Should you believe anything John Christy says?

This Skeptical Science repost debunks John Christy’s recent House testimony.

On March 8, 2011, the U.S. House Energy and Commerce Subcommittee on Energy and Power held a hearing entitled entitled “Climate Science and EPA’s Greenhouse Gas Regulations.”  As the US Environmental Protection Agency (EPA) has begun regulating greenhouse gas emissions from large sources, Congressional Republicans are seeking justification to revoke their authority to do so through the Energy Tax Prevention Act (H.R. 910).  This hearing was held to allow scientists from both “sides” to present their case as to whether our understanding of climate science justifies the EPA’s greenhouse gas regulations.

One of the top witnesses called by the Republicans was Dr. John Christy.  His full written testimony can be viewed here.   Most of the quotes below come directly from that written testimony.  As we’ll see below, Christy’s case for continuing on our current path and revoking the EPA’s greenhouse gas regulation authority is primarily based on a repetition of a number of long-debunked myths.

Extreme Weather

Christy began his written testimony by discussing various recent extreme weather events, and arguing that they cannot be attributed to human greenhouse gas emissions.

As Francis Zwiers noted in his testimony for this hearing, while individual extreme weather events cannot be blamed on global warming, “two new papers in Nature (Min et al. 2011, Pall et al. 2011) have presented evidence that changes in the intensity of extreme precipitation since the middle of the 20th century may be linked to human induced global warming, and that in at least one instance, that human influence on climate had likely substantially increased the risk of flooding.”  Other recent research has detected a human influence in observations of extreme temperatures (e.g., Christidis et al., 2005, 2010; Zwiers et al., 2011).

Temperature Trend

In 1994, Nature magazine published a study of mine in which we estimated the underlying rate at which the world was warming by removing the impacts of volcanoes and El Ni±os (Christy and McNider 1994.)…The result of that study indicated the underlying trend for 1979-1993 was +0.09°C/decade…I have repeated that study for this testimony with data which now cover 32 years…In an interesting result, the new underlying trend remains a modest +0.09 C/decade for the global tropospheric temperature.

Christy’s method of filtering out the El Ni±o influence – by removing the tropical sea surface temperature (SST) trend – seems like a rather blunt and imprecise way to remove the El Ni±o Southern Oscillation (ENSO) signal.  After all, the tropical sea surface temperatures could have an upward trend for other reasons (for example, due to an increased greenhouse effect!).  Christy’s assumption that the tropical SST trend could only be due to ENSO seems unjustified.

In 2008, David Thompson attempted to extract the ENSO signal from the HadCRUT3v data using a different methodology, and Gavin Schmidt applied the same approach to the GISTEMP data.  They found that removing the ENSO signal from the surface temperature data did not change the global warming trend over the past 30 years.

Similarly, Tamino recently removed the estimated impact of El Ni±o, volcanic eruptions, solar variation, and the residual annual cycle from various global temperature data sets (Figure 1).

tamino trend ENSO volcanic removed

Figure 1: Adjusted annual average temperature data with the estimated impact of El Ni±o, volcanic eruptions, solar variation, and the residual annual cycle removed (Source: Open Mind)

The resulting average warming trend is approximately 0.17°C per decade; embarrassingly enough, even Christy’s own UAH data show 0.16°C per decade, far larger than 0.09°C per decade trend of his testimony.

Moreover, as the name suggests, ENSO is an oscillation.  It alternates between positive and negative states, and thus does not cause long-term warming trends.  ENSO also does not create or retain heat; it just moves heat from oceans to air and vice-versa.  Thus, even if it caused a surface air warming trend (like 35% of the warming over the past 32 years, as Christy argues), the oceans would cool correspondingly, which they are not.  Thus it appears that Christy’s reduced warming trend is a result of his imprecise method of attempting to remove the ENSO influence.

Should Have Seen More Warming?

+0.09 C/decade for the global tropospheric temperature…is still only one third of the average rate the climate models project for the current era (+0.26°C/decade.)

As we’ve previously examined, the Earth’s surface temperature is warming almost exactly as much as climate models expect.   However, it’s true that climate models also expect the lower troposphere to warm slightly faster than the surface, and that according to UAH, it is not.  That being said, the discrepancy may very well be due to difficulties in analyzing the raw satellite data, which is fraught with problems like orbital decay of the satellites, and the challenge in isolating each different layer of the atmosphere.

UAH does not have the only approach to analyzing the satellite data.  For example, Fu et al. (2004) apply a slightly different correction to attempt to isolate the lower troposphere temperatures, and conclude:

The resulting trend of reconstructed tropospheric temperatures from satellite data is physically consistent with the observed surface temperature trend. For the tropics, the tropospheric warming is ~1.6 times the surface warming, as expected for a moist adiabatic lapse rate.

