Matt Ridley and the Wall Street Journal misrepresent paper cited in Ridley column

Equilibrium climate sensitivity (ECS) evaluated from paleoclimatic data (PALAEOSENS group, Rohling et al., 2012).

There’s more to say about the latest attempt to deny the mainstream estimate of equilibrium climate sensitivity (e.g. NRC, 1979; Annan and Hargreaves, 2006; Knutti and Hegerl, 2008; Rohling et al., 2012) by Matt Ridley (remember him?) at the Wall Street Journal later. But I just wanted to point out something rather troubling about one of Ridley’s and Nic Lewis’s (the source of Ridley’s claims) citations.

Ridley claimed:

Some of the best recent observationally based research also points to climate sensitivity being about 1.6°C for a doubling of CO2. An impressive study published this year by Magne Aldrin of the Norwegian Computing Center and colleagues gives a most-likely estimate of 1.6°C.

I recalled the Aldrin et al. paper from the last time it made the rounds in the “skeptic” blogosphere, when Chip Knappenberger cited it as finding a “low” climate sensitivity.

The funny thing about the Aldrin et al. paper is that it really doesn’t find a “low” ECS at all. Their main result is an ECS of 2.0°C, which is completely consistent with the IPCC AR4 range. Moreover, they caution that their main result is incomplete, because it explicitly does not account for the effect of clouds:

When cloud behavior is included as another term, the ECS increases significantly, from ~2.5°C to 3.3°C depending on the values used:

Surely this wasn’t the Aldrin et al. paper Riddley and Lewis were citing as finding an ECS of 1.6°C.

The 1.6°C value literally never appears in the text of the paper.

Of course, it was entirely possible that Aldrin had published another paper on ECS this year finding 1.6°C that I was simply unable to find. I reached out to Bishop Hill and Matt Ridley for some clarification:

  1. thingsbreak
    @aDissentient Which Aldrin 2012 paper was Lewis citing on your blog?
  2. thingsbreak
    @mattwridley Can you provide either the title or the DOI for the Aldrin paper you cited in your WSJ piece? Thanks!
  3. aDissentient
    @thingsbreak Environmetrics 2012; 23: 253–271 Panel A of Fig 6.
  4. thingsbreak
    @aDissentient The one that finds an ECS of 2.5-3.3K when it bothers to account for clouds (4.8)? LOL.
  5. mattwridley
    @thingsbreak… Aldrin, M., et al., 2012. Bayesian estimation of climate sensitiv… Environmetrics, doi:10.1002/env.2140.
  6. thingsbreak
    @mattwridley Did you personally read the paper? Where does the 1.6 number come from? Did you read section 4.8?
  7. aDissentient
    @thingsbreak Most likely values still only 2 ish. If we are to include cloud lifetime effect shld we include other highly uncertain effects?
  8. thingsbreak
    @aDissentient If you’re making a comparison to IPCC values, should use most apples-to-apples comparison, which Aldrin et al. discuss in 4.8.
  9. thingsbreak
    @aDissentient Where does the 1.6 value come from anyway? Literally doesn’t exist in paper.
  10. aDissentient
    @thingsbreak He got it by measuring the graph (It’s actually slightly lower I believe).
  11. mattwridley
    @thingsbreak lewis calculated it from aldrin’s paper’s data/charts and aldrin agreed it is correct
  12. thingsbreak
    @mattwridley Aldrin agreed that apples to apples comparison with IPCC ECS estimates is 1.6K? Doubtful. Directly contradicts paper itself.

I posted the following to Nic Lewis at Bishop Hill’s blog:

I think that some readers, and probably the authors of a paper themselves, might find it at least slightly misleading for you to claim findings on their behalf that the paper itself does not actually state.

The main result from Aldrin et al., as reported by Aldrin et al., is an ECS of 2.0°C. The authors caution that this result probably isn’t an apples to apples comparison to other ECS estimates due to the unaccounted for cloud term, and find that the value increases to ~2.5-3.3°C with clouds.

Rather than report either of these values, you simply claim Aldrin et al. “an impressively thorough study, gives a most likely estimate for ECS of 1.6°C…”.

Ridley likewse claims, “An impressive study published this year by Magne Aldrin of the Norwegian Computing Center and colleagues gives a most-likely estimate of 1.6°C.”

It would be easy for me to lob accusations of bad faith, as we don’t know each other and this is just the internet. Instead, I would encourage you, if your goal is to reach as wide an audience as possible, and try to make an impact beyond the “skeptic” and conservative blogospheres, to be more upfront about the scientific literature about ECS.

