The Intersection

My Debate Comments

Well, the event yesterday at the Skeptics Society conference here in Pasadena went very well, I think. I’m not going to speculate on who “won” the debate between Ron Bailey and myself, but certainly a lot of people came up to me afterwards and thanked me for what I had to say.

I won’t give you the full rundown here, but I will provide a written out version of roughly what I had to say in my opening remarks at the debate–comments directly inspired by the “controversy” on this blog over this conference and who the keynote speakers are (Michael Crichton and John Stossel). Here are my comments (to a rough approximation; I speak improvisationally from notes so these are not the exact words):

Before I lay out my argument, I hope you will indulge me in a brief editorial comment. This is something I owe this to the readers of my blog, some of whom questioned whether I ought to speak at this event at all, given who the keynote speakers are and the likely global warming “skepticism” that they will espouse. But the point I want to make is very germane to the subject at hand as well.

I’m someone who has a long history of being a “skeptic” (at least insofar as someone who’s 28 years old can have a “long history” of anything). And I have always defined skepticism according to Carl Sagan’s famous mantra: “extraordinary claims require extraordinary evidence,” a position that I whole-heartedly embrace. However, in light of Sagan’s standard, I have been very disturbed to see the rhetoric of skepticism misapplied or misused to attack either non-extraordinary claims, or those that are in fact well-supported by strong or even extraordinary evidence.

The theory of anthropogenic global warming today is supported by very powerful evidence–interlocking data and theory across a variety of fields. You might call the level of evidentiary support for it “extraordinary.” But perhaps even more importantly, the notion that humans might contribute to global warming should not be considered an “extraordinary claim” at all today in the sense meant by Carl Sagan. In fact, given what we know about some basic principles in physics, the concept of anthropogenic global warming ought to be very easy to accept and understand.

Skeptics have a long history of going to the mat to defend Charles Darwin, whose central work, The Origin of Species, came out in 1859. What’s probably much less know to this crowd, however, is that in the same year, the Irish scientist John Tyndall gave the first more or less accurate description of the greenhouse effect. As Tyndall put it:

The solar heat possesses…the power of crossing an atmosphere; but, when the heat is absorbed by the planet, it is so changed in quality that the rays emanating from the planet cannot get with the same freedom back into space. Thus the atmosphere admits of the entrance of the solar heat, but checks its exit; and the result is a tendency to accumulate heat at the surface of the planet.

Tyndall also experimented with the radiative properties of atmospheric gases like carbon dioxide and water vapor, and found that these gases are opaque to infrared radiation emanating from the earth. There is no real scientific debate about any of this today; and from Tyndall’s insights, all else follows when it comes to human-caused global warming.

So the scientific foundation here was very well established a very long time ago. This is not, accordingly, an area where the principles of Sagan need to be applied–and indeed, “skeptics” who do so may well be abusing the rhetoric of skepticism itself.

All of that said, I am very glad that I came to this conference. The morning sessions were very serious intellectually and the scientists and others presenting did a very good job of explaining basic climate science and why we have a problem on our hands. I was very impressed with the whole show, and I want to thank Michael Shermer for inviting me to be part of it, and Ronald Bailey for a good debate.

P.S.: Off to Flagstaff now for some Henry David Thoreau type seclusion and writing; I won’t be blogging or answering email for about a week or so…

P.P.S.: If you want more details on how the debate went, Jonathan Adler has a fairly thorough rundown here. I disagree with his criticism of me, but that’s another story…

P.P.P.S.: DeSmogBlog has a podcast interview with me from Pasadena, as well as another rundown on the debate. Check it out.


  1. #1 etbnc
    June 4, 2006

    Excellent! That’s an important insight, and a very appropriate way to redirect attention where it’s needed.

    Well done.

  2. #2 Ken Goldstein
    June 4, 2006

    Great statement Chris. Can you give us some reporting of what happened at the conference? Some of us too far away to attend would like to know how the conference went (and what some of the speakers said and how they were received).

  3. #3 Vaughan
    June 4, 2006

    Did you hear Strossel and Chrichton speak? How were they received? Have they seen the light, admitted the inconvenient truths?

  4. #4 Laurence Jewett
    June 5, 2006

    Nicely put Chris, particularly the part about Tyndall and the quote by Sagan (who was a skeptic in the true sense of the word, as anyone familiar with his writing (esp. “The Demon haunted World: Science As a Candle in the Dark) lectures and science knows.

