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Broad Irony

Filed under: — group @ 13 March 2007

Michael Mann and Gavin Schmidt

[update 3/20/07: The New York Times has run a short letter from us w/ a link to RealClimate for more info (scroll down to 5th letter; the 2nd letter from James McCarthy of Harvard is quite good too, as are some of the others).]

The first rule when criticizing popular science presentations for inaccuracies should be to double check any ‘facts’ you use. It is rather ironic then that William Broad’s latest piece on Al Gore plays just as loose with them as he accuses Gore of doing.

We criticized William Broad previously (Broadly Misleading) for a piece that misrepresented the scientific understanding of the factors that drive climate change over millions of years, systematically understating the scientifically-established role of greenhouse gases, and over-stating the role of natural factors including those as speculative as cosmic rays (see our recent discussion here). In this piece, Broad attempts to discredit Gore’s “An Inconvenient Truth” by exaggerating the legitimate, but minor, criticisms of his treatment of the science by experts on climate science, and presenting specious or unsubstantiated criticisms by a small number of the usual, well-known contrarians who wouldn’t agree even if Gore read aloud from the latest IPCC report.

Broad starts out by quoting Don Easterbrook (Western Washington University) with a statement,

there are a lot of inaccuracies in the statements we are seeing, and we have to temper that with real data.

Thrown in for good measure is a similarly poorly-supported quote by Kevin Vranes (who is referred to as a climatologist, but who now works on science policy) that

questioned whether his [Gore’s] presentations were overselling our certainty about knowing the future.

Unfortunately, neither Easterbrook’s inaccuracies nor Vranes oversold certainties are mentioned. We reviewed the movie ourselves, looking hard for such ‘inaccuracies’, and could only find one minor area (the explanation of the complex relationship between the global surface temperatures and greenhouse gas concentrations over glacial/interglacial cycles) where justified criticism might be levied (and here, the accusation was only that Gore simplified a complicated relationship, something that is arguably unavoidable in a movie intended for mass popular consumption).

Broad then draws upon the same false dichotomy used previously which seems to equate the mainstream of scientific opinion (that global warming and climate change is real, almost certainly in large part anthropogenic, and likely to lead to substantial and potentially deleterious changes in our environment if no action is taken to reduce greenhouse gas emissions) with “alarmism”, and places contrarians at the very fringe of scientific thinking on an equal footing with mainstream scientists. He goes on to trot out a number of the usual suspects, reciting the usual specious claims and half-truths.

Among the worst, is this one

Mr. Gore, who highlights the devastation of Hurricane Katrina and cites research suggesting that global warming will cause both storm frequency and deadliness to rise. Yet this past Atlantic season produced fewer hurricanes than forecasters predicted (five versus nine), and none that hit the United States.

This is dishonest in at least two different ways. First of all, Broad conveniently forgets to mention that the 2006 Hurricane season was accompanied by a moderate El Nino event. It is well known that El Nino events, such as the 2006 El Nino, tend to be associated with stronger westerly winds aloft in the tropical Atlantic, which is unfavorable for tropical cyclone development. The season nonetheless produced a greater than average number of named storms in the tropical Atlantic (10), 3 more than the typical El Nino year. But El Ninos come and go–more or less randomly–from year to year. The overall trend in named tropical Atlantic storms in recent decades is undeniably positive. We can have honest debates about the long-term data quality, but not if we start out by misrepresenting the data we do have, as Broad chooses to. Additionally, this is a clear misrepresentation of what Gore actually stated in his book. Gore indicated that it is primarily Hurricane intensities which scientists largely agree should be expected to increase in association with warming surface temperatures, and specifically notes that

There is less agreement among scientists about the relationship between the total number of hurricanes each year and global warming.

Next. Roy Spencer, best known for his satellite work arguing against warming of the atmosphere (which turns out to have been an artifact of a combination of algebraic and sign errors), criticizes Gore for pointing out that recent warmth appears to be anomalous in at least the past 1000 years. Spencer does this by both mis-characterizing the recent National Academies Report on the subject which indeed pointed out that there are numerous lines of evidence for precisely this conclusion, and by completely ignoring the recently-released IPCC Fourth Assessment report, which draws the stronger conclusion that the warmth of recent decades is likely anomalous in at least the past 1300 years.