Vinnikov & Grody (2006) have suggested that the method used by the UAH group was insufficient to compensate for the impact of the diurnal cycle on the observations.  Like Fu et al., their work concludes that the troposphere is warming faster than the surface, as climate models expect.

The observations at the surface and in the troposphere are consistent with climate model simulations…The resulting global averaged tropospheric trend is +0.20 K/10 yr.

In fact, as tamino noted,

All the [satellite lower troposphere temperature] analyses except UAH are compatible with computer model projections of tropospheric warming; the error ranges include the values expected from model simulations.

Perhaps Christy should consider the possibility that the problem is not that the troposphere isn’t warming as much as climate models expect, but rather that his analysis is (still) underestimating the troposphere warming rate.  After all, UAH does not have a stellar track record when it comes to accurate data analysis.

Heating from Land Use Changes

Warming is dominated by increases in nighttime temperatures, with little change in daytime temperatures. This pattern of warming is a classic signature of surface development (land cover and land use change) by human activities.

Actually, greater warming during the night than day is a key signature of an increased greenhouse effect.

Christy’s argument here is not very different from blaming instrumental global warming measurements on the urban heat island (UHI) effect.  However, scientific organizations make great efforts to remove these types of local influences, and according to Menne (2010), are very successful in doing so.  That’s why rural stations show the same warming trend as urban stations, well-sited temperature stations the same as poorly-sited stations, and satellites the same as surface stations.  The evidence is clear, and the warming trend is very real.

Hot Spot

One of the clearest signatures or fingerprints of greenhouse gas warming as depicted in climate models…consists of a region of the tropical upper atmosphere which in models is shown to warm at least twice as fast as the surface rate of warming…We, and others, have tested this specific signature, i.e. this hypothesis, against several observational datasets and conclude that this pervasive result from climate models has not been detected in the real atmosphere.

As we have previously discussed several times, and as Christy should very well know, the tropical troposphere hot spot is not an anthropogenic signature.  Rather, it is the expected result of any global surface warming, and indeed there is evidence that the hot spot exists.

If Christy wants to argue that the hot spot is an anthropogenic fingerprint, he’ll have to explain why the adiabatic lapse rate only applies to warming caused by greenhouse gases, and why climate models predict a hot spot from warming caused by solar and other natural forcings as well.  Frankly it’s very disappointing that any climate scientist would argue that the ‘hot spot’ is an anthropogenic signal.

Climate Sensitivity

Spencer tracks large global temperature changes over periods of several weeks…he finds the real climate system is dominated by negative feedbacks (probably related to cloud variations) that work against changes in temperature once that temperature change has occurred.

We cannot evaluate the equlibrium climate sensitivity to a large energy change over periods of decades to centuries by looking at global temperature changes over periods as short as weeks.  This approach is fundamentally flawed, and Spencer’s results go against the many different lines of evidence using both empirical observational data and climate models which are consistent with the IPCC’s range of climate sensitivity values.

Additionally, several recent studies have examined the cloud feedback which Spencer argues is negative, but based on observations over much longer timeframes both in the tropical Pacific region (Lauer et al. 2010, Clement et al. 2009) and globally (Dessler 2010).  These studies all conclude that the cloud feedback is likely positive.

If Christy wants us to believe the many lines of evidence supporting the IPCC’s climate sensitivity range are wrong, he’ll have to do better than looking at temperature changes over inappropriately brief timeframes while ignoring the many other studies using larger amounts of data which contradict Spencer’s results.


The IPCC and other similar Assessments do not represent for me a consensus of much more than the consensus of those who already agree with a particular consensus.

The scientific consensus on man-made global warming is very well documented, and 113 countries signed onto the IPCC report.  Christy needs to just accept that very few climate scientists agree with his position.

Impact of Carbon Regulations

We calculate that the impact of legislative actions being considered on the global temperature is essentially imperceptible….downward adjustments to North American coal use will have virtually no effect on global CO2 emissions.

Christy is essentially promoting the Tragedy of the Commons here.  If just the USA reduces its carbon emissions, it won’t significantly reduce global emissions.  And if every country makes the same argument, nobody reduces emissions.  This is the purpose of international conferences and treaties – to get all nations to agree on reducing emissions.  And as the largest historical carbon emitter, the USA is a lynchpin in international negotiations.

More Carbon is Better?

…the many positive benefits of higher concentrations of CO2 in the atmosphere, especially for the biological world.

