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Alan Clark
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The plural of phenomenon is phenomena. Apart from that, a great article.
Wipneus: If you did the calculations with only the data from, say, 2000 I think you would find that the standard deviation is less (although the set is now rather small). The year 2007 is supposed to be an exceptional year, and yet it is only ~1.5 SD below the trend, which indicates that there is room for improvement in the way the algorithm calculates the variability. Probably not worth worrying about it too much though!
An observation about the last of the graphs at the top (minimum ice volume): in recent years the points are mainly within 1 Standard Deviation of the trend line, and never much more. However, in the earlier years there are many points which are well over 1 SD from the trend line. This means that the variation is getting smaller in absolute terms but not so much in percentage terms (unsurprisingly). So if the trend continues then zero will almost certainly be reached in 2014 or 2015, and the range of possibilities is much less than the graph suggests.
I have been lurking here for some time, but I have just come across this: I don't know how much bearing this has on the discussion.
With the volume of ice shrinking so rapidly I am surprised that anyone would predict a greater extent than September 2010! On that basis (and wishful thinking) I expect the actual value to be lower than all the predictions, about 3.8.
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Jun 17, 2011