The Arctic sea ice extents still doesn’t seem to be following the script that most people have prepared for it so far this Spring. In the last fortnight it’s still been making ground up on the -2 SD line, and on the 28th of May, was only the 6th lowest for that particular date in the 39 year-long series (fig 1). The sea ice is now just 5% below the long-term average for this date, and I’m sure some people are arguing that the extent has changed little since 1995, even though it maybe a lot thinner.
Figure 1 – Data courtesy of the NSIDC
Meanwhile in the Antarctic, the sea ice is following the script and is the third lowest for the date of the 28th May, and 10% below the long-term average.
I’ve just been projecting forward the sea ice extent using the statistics the data that I download from the NSIDC. I’ve used the rate of change of the 10th percentile, and applied it from the 16th of April running forward (fig 1) to the extent on that day. If these projections are correct, I reckon that the Arctic summer minimum will be around 3.7 million square kilometres. This is the only the second time Arctic sea ice will have ever fallen under the 4 million level mark in the satellite series, that should happen at the start of September, which is what it almost managed to do last year. I’m sure a lot of people are looking at a much lower minimum, but the Arctic has put on a bit of extent this Winter, after suffering substantial losses during the run up to Christmas.
Rather more severe is the Antarctic projection for their upcoming Winter. I see the maximum at around 15.8 million square kilometres in the second week of September, the previous lowest maximum extent was 17.803 at the very start of the satellite series in 1978 (fig 2), so this figure is seriously low if it comes about. This year (the red line) will track much lower than 2017 (the black line), if anything the gap will widen between the two if anything, this is because up until the 28th of August last year the Antarctic was doing very well, with the extent slightly above average, but after that date the extent suddenly collapsed in September when it should really have been peaking. So I reckon that all eyes might be on the Antarctic this September, rather than the Arctic.
I will revisit these projections in September, it maybe by then, that I’ll have some serious egg to wash of my face, who knows my projections could end up being optimistic!
I will be the first to admit that what I’ve done is not scientific in any way, it’s just playing with the statistics of the last 40 years, but what the hell.
Figure 1 – Courtesy of the NASA Goddard Space Flight Center
There’s a lot of fear and apprehension going about on the Internet about the current state of the polar sea ice extent. I’ve always kept a close eye on how it’s performing both in the Arctic and Antarctic over the past 5 years with the help of the NSIDC, certainly in the Antarctic sea ice has fluctuated wildly in the past few years, but in the Arctic it’s been more or less just down. The latest data for the 14th of April is at a record low for this time of the year (fig 2), but it’s only slightly worse than at the same time in 2007. Perhaps the quality of the ice cap in the Arctic is thinner that it has been in the past, and maybe once it reached a critical ‘thinness’, then the extent will just crash one of these summers.
I’ve added a curve fitting series to both graphs, rather than just my usual linear trend which doesn’t lend itself to the Antarctic data at all well. The Antarctic curve is showing signs of taking a nose dive at the moment, because of the massive decline in the sea ice extent in the last few seasons (fig 3).
This graph of the Arctic sea ice volume anomaly (fig 4) does lend itself to a linear trend. Perhaps PIOMAS is a better way of looking at sea ice extent than the SII is, I don’t really know.
And just to give the full perspective on my earlier graph of the Arctic sea ice extent.
Now that we’ve seen both the lowest Arctic sea ice maximum and the lowest Antarctic sea ice minimum records broken this year, the two big questions regarding Polar sea ice are:
- How low can the Arctic sea ice minimum get this summer?
- Can the Antarctic sea ice bounce back this winter after such a catastrophic melt in the summer?
The Arctic rallied towards the end of this Winter but the 14.447 still couldn’t quite match the previous lowest maximum of 14.554 million square kilometers set on 22nd of February 2015. So just by looking at the stats, it seems that this summer may push the minimum of 3.34 million square kilometers of September 16th 2012, but the minimum that year was abnormally low even for the Arctic, and may take some beating.
The Antarctic sea ice on the other hand is starting the year extremely low at 2.075 million square kilometers. It will be interesting to see if it can catch up, but that’s a tall order, and this winter we might see a record low maximum, the previous lowest maximum was 18.027 million square kilometers set on September 18th 1986.
The end of Arctic sea ice in summer is still a long way off as far as I can see. A simple linear trend on each years minima puts zero summer sea ice in 2066. I’ve tried another type of polynomial line fitting curve but I can’t extrapolate a forecast from that, so that’s my best guess at the moment.
