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Climate Alarmism vs. the IPCC (did Manzi get what Romm missed?)

By Robert Murphy -- August 2, 2010

The innocent layperson may have gotten the idea that the Intergovernmental Panel on Climate Change (IPCC) represented the “consensus” view that urgent government action is needed to avert catastrophic impacts on humanity.

And yet, as Jim Manzi’s recent exchange with uber-alarmist Joe Romm makes perfectly clear, even the latest IPCC report punctures holes in the alarmist claims. Perhaps without realizing it, Romm implicitly admits that the IPCC AR4 report never supported the alarmist view.

Manzi Uses the IPCC to Take Down Al Gore

In his relatively new position as “in-house critic” at The New Republic, Manzi criticized a characteristically alarmist piece that Al Gore had published in the same venue. Manzi wanted to show that Gore was misleading the public on what the “scientific consensus” actually had to say about the risks of climate change.

First Manzi quoted Gore who had written:

Over the last 22 years, the Intergovernmental Panel on Climate Change has produced four massive studies warning the world of the looming catastrophe that is being caused by the massive dumping of global-warming pollution into the atmosphere.

To which Manzi responds:

According to the IPCC’s currently-governing Fourth Assessment Report, under a reasonable set of assumptions for global economic and population growth (Scenario A1B), the world should expect to warm by about 3°C over roughly the next century (Table SPM.3). Even in the most extreme IPCC marker scenario (A1F1), the best estimate is that we should expect warming of about 4°C over roughly the next century. How bad would that be? Also according to the IPCC (page 17), a global increase in temperature of 4°C should cause the world to have about 1 to 5 percent lower economic output than it would otherwise have. So if we do not take measures to ameliorate global warming, the world should expect sometime in the 22nd century to be about 3 percent poorer than it otherwise would be (though still much richer per capita than today).

Prior to consideration of the more detailed economic issues—e.g., costs versus benefits of attempts to forestall the problem; the danger of worse-than-expected outcomes, etc.—pause to recognize that according to the IPCC the expected economic costs of global warming under the plausible scenarios for future economic growth are likely to be
about 3 percent of GDP more than 100 years from now. This is pretty far from the rhetoric of global destruction and Manhattan as an underwater theme park. [Emphasis in Manzi’s original.]

Manzi is entirely correct: If you wade hip-deep into the actual chapters of the IPCC AR4 report, you will find that yes, most practicing scientists in the relevant fields believe that human activities are leading to climate change, and in particular global warming.

However, you will not find that these trends are pushing humanity towards Armageddon. Contrary to Al Gore’s claim, the IPCC’s latest report does not support the alarmist case.

Joe Romm Punts the IPCC AR4

Of course, Al Gore is not a professional climate scientist. We shouldn’t be looking to him as the standard-bearer of the alarmist position. Instead, let’s see what Joe Romm had to say about Manzi’s critique.

First, Romm quotes extensively from John Bruno, who is “a marine ecologist, Associate Professor at The University of North Carolina at Chapel Hill.” In the interest of brevity, I won’t address each of his responses to Manzi, point by point. Yet if you follow the link to Romm’s post, you will see that Bruno doesn’t dispute Manzi’s numbers per se; he simply says that the IPCC’s official figures leave out many important considerations. (To be clear, Bruno quotes the IPCC report itself on what things it is leaving out of its calculations. So it’s true that the IPCC itself admits its assessments of the dangers of climate change may be understating the risks.)

Then Romm comes back to offer his own, further criticisms of Manzi’s treatment of Gore:

Let me amplify some of Bruno’s points about Manzi’s errors on the science and economics.

