Monday, September 09, 2013

Nice graphic

Arctic sea ice delusions strike the Mail on Sunday and Telegraph | Dana Nuccitelli | Environment | theguardian.com

The Arctic Sea Ice extent minimum, which is only a short time off, is going to be much higher than last year's record, but as noted in the above article:
As University of Reading climate scientist Ed Hawkins noted last year,
"Around 80% of the ~100 scientists at the Bjerknes [Arctic climate science] conference thought that there would be MORE Arctic sea-ice in 2013, compared to 2012."
The reason so many climate scientists predicted more ice this year than last is quite simple. There's a principle in statistics known as "regression toward the mean," which is the phenomenon that if an extreme value of a variable is observed, the next measurement will generally be less extreme. In other words, we should not often expect to observe records in consecutive years. 2012 shattered the previous record low sea ice extent; hence 'regression towards the mean' told us that 2013 would likely have a higher minimum extent.
And this is nicely illustrated by this lovely gif, which I don't think I have seen before:

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