UPDATE, It appears that my post uses data published yet not recommended by Phil Jones. Perhaps a retraction by Dr. Jones is in order or is it as Lucia points out in her post, a case of white noise.

### Douglas J. Keenan

in comments below notes:

Here is a quote from that: “global and regional time-series should be calculated using unadjusted data”. Indeed, the authors have criticized others for attempting to use HadCRUT3v for time series. Note that Jones is one of the authors.

Here is the full quote:

Whether variance adjusted or unadjusted data should be used in an analysis depends on what is to be calculated. If it is necessary that grid-box anomalies have a spatially and temporally consistent variance, then variance adjusted data should be used. Otherwise, better results may be obtained using unadjusted data.

In particular, global and regional time-series should be calculated using unadjusted data.

The barely significant adjusted data should NOT be used for trend analysis per Dr. Jones himself. Will climate wonders never cease.

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Phil Jones made a few famous quotes around the time of climategate. One of them was brought up again in a happy correction to the record as reported by the BBC on June 10th. Lucia covered it here already. Back a year and a half ago, Phil let slip in an unusually difficult interview for a climate scientist that there was no statistically significant warming since 1995.

B – Do you agree that from 1995 to the present there has been no statistically-significant global warmingYes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.

This refers to the arbitrary yet regularly used 95% threshold or 1/20 chance that the result happened by accident alone. Now in a new article Phil reports this:

Climate warming since 1995 is now statistically significant, according to Phil Jones, the UK scientist targeted in the “ClimateGate” affair.

Yay!! We all knew it was coming, because as the data record grows longer even in a temperature stable world, statistical thresholds are naturally crossed. The Earth would have to cool quickly in order to prevent this threshold from being crossed. We discussed the issue in 2009 here, just days prior to climategate.

Lucia took the annual averages and corrected she for AR1 (autocorrelation), she found that the claim by Jones was still invalid. Well, that caught my interest so I looked more closely at the data and wrote a downloader for the monthly HADCRUT3 and HADCRUT3V data in R. I then dug up some old algorithms and did some of my own plots. HADCRUT3 is a simple gridded version of the temperature data where anomalies are combined by grid and averaged. HADCRUT3V has some sort of variance adjustment as described by Jones 2001, which ‘corrects’ the variance. I have not read or looked for the paper and so cannnot comment on its veracity.

I made the following plot using the code below. This uses all the available data, calculates a trend and a confidence interval for that trend based on the Quenouille AR1 degrees of freedom correction. Nothing too magical about that. The red lines are the +/- confidence interval, the black line is the slope of the data in C/Decade for each month to the most recent month. In other words, I fit a slope for the data from every month in history starting with 1980 January to present,, 1980 February to present, March etc, all the way until 2008 because a slope for three years of global temperatures is silly.