Contradictory Contrarian Claims, Part 4 - Confusing Local with Global Mean Temperatures
On September 6, Matthew Wielicki posted a claim on X that global warming isn't a problem because 2°C warming by 2100 is "about the temperature change from 8am to 10am in most major cities." He then showed a graph of expected temperature changes from 8 am to10 am, from sunrise to afternoon, January to July, etc for various cities.
I think it's fairly easy to show that Wielicki is being dishonest here, since he also flatly contradicts this claim. But before showing him contradicting this claim, let's explain Wielicki's horrible logic. In effect, he's making the simple mistake of confusing local diurnal and seasonal temperature changes with global climate change. When the global mean becomes 2°C warmer, the distribution of temperatures locally and globally also changes, making what used to be extreme heat far more common. In another post, I document that there has been a 220x increase in frequency of extreme summer heat in NH land temperatures with respect to the 1951-1980 mean with less than 1.4°C warming. As we approach 2°C warming, extreme heat becomes much more frequent, ice sheets and mountain glaciers spend more time above freezing, and this results in a shrinking cryosphere and accelerating sea level rise, among other consequences. This affects NYC coastlines, but warming from 8 am to 10 am in NYC does not. Likewise, the LGM almost 20,000 years ago was only about 6°C cooler, and this temperature change is less than the difference between sunrise and afternoon on Wielicki's graph, but both NYC & Boston were covered by 600 m of ice during the LGM. A 6°C change in global mean temperature is very different from a 6°C in daily temperatures globally.
I think it's fairly easy to show that Wielicki is being dishonest here, since he also flatly contradicts this claim. But before showing him contradicting this claim, let's explain Wielicki's horrible logic. In effect, he's making the simple mistake of confusing local diurnal and seasonal temperature changes with global climate change. When the global mean becomes 2°C warmer, the distribution of temperatures locally and globally also changes, making what used to be extreme heat far more common. In another post, I document that there has been a 220x increase in frequency of extreme summer heat in NH land temperatures with respect to the 1951-1980 mean with less than 1.4°C warming. As we approach 2°C warming, extreme heat becomes much more frequent, ice sheets and mountain glaciers spend more time above freezing, and this results in a shrinking cryosphere and accelerating sea level rise, among other consequences. This affects NYC coastlines, but warming from 8 am to 10 am in NYC does not. Likewise, the LGM almost 20,000 years ago was only about 6°C cooler, and this temperature change is less than the difference between sunrise and afternoon on Wielicki's graph, but both NYC & Boston were covered by 600 m of ice during the LGM. A 6°C change in global mean temperature is very different from a 6°C in daily temperatures globally.
And I think Wielicki knows exactly why his logic is wrong. Back in November 2025, he made a post on X that shows exactly why he's wrong now. For Thanksgiving, he informed us that he's "thankful we no longer live in a pre-industrial climate that could freeze the entire River Thames solid for months at a time" - you know, when the globe was ~2°C (or less) cooler than today.
So when GMST was ~2°C cooler, Wielicki admits that this had a significant impact on Great Britain's climate, despite the fact that 2°C is "about the temperature change from 8am to 10am in most major cities." The contradiction here shows that Wielicki can understand why his logic is so terribly wrong.
Wielicki is not alone in making this mistake. Lindzen and Christy wrote a political tract for the CO2 Coalition that made a similar claim. They wrote, "Even if a single station had recorded this [1°C] increase itself, this would take a typical annual range of temperature there, for example, from -10 to 40 degrees in 1900, and replace it with a range today from -9 to 41. People, crops, and weather at that station would find it hard to tell this difference." In my response, I went into a lot more detail in why this logic so horribly bad and misinformed. Lindzen and Christy both know they're being disingenuous here. They understand exactly why they're wrong, and I think Wielicki does as well.
Earlier this year, President Trump appointed Wielicki to head up U.S. Global Change Research Program that is responsible for writing the National Climate Assessments. Congress has mandated that the USGCRP produce a NCA report every 4 years. In April 2025, the Trump Administration dismissed all 400 scientists who were volunteering to compose the NCA6 report, and he terminated the leadership staff of the USGCRP. Previous NCA reports were taken offline (though they are still published online elsewhere). These kinds of posts from Wielicki suggest to me that he will be unable to complete an NCA report (I document more of his incompetence here and here). He simply lacks the competence and integrity to lead the program. If an NCA6 does get published, my guess is that it will be filled with nonsense like this, and if anything it will be another nail in the coffin of contrarian climate thinking. The DOE report was bad enough; an NCA6 under Wielicki's leadership will be much worse.
Wielicki is not alone in making this mistake. Lindzen and Christy wrote a political tract for the CO2 Coalition that made a similar claim. They wrote, "Even if a single station had recorded this [1°C] increase itself, this would take a typical annual range of temperature there, for example, from -10 to 40 degrees in 1900, and replace it with a range today from -9 to 41. People, crops, and weather at that station would find it hard to tell this difference." In my response, I went into a lot more detail in why this logic so horribly bad and misinformed. Lindzen and Christy both know they're being disingenuous here. They understand exactly why they're wrong, and I think Wielicki does as well.
Earlier this year, President Trump appointed Wielicki to head up U.S. Global Change Research Program that is responsible for writing the National Climate Assessments. Congress has mandated that the USGCRP produce a NCA report every 4 years. In April 2025, the Trump Administration dismissed all 400 scientists who were volunteering to compose the NCA6 report, and he terminated the leadership staff of the USGCRP. Previous NCA reports were taken offline (though they are still published online elsewhere). These kinds of posts from Wielicki suggest to me that he will be unable to complete an NCA report (I document more of his incompetence here and here). He simply lacks the competence and integrity to lead the program. If an NCA6 does get published, my guess is that it will be filled with nonsense like this, and if anything it will be another nail in the coffin of contrarian climate thinking. The DOE report was bad enough; an NCA6 under Wielicki's leadership will be much worse.
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