It’s make or break in the next couple of weeks for Arctic sea ice, the rally it’s been staging since the middle of January has faltered, but today’s value (4th March) is it’s maximum extent this season, and it’s now within 120,000 square kilometres of the lowest maximum year of 2014-15. Last years Arctic maximum occurred very late on the 21st of March, so there is still time for it to make up this shortfall.
Meanwhile in the Antarctic summer, I would say that we have now have seen the minimum ice extent this year (on the 1st of March), which as well as being the lowest in the series since 1978, was also the second latest minimum, the average date for that is the 20th of February. One thing the sea ice extent did manage was to stay above the 2 million square kilometre mark, but only just. It will be interesting to see if the sea ice extent continues to spiral down in the coming season or if it will manage to stage some kind of recovery.
Figure 1 – Data courtesy of NSIDC
It’s always been a question of when, rather than if the Antarctic sea ice extent record would be broken this season, but finally the 2.246 million square kilometres for the 12th February (fig 1), has dipped just a fraction lower than the 2.264 of the 22nd of September in 1997, to break the lowest minimum record in the satellite series that started in 1978. Earlier in the season it looked like the extent would be as much as 30% below the long-term minimum, but the decline did slow, and at the moment (12th February) it’s only 25.8% lower than average for that date. The decline in Antarctic sea ice is even more spectacular, considering that it was just over two years ago that they were at record high levels (fig 2), and the decline is set to continue for another four weeks before the minima is reached, so a sub 2 million minima is a distinct possibility.
Figure 2 – Data courtesy of NSIDC
I notice that the National Geographic were able to do an article about the record yesterday even before the figures were released by the NSIDC, which is fair enough, because if it wasn’t for the Americans, there wouldn’t be a SII anyway. And finally, here is this season overlaid on the previous 38 or so, to put it into some kind of perspective (fig 3).
Figure 3 – Data courtesy of NSIDC
Figure 1 – Data courtesy of NSIDC
The Antarctic sea ice extent at the moment, is hovering fractionally above the record lowest extent of 2.264 million square kilometers that occurred on 27 February 1997. I’ve been watching it over the last few weeks but the decline has now flattened as the Summer minima approaches in the next couple of weeks. The Antarctic minima occurs on average around the 20th of February, so there is still plenty of time for a final dip, although I still can’t believe just how much improved the extent looks now than it did a month or so ago.
Figure 2 – Data courtesy of NSIDC
Todo: Check that average it looks a bit lopsided.
Image 1 – Arctic Sea Ice (22 Jan 2017) Courtesy of the NSIDC
I thought that I’d just have a peek and see how the Arctic Sea ice was doing by downloading the latest MAISIE and Arctic SII from the NSIDC. Here’s an inter-comparison chart of the last years data from them both.
Figure 1 – Data courtesy of the NSIDC
I’ll warn you, because of the way that they are calculated, the SII always produces a higher estimate than MAISIE does during Winter, but apparently, according to what I read MAISIE is more accurate during the Summer.
The NSIDC have just rejigged all their data files since the New Year, in fact they’ve simplified them quite a bit, but it did catch me on the hop. But with a quick rewrite I think things are now back to normal. They have also included in their download files long-term daily values for the 10th, 25th, 50th, 75th and 90th percentiles, which I have now incorporated into the comparison chart (fig 2). Winter 2016/17 continues to mend in fits and starts, and for the latest values on the 22nd of January has climbed off the bottom of the table for the first time since October, with a marginally better sea ice extent for this day than in 2006. So although Arctic sea ice is in much better shape than it was in late Autumn, the extent on the 22nd of January is still only 91.9% of the long-term average for that day.
Figure 2 – Data courtesy of the NSIDC
Meanwhile in the Antarctic, I can’t for the life of me see why Summer 2016/17 isn’t going to go down as the lowest minimum since these satellite records began in 1978. An amazing turnaround from just a couple of years ago when there were records amount of Antarctic sea ice, but looking at recent temperature anomalies, I can now see why.
Courtesy of NASA
I saw this article on the BBC and thought you should see it: Larsen ice crack continues to open up.
Image 1 – Courtesy of AARI/NIC/NMI
Image 2 – Courtesy of Wikipedia
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!
Image 3 – Data courtesy of NCEP