We also find it amusing that Broad takes anything Robert Carter has to say seriously, given that he doesn’t even believe that current rises in CO2 are human caused (judging from his Senate performance). Sea level rise statements from the IPCC Summary are horribly mischaracterised. Easterbrook’s implication that global temperatures have varied by more the 20 times the medieval temperature anomaly over the Holocene is simply laughable (only if you include the deglaciation might that be true, but since that was before the onset even of settled human communities it seems less than relevant).

This article is very disappointing, not just because it gets things so wrong, but because it misses an opportunity to address a much more substantive issue. It is inevitable that working scientists will find popular presentations of their work lacking in depth and nuance (after all, depth and nuance are what we do!). Whatever you may think about Al Gore’s movie, it is indisputable that it has raised awareness of the issues and left a substantial part of the public hungry for more information. That hunger can only be fed by people who are closer to the science than Gore, and it is inevitable that the AIT will be used as a springboard or contrast for further presentations. A better article would have investigated how that is happening and how that is affecting public awareness of the science. Unfortunately, this article does nothing to improve public awareness, and that is deeply ironic.

[Hat tip to David Roberts for pointing out his own article on the Broad piece. David picks up on some additional morsels we left out]

[Update 3/14/07: See also excellent discussions by Tim Lambert and Andrew Dessler]

166 Responses to “Broad Irony”

  1. 151
    Eric Bilsky says:

    Re Broad article and 3/20/07 update:

    The Times did not publish the Mann and Schmidt letter in the print edition I received here in Washington D.C. Was it in any print edition?

    [Response: Unfortunately was in online edition only. Also, they cut some key sentences. Here was the original unedited letter:
    With “From a Rapt Audience, a Call to Cool the Hype” (3/13/07), by William J. Broad, The Times missed an excellent opportunity to explore the difficulties of communicating science in a way that is both accurate but understandable. Instead, Broad misrepresented the state of current scientific understanding on the important issue of human-caused climate change.
    Broad, who accuses Al Gore of scientific cherry-picking in his movie “An Inconvenient Truth”, was ironically the one playing fast and loose with the facts. Broad advances the specious criticisms of a few well-known contrarians who wouldn’t have agreed with Gore had he read aloud from a textbook. We direct readers to our blog RealClimate ( for a scientific review of the movie last May by colleague Eric Steig, which concludes that Gore, on the whole got the science right. A more recent article by the two of us details how Broad on the other hand, got it wrong.
    Dr. Michael E. Mann, Associate Professor and Directory, Earth System Science Center, Penn State University, University Park, PA
    Dr. Gavin A. Schmidt, Research Scientist, NASA Goddard Institute for Space Studies, New York, NY

  2. 152
    Nick says:

    Pricipal Component Analysis.

    Forcings look like factors in a principal component analysis.

    Is the a PCA of historical climate change available?


  3. 153
  4. 154
    Hank Roberts says:

    Have you tried the Search box (white rectangle, top of page) yet?

  5. 155
    Nick says:


    The link is useless. Unless you know what his variables are, you can’t determine anything.

    ‘Variable 1’ dunnit and is guity of all climate change.


  6. 156

    Broad quotes Roy Spencer in his article.

    Roy Spencer seems to base his statement on the data from GRIP borehole (ref. image found on page 5 of report) link below (also ref. to Ural Mountains data – Demezhko and Shchapov, 2001):
    which is at the bottom of the page:

    Roy W. Spencer
    Earth System Science Center
    The University of Alabama in Huntsville
    Huntsville, Alabama 35801

    19 March 2007
    His testimony was submitted to the committee March 19, 2007.

    On page 4-6 Spencer states ” we are now the warmest in 400 years – not 1,000 years” and “Furthermore, actual temperature measurements (not proxies) in Greenland boreholes reveal the Medieval Warm Period (MWP) to be warmer than today” and “claimed to be (estimates of global temperature and carbon dioxide concentrations), then virtually all of the evidence points to the temperature changes leading the carbon dioxide changes — not the other way around – by at least 100 years”

    This image on page 5 shows higher temperature peak around 900 AD. The issues he presents needs resolution in context to be better understood in context of the global mean.

