John Christy is a climate scientist, with a particular focus in atmospheric temperature trends. Some sources present Christy as being an intellectually serious "skeptic" of carbon-dioxide-induced (CO2-induced), man-made climate change [7; 26 - 31]. Yet Christy has repeatedly misled Congress and the public. Christy's most egregiously misleading statements include:
- Christy insinuates that the United States National Oceanic and Atmospheric Administration (NOAA) ocean temperature data was manipulated, even though other data sources confirmed the NOAA's results. Christy provides no evidence for his charge of data manipulation. Instead Christy makes the charge simply because the NOAA data conflicts with Christy's claim that ocean warming is due to natural, non-man-made factors. Christy later co-authored research that agreed with the NOAA results he previous criticized (for more on this, see "Myth: Karl et al. of the NOAA Misleadingly Altered Ocean Temperature Records to Increase Global Warming" and section 3.8 of part 2 of my series on "John Christy and the Tropical Tropospheric Hot Spot").
- Christy falsely argues [21; 22] that climate scientists and a scientific journal were involved in a conspiracy against him.
- Christy presents temperatures from one layer of the atmosphere (the troposphere) as if they were temperatures from a different, higher layer of the atmosphere (the stratosphere). This allowed Christy to avoid addressing stratospheric cooling. Stratospheric cooling is one of the hallmarks of CO2-induced global warming; solar-induced global warming would not cause this cooling, as stated in a source that Christy himself co-authored. Stratospheric cooling is therefore inconvenient for Christy's position, since Christy hopes to attribute much of the recent global warming to the Sun, not CO2. This may explain why Christy obscures the presence of stratospheric cooling, even though Christy knows that the stratosphere cooled. So Christy takes tropospheric warming and misrepresents it as being stratospheric warming, when he knows the stratosphere actually cooled (for more on this, see sections 2.1 and 2.2 of "Myth: The Sun Caused Recent Global Warming and the Tropical Stratosphere Warmed").
- When Christy claims that the stratosphere warmed, Christy contradicts his co-authored research and his political testimony. And when Christy conflates the stratosphere with the troposphere, Christy blatantly contradicts his previous statements he cited to Congress (for more on this, see section 2.2 of "Myth: The Sun Caused Recent Global Warming and the Tropical Stratosphere Warmed").
- For years Christy erroneously claimed that the troposphere had not warmed. Even after admitting the troposphere warmed, Christy continued to use a number of tactics to under-estimate tropospheric warming, including using a temperature adjustment that falsely assumed that the lower troposphere cooled at noon when the Sun was shining and warmed at midnight (for more on this, see section 2.3 of "Myth: Santer et al. Show that Climate Models are Very Flawed").
- Christy cherry-picks in order to falsely claim that the satellites showed no global warming over a recent 18 year period (for more on this, see section 3.4 of "John Christy, Climate Models, and Long-term Tropospheric Warming" and "Myth: No Global Warming for Two Decades").
- Christy noted that another satellite-based research team, RSS, under-estimated global warming in version 3 of RSS' analysis. He also stopped citing a particular weather-balloon-based analysis that under-estimated warming. Christy then modified his own UAH satellite-based analysis so that it showed less warming than the weather-balloon-based analysis and showed less warming than RSS' version 3 analysis. So Christy knowingly modified his UAH analysis to show less warming than analyses he knew under-estimated warming. His modified UAH trend shows as much as, or less warming than, a re-analysis known as ERA-I, even though the ERA-I team and other researchers admit that ERA-I under-estimates warming (for more on this, see sections 2.1 and 2.2 of "Myth: Evidence Supports Curry's Claims Regarding Satellite-based Analyses and the Hot Spot").
- For over two decades Christy falsely assumed that differences between observational analyses and model-based projections were due to errors in the models, despite the fact that he admitted he could not fully discount other explanations for these differences. He made this admission to informed scientists in his peer-reviewed worked, but said otherwise when writing in non-peer-reviewed politically-motivated "reports" for the general public. Scientists then showed that these alternative explanations were better supported than Christy's "models over-estimate CO2-induced warming" explanation. Christy jumped to model error as an explanation despite the fact that a better explanation was often an error in his own analysis, as, for example, in the case where he falsely claimed the troposphere had not warmed. In a 2007 paper, he even went so far as to use a statistical test that yielded absurd results, even on randomized artificial data, just in order to claim a statistically significant difference between model-based projections vs. observational analyses (for more on this, see sections 2.2, 2.3, and 2.4 of "Myth: Santer et al. Show that Climate Models are Very Flawed").
