The last 10 years (120 months) are 0.21°C warmer than the preceding 10 years (120 months).
As he does every month, Roy Spencer includes a 3rd-order polynomial fit for the data, "for entertainment purposes only":
Why 3rd-order? Perhaps because here's what the 6th-order fit looks like:
Notice that little hike upward there at the end.... And actually a 6th-order fit has a better correlation coefficient than does the 3rd-order fit:
R2 (3rd-order fit) = 0.3901
R2 (6th-order fit) = 0.3951
What does Spencer's fit "predict" for the future?
Jan 2050: -5.8°C
Jan 2100: -50.2°C
Those are some entertaining "predictions" -- the "planet" at the end of this century "will have" an average temperature of "-33°F." Naturally the commenters at WUWT are excited about Spencer's fit because they think it's starting to show a downward trend.
By the way, the 10-year slope of the UAH global LT data is 0.032 ± 0.049 °C/decade. Notice it's not negative.
Aren't statistics fun? They can say so many different things, all at the same time....
3 comments:
> a 6th-order fit has a better correlation coefficient than does the 3rd-order fit
But you expect that anyway; you're allowing more parameters, so you get a better fit.
There is a proper statistic-y way of accounting for this, but I forget it. DC will know :-)
funny. i always thought it would be more "entertaining" to use a linear fit
It is not quite the thing I was thinking of, but http://tamino.wordpress.com/2012/01/09/steps/ discusses the same issue: that more params leads to a better fit, but may not be a better model. See AIC, there.
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