If Manzi knows the scientific literature well, he keeps it to himself . The science since the IPCC has evolved considerably, as I review here:  “An illustrated guide to the latest climate science.”  In a AAAS presentation this year, William R. Freudenburg of UC Santa Barbara discussed his research on “the Asymmetry of Scientific Challenge”: “New scientific findings are found to be more than twenty times as likely to indicate that global climate disruption is “worse than previously expected,” rather than “not as bad as previously expected.” It simply isn’t true that 4°C is the worst-case scenario.  Here are two of the best recent analysis of business as usual warming…

Obviously, the sea level rise estimates have jumped in most every recent study (see “Scientists withdraw low-ball estimate of sea level rise and “Sea levels may rise 3 times faster than IPCC estimated, could hit 6 feet by 2100

And if you really want the plausibly worst-case, go here:  UK Met Office: Catastrophic climate change, 13-18°F over most of U.S. and 27°F in the Arctic, could happen in 50 years, but “we do have time to stop it if we cut greenhouse gas emissions soon.”

And that is why scientists led by a former co-chair of the Intergovernmental Panel on Climate Change issued a major report last year concluding the “net present value of climate change impacts” of $1240 TRILLION on current emissions path, making mitigation to under 450 ppm a must

…The areas where the IPCC underestimated adaptation costs include water resources, health, infrastructure, sea level rise, and ecoystems.  Anyway, if you’re interested in the important stuff — the enormous benefit of stabilizing at 450 ppm — just jump to Chapter 8, page 103, here.

For a cost-benefit analysis of just focusing on US legislation, New York University School of Law’s Institute for Policy Integrity demonstrated last year that the Waxman-Markey American Clean Energy and Security Act (H.R. 2454) is “cost-benefit justified under most reasonable assumptions about the likely social cost of carbon.’” In “The Other Side of the Coin: The Economic Benefits of Climate Legislation,” the Institute for Policy Integrity finds that the “benefits of H.R. 2454 could likely exceed the costs by as much as nine-to-one” (see “Waxman-Markey clean air, clean water, clean energy jobs bill creates $1.5 trillion in benefits“).

Now that is certainly an intimidating list of new papers and findings, which would make the average person think that Jim Manzi was out of his league! It looks like disaster really is imminent, after all.

But hold on …. Manzi was NOT arguing, “Governments around the world should do nothing, because the IPCC says there is no threat.” Rather, Manzi was merely pointing out that Al Gore was wrong to claim that the IPCC report justified the alarmist calls for drastic and immediate action.

Ironically, Bruno and Romm implicitly agree with Manzi. Their position is that if you look at all the factors that the IPCC omitted from its analysis, and if you look at the literature that has come out since the AR4 was released, then you will see that the alarmists are correct.

Yet this defeats the whole (ostensible) purpose of having an IPCC process in the first place. The public has been told that the IPCC takes all the divergent views of expert researchers in various fields, and boils them down into a “consensus” that the vast majority of true scientists can support. This will help policymakers make informed decisions, because obviously a politician can’t decide whether Expert A or Expert B is a credible source on the issue.

When all is said and done, the IPCC AR4 report gave the very modest projections that Manzi reported, concerning the benefits and costs from taking government action to arrest climate change. Manzi certainly wasn’t claiming these projections were infallible, he was merely correcting Al Gore’s misleading statement.


The climate alarmists are trying to have it both ways. On the one hand, they use the IPCC as a weapon to bash “deniers” over the head with, claiming that “the consensus” is clear. But then when someone like Jim Manzi comes along and actually reports what the IPCC has to say, the alarmists point out all the shortcomings of the IPCC analysis.

It is certainly true that there are reputable climate scientists and economists who think that the central projections of the IPCC AR4 report are woefully optimistic. But on the other hand, there are reputable climate scientists and economists who believe its conclusions are woefully pessimistic, and that humanity will be just fine even if governments do nothing to impede emissions.

To repeat, the whole point of having an IPCC was to consolidate these divergent views into a “consensus” that most experts could get behind, and that policymakers could take as a firm foundation for making their legislative decisions. As Manzi has tirelessly documented, the latest IPCC report does not support the case for climate alarmism.


  1. Andrew  

    “New scientific findings are found to be more than twenty times as likely to indicate that global climate disruption is “worse than previously expected,” rather than “not as bad as previously expected.”