    Here’s Sagan’s statement with a “twist”:

    “Extra-ordinary mis-representation of the evidence requires extra-ordinary claims (and extra-ordinary funding)”.

    We have certainly seen more than a little of all three of the latter over the past few years.

  5. #5 anony
    June 6, 2006

    Meanwhile, in case you didn’t see the following:

    Questions About Salmon Are Directed Upstream
    Wednesday, May 31, 2006; A17

    SEATTLE — The Bush administration — having made it hard for federal scientists to talk publicly about global warming — appears to have decided that loose lips are also bad when they talk about salmon.

    “The Washington office of the National Oceanic and Atmospheric Administration — the agency responsible for protecting endangered salmon — has instructed its representatives and scientists in the West to route media questions about salmon back to headquarters. Only three people in the entire agency, all of them political appointees, are now authorized to speak of salmon, according to a NOAA employee who has been silenced on the fish. . . ”

  6. #6 Russell Seitz
    June 7, 2006

    “Apocalyptic predictions require , if they are to be taken seriously , higher standards of evidence than do other matters where he stakes are not so great” said the late Carl, introducing ‘Nuclear Winter ‘ to Foreign Affairs readers on the strength of his own authority in 1983.

    Seven years later , having meanwhile equated NATO tactical nuclear weapons with the >100 million megaton asteroid impact that terminated the dinosaur era , he appeared on Nightline and proclaimed that the Kuwait Oil Fires would collapse the monsoon dooming Asia to famine . It didn’t happen, but Carl was right about one thing- Mr. Jewetts effusion witnesses that man is indeed a myth loving animal.

  7. #7 BenE
    June 9, 2006

    I don’t know Carl Sagan, but I believe his quote is a paraphrase of Laplace (Also a famous astronomer and mathematician).

    “The weight of evidence for an extraordinary claim must be proportioned to its strangeness.” (known as the principle of Laplace. Translated from french)

    Laplace developped modern probability theory. His ideas about probability theory and the scientific method have recently been repopularised by E.T. Jaynes and we are currently witnissing a “Bayesian revolution” in Probability Theory.


    The principle of Laplace only applies to probabilities, however, Jaynes tells us that on top of probability theory there is also the notion of _decision theory_. In decision theory, our decisions are not weighted only on the probability of the outcomes but also on the costs. In the case of global warming, if the failure to act only increase the chance of global environmental destruction and mayhem by a tiny amount, say 1%, there are still very good justifications to do something because the costs are potentially huge. We only have one planet, we have to get it right the first time, there is no second chance. If everytime we put ourselves in situations with just 1% risk of devastation we did nothing, eventually we would succomb.

    It’s like running full speed through red lights in low trafic areas. There’s not that much chance of hitting anything, however, we don’t do it because when we do hit something, it’ll potentially be lethal.

  8. #8 Laurence Jewett
    June 10, 2006

    Looks like I struck a nerve with my comment above that “Extra-ordinary mis-representation of the evidence requires extra-ordinary claims (and extra-ordinary funding)”.

    Someone thought I was directing it at him.

  9. #9 Laurence Jewett
    June 11, 2006

    Chris provides a link above to Jonathan Adler’s take on the Mooney-Bailey debate at the recent Skeptic conference.

    But BEFORE you read that, you might want to read what Adler CLAIMS Cal Tech’s Dr. Tapio Schneider said at the Skeptic conference about the greenhouse effect:

    “carbon dioxide magnifies the greenhouse effect because it absorbs solar radiation”

    Somehow, I SERIOUSLY doubt Dr. Schneider said THAT, since the REAL source of the greenhouse effect is absorption by CO2 (and other gases) of INFRARED (long wavelength) radiation that has been radiated by the EARTH. Dr. Schneider certainly knows this VERY BASIC fact.

    The source of the greenhouse effect is NOT absorption by CO2 of SOLAR radiation. On the contrary, the vast majority of solar radiation (and associated energy) lies in the VISIBLE part of the spectrum, to which CO2 is TRANSPARENT. In other words, the solar (visible) radiation passes right through the CO2.

  10. #10 Barbara Drescher
    June 12, 2006

    You definitely “won” the debate.

    Bailey had a lot of very interesting things to say, but I don’t think you’ll be surprised that an audience member (me) thinks he didn’t actually address the issue of the debate….

    I was very impressed by your debating skills (I was one of those that told you afterwards ;> ) and ability to think on your feet. You’ll go far, I think.

    Congrats on all your successes and please keep fighting on the side of science!

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