Did the IPCC Screw Up Climate Change Policy?

by Julian Ku

I found this interview in Der Spiegel of Fritz Vahrenholt, a German renewable energy executive and a former Social Democratic Party figure fascinating since he doesn’t fit the profile of most climate change skeptics.  Varenholt has a new book coming out, “Die Kalte Sonne” (The Cold Sun), rejecting the IPCC’s global warming models and climate change predictions.

I don’t know what to make of his scientific criticisms of the IPCC models. According to the interview, IPCC models haven’t explained why global temperatures have declined over the last 14 years and have completely ignored the effect of solar activity on global temperatures. It sounds plausible, but what do I know?

I find more interesting his criticism of the IPCC process and how it has lost credibility by making maximalist claims (CO2 causes all climate change and will raise global temperatures by 2 degrees) that it didn’t need to and that undermine its credibilty.

SPIEGEL: Do you seriously believe that all 2,000 scientists involved in the IPCC are deluded or staying true to the official line?

Vahrenholt: It’s not like that. However, I am critical of the role played by the handful of lead authors who take on the final editing of the report. They claim that they are using 18,000 publications evaluated by their peers. But 5,000 of them are so-called gray literature, which are not peer-reviewed sources. These mistakes come out in the end, just like the absurd claim that there will no longer be any glaciers in the Himalayas in 30 years. Such exaggerations don’t surprise me. Of the 34 supposedly independent members who write the synthesis report for politicians, almost a third are associated with environmental organizations like Greenpeace or the WWF. Strange, isn’t it?

The scientific character of the IPCC gives it great credibility and authority.  But it is worth remembering that, like all organizations, the IPCC can be influenced by interest groups. In other words, just because they are scientists, and just because it is an international organization, doesn’t mean they can’t be lobbied.  A lesson worth remembering.


11 Responses

  1. What?  Only 13,000 of the 18,000 articles are peer-reviewed?  What kind of evidentiary basis is that for global warming?  Clearly global warming is just one big hoax orchestrated by Greenpeace and the WWF, who are only out to make a buck — unlike all the denialists, who aren’t influenced at all by the hundreds of thousands of dollars oil companies pay them for their “research.”

  2. My favorite part of the interview:

    SPIEGEL: You make concrete statements on how much human activity contributes to climatic events and how much of a role natural factors play. Why don’t you publish your prognoses in a professional journal?

    Vahrenholt: Because I don’t engage in my own climate research.

  3. I guess I’ll bite too.  Global average temperature has not declined in the last 14 years.  It is virtually impossible to identify statistically significant trends in global average temperature over time frames of less than 17-20 years because the internal variability (noise) overrides the trend (signal).  However, the fact that one cannot conclude that there is a statistically significant positive trend over the last X years is NOT the same as saying the world has been cooling.  That is a logical fallacy.  In fact, if you extend your data back just a few years, the trends become very statistically significant.  In short, the world almost certainly is continuing to warm, you just can’t show statistical significance on short time scales.

  4. I’ll try this too.  Here is a plot of the trends in the five main instrumental temperature records (adjusted to remove as much natural variability as possible) that also shows their errors bars.  As you can see, as the time period shortens, the errors bars increase until (at sufficiently short time spans) the error bars make it impossible to determine whether the trend is distinguishable from zero.  But look at the longer period.  All of them show a strongly statistically significant positive trend.

    The graph as well as an explanation of how it was put together comes from this excellent blog post: http://tamino.wordpress.com/2011/12/06/the-real-global-warming-signal/#more-4517

  5. Of course, the graph didn’t show up in my comment!  That was probably too much to hope for.  If you are interested in seeing the graph, it is the third one down in the blog I linked above.

  6. OK, so 10 years is not  a significant time period but 20 years is. How do you know the 20-year period is significant? You don’t. What you do is claim that you can accurately determine global average temperature within as little as one degree over a 1,000 year period or longer. No one can actually prove you wrong.

  7. Edward,

    I am not sure you really wanted an answer to your question, but I think the standard way to determine the significance of a trend is to run a t-test and then looking up the p-value associated with that t-test result.  That will tell you whether you have sufficient data to determine whether the slope of your regression line is significant or not.

  8. Kevin – The comment about Vernholt not doing his own climate research isn’t really very telling at all, since that’s how the IPCC works.  The IPCC does not conduct any research of its own, none at all, not even the tiniest little bit. It just reviews the literature.  I don’t see why Vernholt’s review of the literature is any less valid than the IPCC’s, or at least, you don’t suggest any reasons to be more skeptical of his views.  Not to mention that one of the major critiques of the IPCC is that a handful of politically motivated folks write the IPCC conclusions – which are all that the press and the politicians read – and ignore any doubts or skepticism mentioned by the real scientists who are then subsumed into the “consensus.”

    But I guess you think that Herr Vernholt is just another paid tool of Big Oil or something, so his rethinking of his views on the AGW hypothesis means nothing.  Well, you’re entitled to your beliefs.

  9. Douglas,

    The IPCC reports are each authored by a large number of experts who actually do conduct research in the field, even if the reports themselves are — by definition — based on meta-analysis of the work of others.  Those reports, moreover, are reviewed by additional panels of experts at least three times during the drafting process.  Vahrenholt, by contrast, simply reads a few articles and offers conclusions on issues outside of his expertise as a PhD in chemistry.

    And yes, I think it’s relevant that Vahrenholt started his career working for Shell.

  10. Climate skepticism on the reasoned and intellectually stimulating blog Opinio Juris? really??
    Oh wait…its Julian Ku.

  11. Respo
    I applaud Fritz Vahrenholt for jettisoning many of his earlier beliefs about climate change and questioning the manmade global warming hypothesis.  He will now face stiff opposition as I once did on a much smaller scale. 
    When I used The Huffington Post’s own figures to point out that the earth’s climate has not been warming since 1998, Arianna Huffington’s website censored me and removed my profile.  You can read about my censorship troubles at my website, Xarkonul, which is available at

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