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Global Temperature Update–October 2012

November 22, 2012


By Paul Homewood


All the four main datasets have now been released for October.


October 2012 Anomaly 0.29 0.34 0.52 0.69
Increase/Decrease From Last Month -0.09 0.00 0.00 +0.08
12 Month Running Average 0.18 0.13 0.43 0.51
Average 2002-11 0.26 0.19 0.47 0.55



RSS are down, HADCRUT and UAH are unchanged and GISS is up. Is anyone surprised about that?

The 12 month running averages all remain below the 10 year average, even GISS. My guess is that the UAH figures for the year will finish at about 0.17C, as the cooler La Nina affected months of November and December 2011 disappear from the calculations. In this case, 2012, would end up being the 4th coldest year in the last ten.

For devotees of the “warmest decade evuh”, it is worth noting that the start to the new decade, i.e 2011/12, is running cooler than the 2001-10 period. I wonder what their next bolt hole will be? Hottest 12 year period evuh?


Let’s finish by looking at the graphs.







Monthly anomalies are shown in blue, while the red lines are the centred 12-month running averages. (For instance, the 12 month average for Jan-Dec 2011 appears in June 2011.)

None of the sets suggest that temperature trends have done much in the last ten years.



1) The baseline periods used for calculation of anomalies is different for each set, so direct comparisons are not possible. The baselines used are :-

RSS – 1979-98

UAH – 1981-2010

HADCRUT – 1961-90

GISS – 1951-80


2) Sources




UAH have revised their number upwards from 0.33 to 0.34, which I have now amended.

  1. Ray permalink
    November 22, 2012 3:26 pm

    I’m just wondering why you don’t include NCDC/NOAA in your analysis?
    That also fell in October, making GISS look even more of an exception.

    • November 22, 2012 3:54 pm

      Yes, that’s interesting Ray. In theory, GISS land temperatures are based on the same GHCN data as NCDC (and it seems to be land temps that have diverged this month).

  2. David permalink
    November 22, 2012 5:54 pm

    Please note, the UAH officially published anomaly for October 2012 has been raised to +0.34C: This means the change from last month is now 0.00C for UAH.

    • November 22, 2012 6:52 pm

      Thanks, David. They even sometimes change last year’s!

      I’ve amended now.

      • David permalink
        November 25, 2012 10:08 pm


        I also think your comparison table would benefit if you adjusted all the sets to just one anomaly reference period. For example, if you adjust everything to UAH (1981-2010), then the ‘average 2002-2011’ row becomes:

        RSS: 0.16
        UAH: 0.19
        HADCRUT 4: 0.22
        GISS: 0.20

        Instead of the apparently large differences between the data sets that your current table suggests over the past 10 years, we see that, adjusted to a common reference period, they all agree to within a few 1/100ths of a degree.

        I’m sure you would not wish your readers to be misled into thinking that there is any major discrepancy between the various data sets over the last 10 years.

      • November 25, 2012 11:14 pm

        I showed a similar graph last month. Although there was not a huge difference between the four sets, it was noticeable that GISS began to diverge significantly after around 1998.

        For instance, RSS give 0.461 in Oct 98 falling to 0.294 last month – a reduction of 0.167C. GISS though show an increase from 0.410 to 0.680C, = 0.270C. So a net turn around of 0.437C . Pretty significant I am sure you would agree.

        Taking the 12 month averages, GISS still show 0.15C more warming since 1979 than GISS, i.e about a third of their total warming.

  3. November 23, 2012 4:34 am

    This is off topic, but you may be interested to know how thick the ice is on the east side of the Antarctic this year. The Australian icebreaker Aurora Australis got stuck in the ice for three weeks. They reported on Nov 5 that the ice was an average of 6m thick and between 15 and 20m in places. Note: At the time they were a long way from shore.

    They have since returned to Hobart and are on a return voyage. Getting stuck for so long cost a lot of money, and they may have to some other program for this season.

    From the ship log:
    “We are slowly heading towards the open lead only 500m ahead of us. It’s incredibly slow going ramming back and fore into ice that’s an average of 6m thick, and between 15 and 20m in places.

    Since leaving ice station 8 yesterday evening we have managed 250 rams and made about three ship lengths (300m). If we’re lucky the last hundred or so meters will peel off when we get closer, releasing the ship at last. “

  4. Kev-in-Uk permalink
    November 23, 2012 1:44 pm

    Just a thought regarding the recent lack of warming, which I am sure someone else will have considered: In essence, I am thinking about UHI, which we all know affects the urban area records and the effect rose as urban sprawls explanded, etc, etc. However, I am wondering if anyone has considered the subsequent effect upon the UHI effect of the fuel ‘efficiency’ drives of the 80’s and 90’s. I have heard/seen warmist types claiming that the lack of warming proves UHI is ‘minor’ – but of course if you have a governments promoting insulation and fuel efficiency, etc – this will probably mean ‘net’ UHI effect staying the same, despite increased population/city growth?
    I am wondering if anyone has had a stab at linking fuel ‘efficiency’ or ‘use’ over the last 15-20 years?

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