Temperature Shenanigans

A week or two ago we were treated to the news that July 2021 was the hottest month on record. Here’s how the BBC had it, as reported by Paul Homewood here:

“July was the world’s hottest month ever recorded, a US federal scientific and regulatory agency [NOAA] has reported.

The data shows that the combined land and ocean-surface temperature was 0.93C (1.68F) above the 20th Century average of 15.8C (60.4F).”

Paul then went on to debunk the story by showing that the month of July 2021 clearly did not have the highest anomaly of any of the temperature series. Here is NOAA’s own graph of temperature anomalies as presented at Notalot, with this July arrowed:

It seemed pretty clear that July 2021 was nowhere near the hottest month on record. I was left scratching my head about this, until it was explained at WUWT. July is the hottest month every year in terms of absolute temperatures rather than anomalies, so a smaller anomaly for July can still result in an overall warmer measure than a higher anomaly in say January. (You might ask why, in that case, we are using anomalies at all; I have no answer to that.)

However, there is more to this story even when NOAA seem to have been proved right in a narrow sense once seasonal signals have been removed from the data. The new anomaly is not just lower than some past months. It’s also lower than at least one past July. That means it’s not a record, right? Was this announcement a straight lie from a US national agency?

Here’s what NOAA said of July 2021:

Note the anomaly: +1.67 F (BBC said +1.68 F, but we’ll let that slide).

Now, here’s what NOAA said in 2019:

Note the anomaly: +1.71 F, which is considered by most people to be higher than +1.67 F.

But (referring to the 2021 statement above) 2019’s record-setting anomaly has since been trimmed from +1.71 F to +1.65 F, making this year’s +1.67 F the new world record. Hooray! We’ve got there. Someone better phone 2019 and ask it to return its gold medal: it’s now in a three-way tie for silver.

Note that I do not imply any nefariousness on the part of NOAA’s data crunchers here. It just isn’t a good look if a record can be silently cancelled, allowing a subsequent lower score to be later announced as yet another record.

Acknowledgement: I first saw the anomalies for 2021 and 2019 compared at Retraction Watch here. I can claim no credit for spotting the difference.


  1. Jit, it doesn’t matter where you found the information, it’s still a great find. I had my suspicions when I noticed that the “record” “beat” the previous record by just 0.01C, which I surmised was so well within the error bands as to make it a highly dubious “record”.

    Not that it stopped the BBC and the Guardian screaming it from the rooftops. It’s interesting to contrast their behaviour in not setting bloodhounds on the scent to check that it really was a record, against their behaviour in seeking to undermine long-standing records so as to allow new lower “record” high temperatures to take precedence:



    Liked by 2 people

  2. It’s also worth noting Retraction Watch’s comment, based on the question they put to NOAA and the response they received:

    “Of course, in a period of global warming, over time we’d expect the average temperature of the world to, well, warm. But 1.67 is decidedly not greater than 1.71, so either this July was the warmest month on record or it wasn’t.

    We put that question to NOAA’s press office, and got this response, attributed to the agency’s climate experts:

    NOAA National Centers for Environmental Information calculates the global temperature anomaly every month based on preliminary data generated from authoritative datasets of temperature observations from around the globe. The major dataset, NOAAGlobalTemp version 5, updated in mid-2019, uses comprehensive data collections of increased global area coverage over both land and ocean surfaces. NOAAGlobalTempv5 is a reconstructed dataset, meaning that the entire period of record is recalculated each month with new data. Based on those new calculations, the new historical data can bring about updates to previously reported values. These factors, together, mean that calculations from the past may be superseded by the most recent data and can affect the numbers reported in the monthly climate reports. The most current reconstruction analysis is always considered the most representative and precise of the climate system, and it is publicly available through Climate at a Glance.

    Our follow-up question: Any plans to add a note to the July 2019 release, or update it? We’re standing by.”

    It’s worth reading the critical words again:

    “calculations from the past may be superseded by the most recent data and can affect the numbers reported in the monthly climate reports.”

    So no record can be truly relied upon, since previously reported values can always be updated. As Jit says, it’s not to imply any nefarious activity here. On the other hand, once NOAA realised (due past calculations being superseded by more recent data) that 2019 wasn’t the record that the headlines had screamed, perhaps a formal retraction issued to the world’s MSM, the same media that had screamed the 2019 headline from the rooftops as part of “climate crisis” hysteria, might have been appropriate? So why didn’t that retraction happen? Could it be that NOAA is as invested in seeking to up the ante regarding “climate crisis” data as is the Guardian and the BBC?

    Liked by 1 person

  3. So we are in the stage of social madness where “just making up crap” passes for “science”, as long as the made up crap is authoritative. .

    Liked by 1 person

  4. Mark, I considered adding NOAA’s explanation, but as it made no sense to me I left it out. The key point seems to be that the past is not fixed, and that therefore old higher values can be reduced, allowing new lower values to exceed them.

    It does work the other way, however. The July 2021 bulletin said that the new value of +1.67 F was +0.02 F over the previous record, “2016, which was then tied in 2019 and 2020.”

    +1.67 F for 2021 beating 2016 by +0.02 F implies 2016 was +1.65 F. At the time, a new record, it was reported as +1.57 F. So it has since been revised UP 0.08 F.

    2019 we already know about:

    +1.67 F for 2021 beating 2019 by +0.02 F implies 2019 was +1.65 F. At the time, a new record, it was reported as +1.71 F.

    +1.67 F for 2021 beating 2020 by +0.02 F implies 2020 was +1.65 F. At the time, NOT a new record, it was reported as +1.66 F. It could have been declared a record, depending on which iteration of the dataset shoved 2019 down 0.06 F.

    Key seems to be that the scale of the revisions far exceeds the increment of the records.

    Hunterson, I see no reason why the past should be so malleable. The temperature was what the temperature was. How do new measurements affect the old?


  5. JIT, is this a rare case of inverse entropy: where disorder increases in the past?


  6. JIT,
    My comment was meant to completely underscore the obvious answer to the excellent question you asked.
    If we were facing an objectively *real* crisis, no one would tolerate the arm waving and ex-post facto bs that passes for “climate science”.
    To use one of the favorite arguments of the consensus regarding insurance: if the insurance agent were even possibly selling a phony policy based on scary scenarios made up profitably by the insurance agent, why would we not as insurance purchasers not want to at least have a serious look at what the agent was claiming?


  7. The result is two bites of the PR cherry
    They got publicity in July 2019
    An they got publicity in July 2021
    when if 2019 had been accurate in the first place the wouldn’t have .

    BTW I think Global Average temperature is a BS metric
    On a simplistic scale it gives us some trend spotting
    but it’s not even that valid
    Just cos one place in 2021 is warmer than 2020 that doesn’t automatically mean greta Global Warming
    Actually in 2021 that pattern of dominant winds will be different to 2020 etc

    We might live on a farm in Aberdeenshire one year
    and in on a farm in South of France the next year
    what’s it matter if grow enough to live and can cope with bad weather ?


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