Friday, September 16, 2016

Arctic ice freezing, Antarctic melting

As many have now noted, Arctic sea ice stopped melting rather abruptly after 6 September, and has lately been freezing quite rapidly. The pattern is quite similar to last year, but a few days earlier. In both JAXA and NSIDC the minimum was lower than 2007, but higher than 2012, so in secoind place (but in NSIDC, only just).

Meanwhile, more surprisingly, Antarctic ice has been melting strongly for six days, and now stands below the other years of this century at least, for this time. From the radial plot here, I'll show the NSIDC plots for recent days. The plot spans most of September.


The red curve is 2002. Orientation same as NH.


  1. Very interesting, but why are the Antarctic traces so much smoother than the Arctic traces? Is it simply that you are zooming into a higher resolution on the scale for the Arctic?

    I have read that some people suggest there may be alternating polar oscillations over periods of 30 to 60 years such that when the Antarctic warms, the Arctic cools, and vice versa, possibly from some kind of ocean circulation effect that takes a long time to operate. We certainly don't have a long enough record of high quality data yet to be able to evaluate this hypothesis very well, but time will tell.

    1. Bryan,
      Well, I'm not smoothing them; the numbers as plotted are tabulated and plotted as reported. But it may be because the SH winter ice has open ocean frontage, while NH ice has all sorts of land features and currents - bays that melt (or freeze) together, straits where a wind can wash ice away. Or possibly even that the land just causes some measurement confusion.

  2. Bryan,

    I dont think there is an oscillations of periods of 30 to 60 years. But a connection between them is very possible but would be more on times, when the is massiv and aprrupt fresh water impuls in the north atlantic, which is able to shut down the AMOC, then arctic cools while antartica warms, we saw this in the holocence (dont know the exact date but should be known as 8.2K-Event or so), as north americas ice had produced a massive fresh water impuls.

  3. Ice extent is an insufficient proxy for assessing the short-term dynamics of the arctic ice. If you examine satellite imagery of the arctic (MODIS, for example) over the past few weeks, you can see that the real culprit in extent reversal was not re-freezing (though there was likely some), but rather the dramatic fracturing of the ice just north of the Canadian Archipelago. Those massive cracks suddenly increased the extent in the Central Arctic Basin due to expansion of ice extent via fissuring; and sent ice floes into the CA and Greenland Sea, via transport (also increasing extent). More of that ice will meet its demise if the weather encourages further transport to warmer waters. Long story short, though the extent may be increasing, the ice has still been getting hammered.