- Christy misrepresented 1988 model-based projections from the climate scientist James Hansen, and further cast doubt on atmospheric warming. Yet atmospheric warming occurred, as Hansen predicted, despite Christy falsely claiming there was no atmospheric warming and claiming that future warming was as likely as future cooling (for more on this, see section 2.4 of "Myth: Santer et al. Show that Climate Models are Very Flawed").
- Christy claims that climate models over-estimate CO2-induced warming. Yet he conveniently ignores evidence that the climate models likely under-estimate long-term CO2-induced warming and evidence that various factors amplify CO2-induced warming. He also willfully conceals that fact that, by his own reasoning on tropospheric warming trends, climate models under-estimate how sensitive temperature trends are to CO2 increases (for more on this, see sections 3.3 and 3.4 of "John Christy Fails to Show that Climate Models Exaggerate CO2-induced Warming", section 2.5 of "Myth: Attributing Warming to CO2 Involves the Fallaciously Inferring Causation from a Mere Correlation", and section 2.4 of "Myth: Santer et al. Show that Climate Models are Very Flawed").
- In a non-peer-reviewed blog article Christy cited to Congress, Christy claims that a solar-induced ocean cycle (ENSO) caused most of the recent tropospheric warming. He also states that CO2 caused no significant, observable tropospheric warming and no significant atmospheric temperature trends. He makes these claims in order to undermine government regulation of CO2 emissions. But in a subsequent peer-reviewed paper, Christy admits that ENSO did not cause most of the recent tropospheric warming and that CO2 caused statistically significant, observable tropospheric warming. He also admits that CO2 caused stratospheric cooling (for more on this, see sections 2.1, 2.3, and 2.5 of "Myth: The Sun Caused Recent Global Warming and the Tropical Stratosphere Warmed").
- Christy uses a solar index to argue to Congress that solar-induced changes in ENSO, not increased CO2, caused most of the recent global warming. He later admitted that this arbitrary index compromised the relationship between the solar index and the temperature trends the solar index was meant to predict (for more on this, see section 2.3 of "Myth: The Sun Caused Recent Global Warming and the Tropical Stratosphere Warmed").
- In 2007, Christy admitted to the government that human burning of fossil fuels caused most of the increase in atmospheric CO2 levels. He also admitted that increased greenhouse gases caused most of the global warming over the past 50 years. Ten years later in 2017, Christy no longer accepted that increased greenhouse gas levels caused most of the recent global warming, despite the fact that even more evidence of CO2-induced warming accumulated in the ten years from 2007 to 2017 (for more on this, see section 2.5 of "Myth: The Sun Caused Recent Global Warming and the Tropical Stratosphere Warmed").
- Christy argues against the efficacy of policies that reduce human emissions of greenhouse gases. Yet Christy admits that an international agreement known as the Montreal Protocol helped reduce human emission of ozone-depleting gases, leading to a stabilization of ozone levels and mitigation of the contribution of ozone-depletion to lower stratospheric cooling (for more on this, see sections 2.1 and 2.5 of "Myth: The Sun Caused Recent Global Warming and the Tropical Stratosphere Warmed").
- Christy insinuates to Congress and the general public that amplified warming in the tropical lower atmosphere (the tropical troposphere) is specifically a signature of CO2-induced global warming, even though Christy likely knows that this amplification should occur with any cause of strong tropical warming at the Earth's surface. This means that even if non-man-made factors caused most of the recent global warming as Christy claims, then this tropospheric amplification should still occur (for more on this, see "Myth: The Tropospheric Hot Spot is a Fingerprint of CO2-induced Warming").
- In his Congressional testimony, Christy presents a graph that shows evidence of amplified warming in the tropical troposphere. Christy then brazenly contradicts this graph by citing a report/blogpost in which he claims that there is no evidence of this tropospheric amplification. Then Christy provides a graph of this amplification to someone else for their Congressional testimony (for more on this, see "Myth: John Christy Thinks There is No Evidence of the Hot Spot").
- Christy, when addressing Congress, fails to discuss numerous studies that show amplified warming in the tropical troposphere, even though this evidence contradicts Christy's claims. Christy then blatantly moves the goalposts when it appears that warming trends may pass some of his criteria for tropical tropospheric amplification (for more on this, see "Myth: John Christy Thinks There is No Evidence of the Hot Spot", along with section 2.4 of "Myth: The Tropospheric Hot Spot does not Exist").
The climate scientist Ben Santer allegedly said that Christy was "not even a third-rate scientist ," and that Christy had "made a scientific career out of being wrong ." I respectfully disagree. Christy seems fairly skilled when it comes to scientific research. But Christy made his public name by being misleading and by telling political conservatives what they wanted to hear. Christy makes claims in public that likely would never make it past competent peer review. Understanding this point helped me better grasp the public debate and scientific discussion on climatology.