As I recently discussed, we are currently on a path to trigger the Earth’s sixth mass extinction event, with climate change playing a significant role.  The current rate of species extinctions far exceeds the natural background rate.  And as shown by the Penn State interactive application, production of many key agricultural crops will decline in a warming world, particularly at low latitudes.  Positive benefits of higher CO2 concentrations for the biological world?  Hardly.

Christy’s Case

In attempting to argue that climate change is not dangerous and EPA regulation of carbon emissions is unnecessary, Christy has mainly relied on repeating several long-debunked myths:

Christy also tried to argue that we can’t blame recent extreme weather on climate change, even though there is evidence for a human signature in recent extreme weather increased frequency, and what we’re concerned about is future climate change.  He tried to attribute a significant amount of the recent warming to ENSO, even though ENSO physically cannot cause a long-term global warming trend, and thus incorrectly claimed we should have seen more warming.  And he tried to argue that climate sensitivity is low, based on data over a timeframe of just weeks.

Christy’s disappointing testimony is a litany of already disproven assertions.  “Skeptics” will have to do much better to justify continuing on our current extremely high risk business-as-usual climate path.  The EPA’s mandate to regulate greenhouse gas emissions is based on the conclusion that those emissions pose a threat to public health.  Christy’s testimony only served to facilitate the Congressional Republicans’ ideologically driven efforts to revoke the EPA’s authority to contribute towards the protection of our future.  By his testimony, Christy did no service to his country.

— dana1981, Skeptical Science.

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13 Responses to Should you believe anything John Christy says?

  1. Richard Brenne says:


  2. Dana says:

    Thanks for the re-post, Joe.

    Before his testimony on Tuesday, I wouldn’t have necessarily said no. At least Christy doesn’t write misleading media articles like Lindzen, or write a conspiratorial blog like Spencer, or sign onto every “skeptic” letter or list (like both Lindzen and Spencer). But wow, his testimony was just appalling.

  3. MapleLeaf says:

    “Should you believe anything John Christy says?”

    An emphatic no!

    And one can add the following to people who are not to be trusted on the AGW file (it is a long one and the one below is not complete, feel free to add names):

    de Freitas
    Pielke Snr and Snr (I’m still on the fence though)

    All of the above have been exposed for engaging in one or more of the following;

    1) Data fudging and/or scientific misconduct
    2) Misrepresenting and/or distorting climate science and scientific findings
    3) Making false statements about climate science and scientists
    4) Conducting flawed and sub-par science
    5) Accepting money from the FF industry to misinform and contribute to a campaign of disinformation
    6) Attacking honorable and reputable climate scientists, while doing the very things that they are falsely accusing the climate scientists of doing
    7) Harassing and libeling climate scientists
    8) Perverting and subverting the peer-review process
    9) Plagiarism
    10) Being lap dogs for conservative ideologues and politicians

    Any takers on allocating numbers to the names?

  4. Mark S says:

    Following up on the list from mapleleaf, here is a great link that everyone should have. It’s a fairly comprehensive list of those in the denier camp. It give a brief synopsis of listed individuals activities on climate change.

  5. lizardo says:

    Was Christy’s main reason for being invited to sound like a scientist and talk over the heads of committee members and press? and then say, no consensus, what about China, GW could be better, the usual… which is the takeaway they want.

  6. Richard Brenne says:

    Mapleleaf (#3) – That’s a good list, and you have some names that Desmogblog should have on their longer list (with bios), notably Judith Curry and Pielkes Sr. and Jr. who are not always deniers, exactly, but often delayers or confusers or Confusionists, as Joe says.

    Both lists should include William Gray, Professor Emeritus (of hurricane forecasting, which Kerry Emanuel told me is a “Dark art”) from Colorado State, and George Taylor, a good meteorologist who is hopeless about climate change and was thus let go by Oregon State.

    Then both lists should be synthesized with Rolling Stone’s lists of those most damaging the climate, and a list I believe Mike Roddy compiled and posted on-line, I think with The Beast. Then they should be listed in numerical order (constantly updated) according to the harm they’ve done, are doing, and have vowed to continue to do.

    The list should include first names, titles, affiliations and bios, including age. Not that age should be a disqualifying factor in and of itself, but Fred Seitz was sowing the seeds of all of our destruction at age 96, and then made a quick and quite complete getaway that is fairly common for people around that age.