Ignoring the two main findings of a paper for values that you’re either estimating from a curve or are creating yourself based on data not used by the paper will be seen by at least some people to be misleading. Claiming that ECS cannot be estimated by paleo data is absurd, especially when so many are aware of efforts like the PALAEOSENS project and various paleoclimatic intercomparison groups.

I won’t attempt to read minds or divine motivations. I will simply suggest that what you have been doing thus far will cause some people to dismiss what you’re trying to say due to perceived dishonesty.

I hope you take this criticism in the constructive context in which it is being offered. There will be plenty of time for name-calling and insults later.


  • Aldrin, M., M. Holden, P. Guttorp, R. B. Skeie, G. Myhre, and T. K. Berntsen (2012), Bayesian estimation of climate sensitivity based on a simple climate model fitted to observations of hemispheric temperatures and global ocean heat content, Environmetrics, 23(3), 253–271, doi:10.1002/env.2140.
  • Annan, J. D., and J. C. Hargreaves (2006), Using multiple observationally-based constraints to estimate climate sensitivity, Geophys. Res. Lett., 33, 4 PP., doi:200610.1029/2005GL025259.
  • Knutti, R., and G. C. Hegerl (2008), The equilibrium sensitivity of the Earth’s temperature to radiation changes, Nature Geoscience, 1(11), 735–743, doi:10.1038/ngeo337.
  • National Research Council (1979),  Carbon Dioxide and Climate: A Scientific Assessment. Washington, DC: The National Academies Press.
  • Rohling, E.J., et al. (2012), Making sense of palaeoclimate sensitivity, Nature, 491(7426), 683–691, doi:10.1038/nature11574.

12 responses to “Matt Ridley and the Wall Street Journal misrepresent paper cited in Ridley column

  1. So who is telling lies here, Montford, Ridley or Lewis, or all three of them? ;)

  2. That would fit. Matt Ridley and the Wall Street Journal also misrepresent the paper on the NASA NVAP global humidity dataset and acted as if this paper claimed that humidity does not increase.

    The truth is that the authors did not try to study the water vapor trend.

    They did not do so because the dataset is currently only suited to study “seasonal to interannual variability” due to inhomogeneities in the dataset. For example, because the types and number of satellites changed during the observation period. But Mims knows better than the authors and does not feel the need to say that the authors of this paper do not agree with his original science without arguments.

    Furthermore, what they did not mention is that this dataset is only 23 years long and thus not interesting for trend analysis as the uncertainty would be huge anyway, even if the dataset would not be biased.

    Another clear piece of misinformation, that “will cause some people to dismiss what [Ridley is] trying to say due to perceived dishonesty.” Looks like the problem in this blog post is not a coincidence.

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  4. “If we’re correct it will make it easier (to slow global warming) but it will still require dramatic reductions in emissions,” said Terje Berntsen, a professor at the University of Oslo and an author of the report. A doubling of the concentration of carbon dioxide in the atmosphere over pre-industrial times would push up temperatures by between 1.3 and 2.9 degrees Celsius (2.3-5.2 F), it said.
    LESS WARMING? That is below a range of 2.0 to 4.5 degrees C (3.6-8.1 F) estimated as the likely response to a doubling of carbon dioxide in a 2007 report by the U.N.’s Intergovernmental Panel on Climate Change (IPCC). Berntsen’s report is under review by the Journal of Climate”

  5. Anyone have a link to the Lewis paper. BTW the good bishop took the scissors to your post.

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  7. Excerpts from the most recent 2 posts over there as of now:

    “The problem was not that is was non-science but that it was likely to provoke a food fight.” — Bishop Hill

    “…. new paradigm explaining planetary surface temperatures.”
    — Doug Cotton
    Clear enough the BH blog rules are.
    Posting non-science there is OK.
    Arguing with non-scientists there is not OK.

  8. There is some confusion here:

    1. Matt Ridley talked about a “most-likely estimate” of 1.6°C. Most likely is at the maximum value of the probability function which is 1.6 °C. You are referring to the mean value, which is 2.0 °C. This are jut different parameters.

    2. “Adding an extra component to the radiative forcing.”
    The main study includes aerosol forcing taken from AR4. The study then continues under the assumption that this data is not complete (e.g the very poorly uinderstood cloud lifetime effect is missing) and aerosol coolng was underestimated.
    However, the leaked AR5 report shows, that aerosol cooling has not been underestimated but instead overstated by a massive 40%. That would now require a rather significant further reduction of the sensitivity.

    On top of that, forcing from black soot has also been revised upwards in a recent landmark study, requiring an additional significant reduction of the sensitivity.

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