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When was the last time this happened?

August 4, 2013

We are in the middle of the Arctic melt season.  The rate of sea ice melt is at it greatest from about mid-June (day 156) to about mid-August (day 216).  Thirty years ago, according to satellite data, the arctic lost about 5 million square kilometers of ice during this period.  For the last decade the arctic has lost closer to 6 million square kilometers of ice during this period.  That averages out to about 100,000 kilometers per day.  Of course, it recovers all, or most, of that area during the freezing season.  This point is illustrated in the follow image from Cryosphere Today (8/4/13, with my annotation).

Northern Hemisphere sea ice area 5

Now look closer.

Northern Hemisphere sea ice area 4

Notice that for the last 10 days there has been no drop in sea ice area. We would have expected a loss on the order of one million square kilometers!  Either something extraordinary is happening, or there is a problem with the satellite data.

When was the last time this happened this time of year?  This image shows the entire history of the arctic (which everyone knows really means back to 1979).  This is “unprecedented!”

One comment

  1. And no comments from the peanut gallery.



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