    Could be caused by higher climate variability based on region? The numbers in his report to congress do not match the NOAA/NCDC charts. What is best source ref. for resolved variability of global mean?

    Looking forward to resolution of the incongruity.

  7. 157
    Steve Bloom says:

    As discussed many, many times here, scientists who use the “temperature has historically led CO2” argument to claim that the same must be true for present climate are being intentionally deceitful. As well, Spencer has a long history of being proven wrong on the work he does in his own specialty (satellite sensing of temperature). Finally, he has overtly made himself part of the global warming denial FUD machine. Given all of this, IMHO it’s better to just ignore him.

  8. 158

    Thank you Steve. For clarification are you saying that the image he shows on page 5 of the report is not GRIP but satellite? If not, where did he get this data, or did he make it up?

  9. 159
    Hank Roberts says:

    Assuming the image on p5 is from the cited source (I did not check that but see no reason to doubt it) — nevertheless, it’s from a 1998 paper.

    Someone can put the paper authors and date into Google Scholar and find it, I’m sure.

    There’s more recent work available that would seem proper to also cite.

    This — just for example, from a quick Google Image search —to me is suggestive of some uncertainty in the raw data. Geothermal heating involved, for example, is considered.

    Someone competent in the field can comment; I’m just looking and wondering.

  10. 160
    Anna Haynes says:

    It’s too bad that the Times doesn’t see value in disclosing the affiliations of those whose letters they publish – only Jim McCarthy’s affiliation is provided.
    A quick google reveals Anne Fennell (who was “delighted to read a fairly balanced report in â��From a Rapt Audience, a Call to Cool the Hypeâ��”) to be “our own Anne Fennell” of

  11. 161
    Chris Mooney says:

    At least on hurricanes, Gore is not immune from criticism. However, as Wednesday’s congressional hearings plainly showed, Gore’s “scientific” detractors (aka Barton and Inhofe) use the information far more selectively, even as they show an active disregard for mainstream science–so there’s really no serious comparison

  12. 162
    Hank Roberts says:

    Chris Mooney, that’s praising with faint damn, eh?

    “Gore” — in what you’re writing — might mean the movie at the time it was made, or the movie with several years’ hindsight, or the current content of his slideshow. Criticism of statements is appropriate. Point to the statement you’re criticizing.

    Instead, you’re spinning, and it’s ugly.

    You’re suggesting above that to some, the man himself is “immune from criticism” on most points.

    That’s the “darwinist/hansenist” argument from the anti-science group, making an icon of someone then attacking the icon and claiming the science is bogus on that basis.

    This is the funny smell I keep detecting in the way the NYT approaches Mr. Gore, for years now.
    Why you?

    Bad. Please improve.

  13. 163
    Chris Mooney says:

    Hank your response baffles me. In order to write that post, I went back and watched An Inconvenient Truth and read the hurricane section of the book. Obviously. But when I was quoting I was referring to his congressional testiomony.

  14. 164

    Ok, I’ve doen an analysis of the Spencer argument and related testimony. I would to hear arguments as to content, accuracy and assessment quality.

    It starts about half way down the page.


  15. 165
    Hank Roberts says:

    Chris, if you mean his testimony, point to who would consider what part “immune from criticism” — do you mean specific people in his audience? specific points in his presentation to them? Are you just trying to say he is mostly right most of the time and the scientists don’t find fault with much that he says?

    As you wrote it, you wrote that some people consider Al Gore, the person, “immune from criticism” — which is pretty weird to say, if you’re talking about the science or his interpretation of it.

    Sounded like you mean he has a fan base who think he’s beyond criticism — which is what reminds me of the ‘Darwinist’ and ‘Hansenist’ spin from those who don’t want to address the science from people.

    You’ve probably been clearer elsewhere; what you wrote here is what I commented on, that exact language.

  16. 166
    Hank Roberts says:

    Following up, Chris Mooney was indeed clearer elsewhere; the wording here was unfortunate and atypical.

    And I’m a nitpicker. I hope fellow primates understand it’s meant as a kindness to find and crunch bugs.