    In any other field, I would expect scientists to step back and say “something is not right here”. This would almost certainly be interpreted as evidence of publication bias. Indeed, according the Battisti et al amicus curae brief of the “consensus” scientists, the probability that future results show worse outcomes is equal to the probability that they show less bad ones, so the finding that “worse than we thought” prodominates is counter to the expectations of many prominent members of the scientific community. So there are two possibilities here: either the science has been stuck in an erronerous paradigm for decades, which it would need to rapidly emerge from at the phase were evidence showing the errors is really piling up, or there is a HUGE bias in publication towards catastrophist type results. Now, if I were to argue that the paradigm is indeed wrong, but in the opposite direction, that would be suggested to be absurd (“they are scientists, how can they be wrong? How can so many be so wrong for so long?”)-but when you want to argue that the paradigm is all wrong, it’s not nearly catastrophic enough, that’s okay. Only because the papers are leaning heavily that way? Oh. I see. But it couldn’t possibly be publication bias. Nope.


  2. Murphy Triple Play  

    […] At MasterResource I show how the climate alarmists punt the IPCC whenever Jim Manzi quotes from […]


  3. Damned Skeptic  

    I wonder if Mr. Romm realizes that his claim to know what “the science” is negates the need for the IPCC? Why put all the money and resources into the IPCC when the science can be determined by one guy? If I was a betting man, I’d put my money on Mr. Romm not actually having any evidence to back up his claim of knowing what the science is now. That’s the problem with claims about AGW consensus or knowing “the science”. The evidence consists of a few inadequate studies, statements of scientific organizations and personal belief.


  4. Charles  

    I find that CO2 driven global warming is something that is not to well understood by the proponents.

    If we took a 40m x 20m glasshouse, with a roof composed of 2500 approx. 2 ft x 1 ft glass panes (excuse the mix of metric and imperial), then only one of those panes would be the CO2 one. Does anyone think it likely that one defective pane that stops radiation from being emitted from the glasshouse be likely to change the temperature of such a large area, or overwhelm the effect of the vast majority of other ‘normal’ panes? Not likely.

    Even worse, the anthropogenic component of CO2 would mean that we have control of only about 10 sq ins of that single pane of glass. So I am wondering when someone says we can keep global warming rises to less than 2 C if we can reduce anthropogenic emissions, do they really know what they are talking about?


  5. Ed Reid  


    I believe the “less than 2C” is a wish. Pick an IPCC model projection and you can “define” an atmospheric concentration which might limit temperature rise to 2C. However, 2C is not a goal. There is no plan. There is no commitment. I seriously doubt there is even any degree of confidence in the wish being granted. It’s kind of like a letter to Santa.

    “A goal without a plan is just a wish.”, Antoine de St. Exupery


  6. stickman  

    A good post Bob… And a fair point made about “trying to have it both ways”.

    Personally, I find Jim Manzi the most refreshing “conservative” climate change commentator around. Unless I have missed something, I also find that he is always respectful of those he is debating with… Romm’s tirade against Manzi was in poor taste.

    That being said, it does seem the Romm has raised a fair point w.r.t. Manzi’s misinterpretation of Marty Weitzman’s fat-tail argument. That is, Weitzman is focusing on the damage function along the probability distribution, rather than the probability distribution itself.


  7. Craig Goodrich  

    As a matter of strict fact, the IPCC’s AR4 doesn’t even present any evidence that the warming of the last quarter of the 20th century was due to CO2 at all. Careful reading of WG I, Ch. 9 reveals that the only argument for this hypothesis is exactly what it was two decades and $100 billion ago: “The models can’t account for the warming without putting in CO2.”


  8. stickman  

    Craig, I’m not sure what you’re getting at.

    From what you have written, it seems fairly obvious to me that the IPCC is simply saying that they have steadily been ruling out all other possible culprits for the observed warming (solar activity, etc)… bar CO2.

    In other words, based on present knowledge only increases in CO2 can plausibly account for the rise in temperature over the last quarter century (and, indeed, since some time before that).


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