent has never been in these unchartered warmer than average waters before as the red line in the chart shows. Never mind let’s see how the Antarctic is performing, in recent years its being doing so well…
Well what do you know that’s crashing as well and also deep in uncharted waters as the red line above shows. The thinner blues line is where it was as recently as 2014, just what is going on? Finally if you add the total for the Arctic with the total for the Antarctic you get the global polar sea ice extent. I’ve never done much with these statistics before, so I was surprised to find that last year (2015) they hit a minimum, and the way things are going that record minimum is going to be broken again, I would say smashed but that might be sensationalist, probably around February of 2017, because by that time we will have probably set a new low Arctic maximum and a new low Antarctic minimum – the perfect storm for sea ice.
After a very early minimum (7 September) Arctic sea ice started very strongly to get itself back above the 2 x standard deviation [2xSD] region (the very light grey area in the graph) during the remainder of September. That acceleration ran out of steam (pardon the pun) and the sea ice extent has now fallen back well below the 2xSD and is currently the lowest it’s ever been for the 19th of October since theses records started in 1978. It’s a shade lower than it was in 2007 and only 69.9 of the average for this day so less than 30% below normal.
Looking at the Arctic ocean there seems to be a dearth in sea ice along both the Russian Siberian coast in the east and the Alaskan Canadian coast in the west. It looks pretty dire for so early in the season, and must have a knock on effect in the coming the northern hemisphere winter in some way.
I would like to report that in the Antarctic things are looking up but I’m afraid not! The gains in recent years are a thing of the past , and the early maximum this year on the 28th of August is a sign that things aren’t any better down under. The extent has just slipped out of the 2xSD area of the graph and currently for the 19th of October is the lowest it’s ever been on that day of the year. The good news is that it’s less that 5% lower than average, and not 30% lower as in the Arctic. The eagle-eyed amongst you will be wondering why 1986 isn’t top of the lowest table, the reason is that reports back then were every other day and not daily.
It’s hardly surprising in what will more than likely be the warmest year on record globally, so you’ll have to get used to more Winter’s devoid of snow as I have in Devon during recent years, running outside in a morning to grab a picture of the hoar frost before it melts.
All the focus recently has been on the Arctic sea ice minimum, but the real news to my mind is in the Antarctic, where a recent late crash in sea ice extent has brought forward the date of maximum extent (18.518 million square kilometres [MSK]) for 2016 to the 28th of August, possibly the earliest maximum in the record that began in 1979. The sea ice extent has fallen from the probable maximum on the 28th of August when it stood at almost +1 standard deviation [SD] above the mean, to now very close to -2 SD below the average. I don’t think it’s likely that it can make this ground up and peak again, because the 18th of September is the average time of maximum extent in the Antarctic. Having said that, there was a late surge in sea ice from the 25th of September last year, the surge continued until October 3rd making it the second latest Antarctic maximum, so anything is possible.
In the last couple of days sea ice extents have rallied a little, but the ice extent currently is third lowest for the 18th of September since 1979, at 96.9% of average. As an aside I have decided not to change my software to use a 5 day running mean as the National Snow and Ice Data Center now do. I like the way I do it for one thing, the other reason is that it would be a tricky programming problem to creates a trailing 5 day mean for the whole series, especially when before 1988 values only came in every other day!
It’s not quite reached the minimum sea ice extent in the Arctic but it’s close. The average date for the Arctic minimum is in fact the 11th of September as far as I can see, and looking at the latest figures up until the 7th of September that’s still in doubt, especially as the minima could still occur as late as the 21st (as it did in 1989) which could mean a further two weeks of decline.
Meanwhile 180° south, the Antarctic sea ice is reaching its peak, which if my programming is correct is still 12 days short of the average data maxima occurs on the 19th of September. The increase in sea ice has taken quite a knock in the last 10 days, and at the moment the 2016 maximum has dropped to the 22nd highest since 1979.
Looking at the bigger picture and the rolling 365 day mean since 1989 it’s clear that as the Arctic sea ice has dropped by 14.1% in those 27 years whilst at the same time the Antarctic sea ice has increased by 7.6%, although in the last year that increase has slowed quickly.