When I first became interested in climate science and man-made (anthropogenic) climate change, I thought that much of the discussion was made up of "skeptics" and "consensus scientists." I believed that Christy was a member of the former group, as were Roy Spencer, Richard Lindzen, Judith Curry, and other prominent critics of mainstream climate science. These skeptics, I thought, did not accept the some of the mainstream science on anthropogenic climate change, but sufficient evidence would probably convince these folks. These skeptics were likely wrong, but they were rational, as intellectually honest as at least your average person, and not denialists. They might present evidence that would change my mind.
I was wrong. As I read more scientific research, examined the claims made by these "skeptics" on their blogs and other non-peer-reviewed outlets, etc., I realized that I had mis-characterized the discussion. The discussion that I and other non-experts were viewing was largely not a debate between "skeptics" and "consensus scientists." It was more like the debates on AIDS denialism and the anti-vaccination movement, fields closer to my area of expertise.
Since at least the early 2000s, the real scientific skeptics accepted that no sound evidence had been provided showing that vaccines caused autism. What's left now are anti-vaxxers who still think that vaccines cause autism, despite overwhelming evidence to the contrary. And since at least the early 1990s, the real scientific skeptics accepted that HIV causes AIDS. What's left now are AIDS denialists who do not accept that HIV causes AIDS, in spite of the overwhelming evidence on this topic.
Similarly, the real skeptics (such as Richard Muller [1; 20], Ronald Bailey , Jerry Taylor [24, from 6:35 to 34:59], and Greg Fishel ) already changed their mind in response to the overwhelming evidence that humans caused most of the post-1950s global warming. What's left now are people like Christy, who keep their position in spite of, not because of, the evidence. So the climate science debate I was observing was a debate between ideologically-motivated denialists vs. a well-supported, evidence-based scientific consensus [2 - 6; 8 - 10; 12 - 19; 23]:
"Denialism can be recognised by the presence of six key features [...]. [...] It is, however, important not to confuse denialism with genuine scepticism, which is essential for scientific progress. Sceptics are willing to change their minds when confronted with new evidence; deniers are not ."
"Arguing with science denialists is usually a waste of time. They masquerade as ordinary colleagues who adhere to the overarching goal of science, i.e. to find the best approximations of truth in the matter under consideration. The crucial difference is that your colleagues will accept a scientific statement if provided with sufficiently strong reasons to do so. In contrast, climate science denialists, like other pseudoscientists, tend to be driven by motives that make them impossible to convince, however strong the arguments they are presented with [emphasis added] [23, section 5]."
I compare this denialism to other examples of science denialism in "Myth: Attributing Warming to CO2 Involves the Fallaciously Inferring Causation from a Mere Correlation". You may disagree with my assessment. I just ask that you scrutinize Christy's claims (and the claims of other prominent faux "skeptics", such as Roy Spencer, Richard Lindzen, Willie Soon, Judith Curry, Anthony Watts, David Evans, Tim Ball, William Happer, Craig Loehle, Patrick Moore, Patrick Michaels, and Piers Corbyn) in light of scientific evidence and sound reasoning. I think you will find their positions are not just wrong, but obviously misleading. My blogposts cite evidence in support of this point, at least with respect to Christy's claims, among others; for example, I summarize some of Judith Curry's deeply flawed claims in "Myth: Judith Curry Fully and Accurately Represents Scientific Research". So if you do not believe me, then feel free to examine the sources I cite in my posts and come to your own conclusion.
- "Richard Muller: I was wrong on climate change"
- "Science denialism: Evolution and climate change"
- "How the growth of denialism undermines public health"
- "Denialism: what is it and how should scientists respond?"
- "The ethics of belief, cognition, and climate change pseudoskepticism: Implications for public discourse"
- "Manufactured scientific controversy: Science, rhetoric, and public debate"
- "Though scorned by colleagues, a climate-change skeptic is unbowed"
- "Climate Denial 101: A User’s Guide to the arguments of global warming skeptics"
- "Sceptics and deniers of climate change not to be confused"
- "What evidence would persuade you that man-made climate change is real?"
- "Promoting pro-environmental action in climate change deniers"
- "Debating global warming in media discussion forums: Strategies enacted by “persistent deniers” and implications for schooling"
- "Countering evidence denial and the promotion of pseudoscience in autism spectrum disorder"
- "Science denial as a form of pseudoscience"
- "Science denial: a guide for scientists"
- "Science denial and the science classroom"
- "AIDS denialism and public health practice"
- "The conversion of a climate-change skeptic"
- "Open letter to the climate science community: Response to "A Climatology Conspiracy?""
- "Dealing with climate science denialism: experiences from confrontations with other forms of pseudoscience"
- "A paid climate change skeptic switches sides"
- "How a North Carolina meteorologist abandoned his climate change skepticism"