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NOAA Confirm UAH Tropospheric Temperature Trends

April 13, 2023

By Paul Homewood

h/t Joe Public




An important new study on climate change came out recently. I’m not talking about the Intergovernmental Panel on Climate Change (IPCC) Synthesis Report with its nonsensical headline “Urgent climate action can secure a liveable future for all.” No, that’s just meaningless sloganeering proving yet again how far the IPCC has departed from its original mission of providing objective scientific assessments.

I’m referring instead to a new paper in the Journal of Geophysical Research-Atmospheres by a group of scientists at the U.S. National Oceanic and Atmospheric Administration (NOAA) headed by Cheng-Zhi Zou, which presents a new satellite-derived temperature record for the global troposphere (the atmospheric layer from one kilometre up to about 10 km altitude).

The troposphere climate record has been heavily debated for two reasons. First, it’s where climate models say the effect of warming due to greenhouse gases (GHGs) will be the strongest, especially in the mid-troposphere. And since that layer is not affected by urbanization or other changes to the land surface it’s a good place to observe a clean signal of the effect of GHGs.


Since the 1990s the records from both weather satellites and weather balloons have shown that climate models predict too much warming. In a 2020 paper, John Christy of the University of Alabama-Huntsville (UAH) and I examined the outputs of the 38 newest climate models and compared their global tropospheric warming rates over 1979 to 2014 against observations from satellites and weather balloons. All 38 exhibited too much warming, and in most cases the differences were statistically significant. We argued that this points to a structural error in climate models where they respond too strongly to GHGs.

But, and this is the second point of controversy, there have also been challenges to the observational record. Christy and his co-author, Roy Spencer, invented the original method of deriving temperatures from microwave radiation measurements collected by NOAA satellites in orbit since 1979. Their achievement earned them numerous accolades, but also attracted controversy because their satellite record didn’t show any warming. About 20 years ago scientists at Remote Sensing Systems in California found a small error in their algorithm that, once corrected, did yield a warming trend.

Christy and Spencer incorporated the RSS correction, but the two teams subsequently differed on other questions, such as how to correct for the positional drift of the satellites, which changes the time of day when instruments take their readings over each location. The RSS team used a climate model to develop the correction while the UAH team used an empirical method, leading to slightly different results. Another question was how to merge records when one satellite is taken out of service and replaced by another. Incorrect splicing can introduce spurious warming or cooling.

In the end the two series were similar but RSS has consistently exhibited more warming than UAH.  Then a little more than a decade ago, the group at NOAA headed by Zou produced a new data product called STAR (Satellite Applications and Research). They used the same underlying microwave retrievals but produced a temperature record showing much more warming than either UAH or RSS, as well as all the weather balloon records. It came close to validating the climate models, although in my paper with Christy we included the STAR data in the satellite average and the models still ran too hot. Nonetheless it was possible to point to the coolest of the models and compare them to the STAR data and find a match, which was a lifeline for those arguing that climate models are within the uncertainty range of the data.

Until now. In their new paper Zou and his co-authors rebuilt the STAR series based on a new empirical method for removing time-of-day observation drift and a more stable method of merging satellite records. Now STAR agrees with the UAH series very closely — in fact it has a slightly smaller warming trend. The old STAR series had a mid-troposphere warming trend of 0.16 degrees Celsius per decade, but it’s now 0.09 degrees per decade, compared to 0.1 in UAH and 0.14 in RSS. For the troposphere as a whole they estimate a warming trend of 0.14 C/decade.

Zou’s team notes that their findings “have strong implications for trends in climate model simulations and other observations” because the atmosphere has warmed at half the average rate predicted by climate models over the same period. They also note that their findings are “consistent with conclusions in McKitrick and Christy (2020),” namely that climate models have a pervasive global warming bias. In other research, Christy and mathematician Richard McNider have shown that the satellite warming rate implies the climate system can only be half as sensitive to GHGs as the average model used by the IPCC for projecting future warming.

  1. Nigel Sherratt permalink
    April 13, 2023 10:06 am

    Encouraging news, Christy and Spencer have taken a lot of heat including actual gun shots (on Earth Day 2017).

