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Examining Dr. John Christy's Global Warming Skepticism

Posted on 12 June 2011 by dana1981

Christy Crocks (200 x 70 pixels)By far the three most prominent and most frequently referenced climate scientists who are "skeptical" of the dangers of human-caused global warming are Dr. Richard Lindzen of MIT, and Drs. Roy Spencer and John Christy of the University of Alabama at Huntsville (UAH).   These are not your typical unqualified "skeptics", like so many others (i.e. computer programmers, politicians, and former political consultants).  No, these are genuine climate scientists who receive government research grants, publish peer-reviewed studies, and have not received any funding from fossil fuel companies in recent years.  Thus their arguments are well worth examining.  Is there scientific validity to their skepticism?

This question is of particular importance since they have recently received so much media attention.  Dr. John Christy, for example, has recently testified before U.S. Congress, appeared on an Australian radio talk show, and on a Canadian radio show.  In these appearances, he advised his audiences that there is a great deal of uncertainty regarding man-made global warming, and that we need not take significant steps to reduce human greenhouse gas emissions.  This advice directly contradicts the findings of the vast majority of Dr. Christy's peers, most recently by the Australian Climate Commission, which concluded that we know beyond a reasonable doubt that humans are the primary cause of the current global warming, and it is critical that we immediately implement policies to reduce global greenhouse gas emissions.

We recently examined the scientific arguments of Dr. Richard Lindzen, and found that his arguments do present a mostly consistent alternative to the man-made global warming theory.  Essentially Dr. Lindzen argues that the climate is not very sensitive to increases in atmospheric greenhouse gases, and the warming we've observed is mainly due to the internal variability of the climate system.  However, we also found that Dr. Lindzen's alternative hypothesis is little more than a flimsy house of cards, with each scientifically faulty argument built upon several other faulty arguments.  In fact every single one of his arguments has turned out to be inconsistent with the observational evidence.  So what about Dr. Christy - does he present a consistent alternative hypothesis to the man-made global warming theory which is more scientifically accurate than Dr. Lindzen's?

No, as it turns out, we find that Dr. Christy's arguments create a similar, but less sophisticated alternative in comparison to Dr. Lindzen's.  The foundation of Dr. Christy's arguments is that despite over four decades of climate science research, we still do not understand the workings of the global climate much better than we did in 1970, and that as a result, we are "jumping to conclusions" in blaming recent global warming on human activities.  However, contrary to Dr. Christy's uncertainty exaggerations, the human influence on the recent global warming is one of the aspects which climate scientists are most certain about.

However, once he sows the seeds of doubt into the minds of his audience, Dr. Christy proceeds to argue, similar to Dr. Lindzen, that recent warming could simply be due to the internal variability of the global climate.  Dr. Christy argues that this is a plausible alternative explanation to man-made global warming because "we", as he puts it, are finding that the climate is not sensitive to greenhouse gases, and he claims that observational data is not consistent with climate model predictions.  Thus, Dr. Christy concludes, reducing greenhouse gas emissions will have little impact on the climate.

As you can see, this is a very similar alternative hypothesis to that put forth by Dr. Lindzen.  In fact, when Dr. Christy says "we" are finding that the climate is insensitive to greenhouse gases, he refers exclusively to studies by Dr. Lindzen and Dr. Spencer.  Virtually all other climate science research has found that the climate is indeed quite sensitive to greenhouse gases, and the work of Dr. Lindzen and Dr. Spencer concluding otherwise contains numerous errors.  And as with Dr. Lindzen's alternative hypothesis, every single one of Dr. Christy's arguments is directly contradicted by the observational data (as illustrated in the links above).

Thus unfortunately we once again find that even the arguments by climate scientist "skeptics" that we need not worry about global warming or greenhouse gas emissions are scientifically unsound.  There's an important distinction to be made here: human-caused global warming is a robust scientific theory which is supported by a vast body of evidence and has withstood extreme scientific scrutiny for many decades.  The alternative hypotheses like that of Dr. Christy, on the other hand, have quickly been falsified by ongoing scientific research.

Additionally, another critical point which Dr. Christy neglects is that even aside from climate change, our carbon emissions are also causing ocean acidification (another major environmental problem which we refer to as "global warming's evil twin"), and there are numerous other issues with our continued reliance on fossil fuels (i.e. peak oil, air pollution, reliance on foreign energy sources, etc.).  It's unfortunate that Dr. Christy and his two "skeptic" colleagues continue to present this misleading and scientifically unsound information to the general public and policymakers, because the more we listen to them and the longer we wait, the worse the consequences will be.

NOTE: As you can see from yet another of John Cook's snazzy buttons at the top of this post, we have launched a comprehensive Christy Crocks page very similar to Monckton Myths and Lindzen Illusions.  We hope people will make use of these resources to respond when these "skeptics" are referenced.  The short URL for the Christy Crocks page is

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Comments 101 to 102 out of 102:

  1. Jonicol

    They are not complete in demonstrating the link between CO2 increases and Global Warming, is the absence, after 25 years of dedicated searching by a large number of internationally distributed groups including in Australia, of any evidence of the "Green House Signature", which was and still is, a very significant result from the atmospheric modeling???

    You are in luck today, I just found a link where they were talking about how they detect the “DNA/fingerprints” (my terms) of CO2 to know, without any doubt, what source said CO2 came from. Something about “various geochemical characteristics” and something about CO2 from different sources having a “different isotopic composition” that are used to determine what/which source the CO2 being geo-chemical-ed/isotopic-ed came from.

    That is how we know that those trying to claim that “natural sources” are the source for the CO2 responsible for global warming have nothing to support their claim.

    To quote one of the experts: There is a way that scientists can tease apart the atmospheric concentration of CO2 to see how much of the CO2 is from natural sources and how much is from combusted fossil fuel sources.

    Here’s how scientists know. The same elements (i.e. same number of protons in the nucleus) with different mass numbers (arising from the different numbers of neutrons in the nucleus) are called isotopes. Each carbon molecule has six protons in the nucleus, but there are many different isotopes with varying numbers of neutrons in the nucleus. Carbon isotopes from different sources are “lighter” (high negative value) or heavier (lower negative value).

    But if you are still trying to peddle the “But they are still not complete in demonstrating that gravity is responsible for keeping us all from naturally floating away into space. I have read on the internet that someone has claimed that angels are responsible by holding us down; prove that is not true?” argument with the assertion that “They are not complete in demonstrating the link between CO2 increases and Global Warming.” You are also in luck.

    Just recently scientists have proven, or are “complete in demonstrating” (if that is how you want to phrase it) what everyone in the literate world has, regardless of what they claim out loud, known all along. That increased CO2 in the atmosphere in the quantities we have spewed are in fact responsible for and currently causing global warming.

    Something about your complete in demonstrating being “found in the spectrum of greenhouse radiation.” That by “Using high-resolution FTIR spectroscopy, we can measure the exact wavelengths of long-wave (infrared) radiation reaching the ground.” Also, something about “we can see that CO2 is adding considerable warming, along with ozone (O3) and methane (CH4). This is called surface radiative forcing, and the measurements are part of the empirical evidence that CO2 is causing the warming.

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  2. Kuni, the person you are replying to hasnt been seen here since 2011.

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