    Freeman Dyson is approaching 90, William Gray is also well into his 80s and appears to have grown far more cantankerous after a personal loss, some are devout fundamentalists and evangelicals and the reader has the right to try to determine which of these things might be a factor, including of course any financial benefit from any fossil fuel companies (we all benefit indirectly from the fossil fuels that power around 80 per cent of our economy), however circuitous or laundered the money has become by consevative non-think tanks.

    This list should be as accurate and updated as possible, with links to their Wikipedia and other bios, but most of all with strong opinions about their impacts.

    Then they should be opposed in every legal and peaceful way possible.

    Just as Shakespeare and other playwrights have published lists of characters with bios, our Shakespeare of climate, Joe, might consider the same that can be linked to from Climate Progress main page, because the same names like these come up again and again, and old and new visitors to CP would appreciate having that reference in a continuous and easily accessible place.

    Then a list of the climate hawk heroes should also be compiled, and if Joe’s too modest I’ll write his bio and put it at the top, together with Hansen’s, McKibben’s and Gore’s.

  7. Dana says:

    lizardo – Christy and Pielke Sr. were invited so that the Republicans could claim that there are “skeptic” scientists and thus the EPA’s authority to regulate greenhouse gas emissions is questionable/unjustified/whatever. The EPA can only regulate greenhouse gases if they endanger public health, so to revoke that authority, Republicans have to make the case that they don’t.

    Basically even though they’re anti-science, the Republicans don’t want to seem anti-science, so they called in Christy and Pielke Sr. to give them some sort of credibility.

  8. MapleLeaf says:


    This was just posted at Michael Tobis’ site with Dr. Santer’s permission. These are very disturbing revelations and I would hope that Christy’s misconduct doesn’t go unchallenged:

    “Via a mailing list, reproduced here with permission:

    I have had a quick look at John Christy’s recent Congressional testimony. Many aspects of it are deeply troubling. From my own personal perspective, one of the most troubling aspects is that Christy cites a paper by David Douglass, John Christy, Benjamin Pearson, and S. Fred Singer. The Douglass et al. paper appeared in the online edition of the International Journal of Climatology (a publication of the Royal Meteorological Society) in December 2007.

    Shortly after its publication, it became apparent that the authors of the Douglass et al. paper had applied a flawed statistical significance test. Application of this flawed test led them to reach incorrect scientific conclusions.

    Together with a number of colleagues (including Gavin), I prepared a response to the Douglass et al. paper. Our response was published by the International Journal of Climatology in October 2008. (DOI: 10.1002/joc.1756) I am also appending a “fact sheet” providing some of the scientific context for both the Douglass et al. and Santer et al. International Journal of Climatology papers.)

    To my knowledge, the Douglass et al. International Journal of Climatology paper has never been retracted. Nor have the authors acknowledged the existence of any statistical errors in their work. The fact that John Christy has now cited a demonstrably-flawed scientific paper in his Congressional testimony – without any mention of errors in the Douglass et al. paper – is deeply disturbing.

    It is my opinion – and the opinion of many of my scientific colleagues – that the Douglass et al. International Journal of Climatology paper represents an egregious misuse of statistics. It is of great concern that this statistically-flawed paper has been used (and is still being used) as crucial “evidence of absence” of human effects on climate.

    Benjamin D. Santer
    Program for Climate Model Diagnosis and Intercomparison
    Lawrence Livermore National Laboratory”

  9. MapleLeaf says:

    Oh this is funny! :) Good on ya Senator Markey:

  10. GasMan says:

    Mapleleaf, please tell Dr. Santer, the Honorable Senator Inhofe only appreciates discredited and egregious climate studies.
    My real question(showing my ignorance here) is why would Christy or anyone want to remove El Nino from calculations of warming? Is that not part of the accumulated heat in the ocean? Aren’t those the warmest years? This does not make sense to me. Is this just his attempt to minimize the amount of warming?

  11. Susan Anderson says:


  12. Dana says:

    GasMan – El Nino is part of a natural cycle (we don’t know exactly what causes it), so it’s a valid approach to try and remove its signal from the temperature data to try and hash out the anthropogenic trend. The problem is that Christy didn’t approach it correctly, and those who do it right find that removing ENSO doesn’t impact the long-term warming trend, as it shouldn’t.

  13. Looking for something else I found the following clip again where at 1:57 Christy replies, to Gavin Schmidt:

    John Christy VS Gavin Schmidt On Climate Gate

    ‘…What is being referred to here is being assumed from climate models…’

    So, in response to the question posed in the title of this article the answer has to be a resounding NO!

    Christy should get hold of a copy of the recently published ‘The Warming Papers’ and read up on climate research and the use of climate models where he will learn that climate models are only one plank that supports the body of knowledge. Is he not smarter than this?