Comments 1 to 6:

1. One Planet Only Forever at 15:03 PM on 3 August, 2021

   Checked Dr. Roy Spencer's update for the July UAH global average.

   He has a new twist for presenting data to make it appear as though the current numbers as not unusually high. He has shifted all the data to be lower relative to the zero line. And he helpfully provides the following:

   "REMINDER: We have changed the 30-year averaging period from which we compute anomalies to 1991-2020, from the old period 1981-2010. This change does not affect the temperature trends."

   If the change does not affect the presentation of the temperature trends then - Why was it done? Probably to try to make things appear more like he wants them to appear.

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2. Eclectic at 16:55 PM on 3 August, 2021

   One Planet,

     it really doesn't matter much, which baseline Spencer uses - since his main monthly publication site seems to be on the WattsUpWithThat*  blog.

   *Where "The Error-Prone Viscount" ( as science journalist Potholer54 terms Lord Monckton)  has already posted another global temperature has paused for 6 years now . . . as per usual.

   It is a pity - and absolutely quite inexplicable - that WUWT  doesn't ever publish the Spencer UAH TLT graph overlaid with the RSS graph of TLT temperatures.

   The WUWTers are frequently complaining how climate scientists mislead the ordinary public by giving temperatures as temperature anomaly figures instead of expressing a real Celsius temperature.  Perhaps we can persuade Dr Spencer to chart his UAH TLT temperature figures in simple Celsius figures - where the TLT baseline is about Minus 26C .  (If I have correctly understood commentary at RealClimate blog.)

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3. MA Rodger at 00:41 AM on 4 August, 2021

   One Planet Only Forever @1,

   You ask about the change in anomaly base to 1991-2020 "Why was it done?"

   The deniers at UAH are not alone in making this change. Both Copernicus and NOAA have made this same change although GISTEMP LOTI continue with 1951-80 as an anomaly base. The change comforms with the WMO who ruled in 2017 (see page 2 here) that "the definition of a climatological standard normal ... now refers to the most-recent 30-year period finishing in a year ending with 0 (1981–2010 at the time of writing)."  Mind, they do add, "However, the period from 1961 to 1990 has been retained as a standard reference period for long-term climate change assessments." So the correct choice isn't actually written in stone.

   The choice of anomaly base does make a difference when, say, looking at monthly anomalies through a year when there is a change in the annual cycle. Thus in UAH, throwing an OLS through each individual month shows a warming of +0.115ºC/decade for June but +0.163ºC/decade for September.

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4. One Planet Only Forever at 02:50 AM on 4 August, 2021

   MA Rogers,

   Thanks for the info about the WMO.

   As a structural engineer I am infinitely familiar with the 10 year update of climate design data based on the most recent complete 30 years ending in a Zero.

   And maintaining a consistent basis for presentation of climate change information rather than updating all of it every 10 years is logical.

   So it appears that the change Dr. Spence made is likely intentionally misleading - no real good reason likely able to be provided.

   btw, NOAA do not appear to have implemented 1991 to 2020 as their updated baseline. The NOAA page I go to for temperature data still says  "Please note, global and hemispheric anomalies are with respect to the 20th century average. Coordinate anomalies are with respect to the 1981 to 2010 average. All other regional anomalies are with respect to the 1910 to 2000 average."

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5. One Planet Only Forever at 03:11 AM on 4 August, 2021

   Eclectic, It would indeed be amusing to hear the WUWT crowd, especially Dr. Spencer and "The Error-Prone Viscount", attempt to present a rational solid argument justifying not presenting the real satellite data TLT temperature values.

   The -26C baseline value for the average TLT makes sense. But the large negative value would trigger questions that could scramble the cognitive dissonance into a flurry of fuzzy attempts to dismiss the clear evidence that satellite data averages are not to be considered to be a rational replacement for the surface temperature averages.

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6. michael sweet at 21:32 PM on 9 August, 2021

   This First Dog on the Moon cartoon would look good on Skeptical Science.

   (Sorry, I could not get the cartoon to copy to post it here)

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