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Showing posts with the label John Christy

John Christy's Misleading Graphs from 2016

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It's been over a decade, but occasionally I still see people sharing the graphs John Christy's presented as testimony in 2016 as "evidence" that models can't accurately predict observations. The graphs have been heavily criticized at RealClimate (see  here  and here ) for very good reasons.  Sometimes these graphs get dressed up with a different aesthetic while keeping the comparison exactly the same. The version below is from a Heritage Foundation "report" published in April of 2026, but the authors didn't even bother to update observations to 2025. They just ignore the last 10 years of observations, possibly because none of the authors had the competency to update the observational data to today. Since Benestad  and Schmidt  have done such a thorough job debunking these types of graphs, I don't see any need to duplicate their efforts, but here's a brief summary of the what's misleading about these graphs: Christy chose comparisons of a...

Satellite Data Tampering by John Shewchuk

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The graph below from John Shewchuk is intended to show that models predict too much warming compared to satellite data. Shewchuk claims that the red line is the average of 102 IPCC CMIP5 model runs for the surface through 50K feet. In all likelihood, this is just lifted from graphs of model-observation comparisons that John Christy has plotted in the past. Shewchuk claims the blue line is UAH satellite observations for the total troposphere layer (TTT). The problems with this graph are numerous, and many of the problems are inherited from Christy's graph (problems with his comparison are well-documented ). The two time series are separated from each other even in 1980 to exaggerate the differences between the two (even if the trendlines do intersect at 1980). The 102 model runs are not shown, only the model mean, and the 95% confidence interval is also not shown, so we have no idea what the spread in the model runs might be. But Shewchuk has added his own dishonest twist to this g...

Review of Spencer's New Paper on Urban Heat Islands

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A new paper[1] by Spencer and Christy was published on urban heat islands (UHI), and I'd like to clarify what it says and what can actually be claimed as a result of it. The reason why has to do with a recent blog post from WUWT that claims the paper shows that 65% of global warming is due to UHI warming effects, rather than increasing greenhouse gas concentrations. Chris Rotter at WUWT says, A new study from the University of Alabama in Huntsville addresses the question of how much the Urban Heat Island (UHI) effect is responsible for the higher temperatures at weather stations across the world. Dr. Roy Spencer and Dr. John Christy have spent several years developing a novel method that quantifies, for the first time, the average UHI warming effects related to population density. Their finding: no less than 65% of “runaway global warming” is not caused by our emissions of carbon dioxide, but by the urbanization of the world. There's very little in this that resembles what the...

Responding to the CO2 Coalition's "Fact #21" on Climate Models

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CO2 Coalition 's " Fact #21 " claims that "IPCC models have overstated warming by up to three time too much." According to this claim to fact, John Christy's testimony on "February 2016 to the U.S. House Committee on Science, Space & Technology included remarkable charts that document just how much the models overestimate temperatures. The red line in the chart shows the average of 102 climate model runs completed by Christy and his team at the University of Alabama at Huntsville using the models on which the IPCC itself relies. Also shown on the chart are the actual, observed temperatures. The models exaggerate warming, on average, two and a half times the actual temperature (or three times over in the climate-crucial tropics). Here's the graph they use to support this claim. The above graph reports to show 32 models and 102 model runs within the CMIP5 model ensemble. They are limited to those runs in the KNMI Climate Explorer. The models are s...

Is Global Mean Surface Temperature Misleading?

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In December 2020, the CO2 Coalition published a document authored by Richard Lindzen and John Christy entitled, The Global Mean Temperature Anomaly Record: How it works and why it is misleading . It should be acknowledged that this document is a political and partisan document. It is not written to advance our understanding of the GMST anomaly record. It's written to affect policy. Caleb Stewart Rossiter, Executive Director of CO2 Coalition, makes this nearly explicit. After asserting that academic publishing has been taken over by a "'climate crisis' and an 'easy to change sources' narrative, he says, "this paper, which in earlier days would have, as a matter of course, been published by a scholarly journal, now finds a home with our advocacy group." This is not an academic paper (and this by itself is not a criticism of the paper), and it would never be published in a scholarly journal, since the intended audience is general voters, not scholars. It...