Polar sea ice extremes

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xmetman

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Sep 9, 2016, 9:51:53 AM9/9/16
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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.



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.


For more information about Antarctic sea ice follow the link to my blog.

Alastair B. McDonald

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Sep 9, 2016, 10:36:56 AM9/9/16
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Very interesting!

I thought that the Antarctic sea ice extent had recovered from its increase over the last two or three years, but its looks from your chart that the increase goes back to at least 1995 and that this years return to average may just be a blip like that in 2003.

Cheers, Alastair.

xmetman

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Sep 9, 2016, 10:50:29 AM9/9/16
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Alastair

Yes it's quite a staggering decline in Antarctic sea ice, with the 365 day mean falling from over 12.8 Million square kilometres to 11.6 in the last 15 months or so. The Antarctic has seen sharp falls and rises in this time, but none as prolonged as this decline. By the way your posting on UKSW inspired me to post, I was going to do it next week but I thought what the hell.

Bruce.

Alastair B. McDonald

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Sep 9, 2016, 12:05:08 PM9/9/16
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Judging by your chart of Arctic minimum ice dates it seems I may have been a bit premature calling the melt as over for this year. Also your chart shows this year as second lowest already, whereas I had hedged my bets.

I was at a meeting of the Royal Society two years ago about Arctic Sea ice https://royalsociety.org/science-events-and-lectures/2014/arctic-sea-ice/

At the end they summed up the proceedings and ask whether everyone agreed that the Arctic and Antarctic sea ice were declining. I was the only one to point out that the Antarctic sea ice was increasing. That was the day when the Antarctic sea ice reached it greatest extent ever recorded (until then?)

Cheers, Alastair.

John Hall

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Sep 9, 2016, 2:05:02 PM9/9/16
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Those last two charts are interesting. You could argue that there was a clear trend of diminishing sea ice in the Arctic till about 2008, but that since then the variations might conceivably be no more than random noise (about a much lower mean level than hitherto, of course). Meanwhile in the Antarctic, up until 2008 there seems to be no clear trend, followed by a clear upward trend until the very recent sharp decline. The year for the changes in behaviour in both the Arctic and Antarctic sea ice being the same is probably no more than coincidence, and of course the levelling off in the Arctic even if real is almost certain to be only temporary, but I can't help wondering if something significant happened around 2008.

Paul Garvey

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Sep 10, 2016, 7:55:51 AM9/10/16
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Doubt it John. The reasons for ice extent changes at both poles are very different. The only thing that has happened with ice loss in the Arctic is that it is has continued. I don't see that anything significant happened in any one year, including 2008. 
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