    Monckton’s analysis of gain including the neglected input from the sun (Hansen’s fundamental error) shows much reduced sensitivity too (from 10:00).

  2. Johnnbuchanan permalink
    April 13, 2023 10:37 am

    Dear Paul My group, the Canadian International.Council, is hosting a talk by Ross McKitrick on May 3 in person in Montreal and by Zoom/Youtube. A copy of the content is attached. Would you be interested in promoting and perhaps attending the event by Zoom? I look forward to hearing from you. Thank ypu for all of your efforts to promote the truth!! John Buchanan

    Sent from AOL on Android

  3. April 13, 2023 10:40 am

    Could emergence from an ice age not be the basis of any such presnt warming trend as found at UAH?

    • bobn permalink
      April 13, 2023 11:31 am

      Now dont be logical.
      How radical to think that climate may go in cycles and not be constant; as climate was created 6000yrs ago in the garden of Eden to be never changing – or thats what Greta and the XR loonies think!

      • April 13, 2023 12:37 pm

        Indeed! Strange how we are told climateageddon (without any supporting evidence) is upon us now because of “shocking” and “unprecedented” temperature increases due solely to man’s use of hydrocarbons. What good have hydrocarbons ever done for us! We are told this repeatedly with without any qualification or reference to the Minoan warm, the Roman warm or the Medieval warm. This is interesting in light of archaeological evidence which shows that figs were grown in Cambridgeshire during the Roman warm and documentary evidence that grapes were grown openly in Yorkshire during the Medieval warm, two things which are not possible today because it is not warm enough.
        Strange therefore to be told it has never been “hotter” than today and that the pwannet will boil away into space “unless” we prostrate ourselves and comply unquestioningly with Marxist Leninist dictats. Also strange that when a global phenomenon is claimed, the focus of this endeavour is solely on the developed Western World ignoring the greatest and increasing emitters of the carbon “poison”. Any attempt to counter or question the “settled science” with actual science results in the unwary being screamed at and accused of hate speech and racism by the arts degreed experts in climate “science”. A better example of a politically manipulated religion it is not possible to find.

    • Phoenix44 permalink
      April 13, 2023 12:36 pm

      I’m not convinced it’s a “trend” as such. There’s no consistent warming but a series of step changes. Lots of mechanisms can explain that and a random walk with some chaotic properties can replicate it. Modern science loves to draw straight lines and claim trends but often its just random.

  4. ThinkingScientist permalink
    April 13, 2023 11:46 am

    Glad to see further support of UAH6 from NOAA. Climate4you has always rated UAH as the most consistent measure of global temperature due to its stability over time and lack of arbitrary changes (such as occurred with RSS).

    It has always been my view that UAH6 is the most reliable temperature time series and that seems to have been vindicated with this new paper.

    So next time I am arguing about choice of temperature series there is further support for choosing UAH6. And for referring to Christy’s work showing how models are exaggerating warming. Good news.

    • April 13, 2023 12:41 pm

      I look forward to seeing this as a headline tomorrow on the “impartial” BBC web page…….

  5. Phoenix44 permalink
    April 13, 2023 12:39 pm

    Yet more evidence the models run far too hot. At low ECS, there is literally no reason to do anything now. The climate will slowly warm until we find sensible alternatives to CO2 emitting activities.

  6. April 13, 2023 2:40 pm

    The planet is always either warming or cooling at climate-scale periods to some extent. It’s obvious from the fact that there’s plenty of evidence showing glaciers have advanced and retreated multiple times over the centuries.

  7. April 13, 2023 2:55 pm

    It was Ross McKitrick and Steve McIntyre who uncovered the Mann et al. hoax at UEA w/ the IPCC debacle.

    • Joe Public permalink
      April 13, 2023 5:09 pm

      That (together with Climategate emails) led to my Damascene Conversion away from absolute ‘trust’ in scientists’ pronouncements.

      • April 14, 2023 11:59 am

        When I hear, “experts say” or “scientists say” I am always asking “what are their credentials?” What is the background for that statement???

        We have a local yokel here who passes himself off as an environmental scientist when running for office. However, he is an engineer and I believe a computer engineer. He IS NOT a scientist and has absolutely no background to pass as an environmental one. However, as a far left guy, he is not pushed back on very much.

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