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The “97%” Nonsensus

18 Comments

As I noted on Twitter:

Judith Curry explains:

I think we need to declare the idea of a 97% consensus among climate scientists on the issue of climate change attribution to be dead. Verheggen’s 82-90% number is more defensible, but I’ve argued that this analysis needs to be refined.

Climate science needs to be evaluated by people outside the climate community, and this is one reason why I found Kahan’s analysis to be interesting of people who scored high on the science intelligence test. And why the perspectives of scientists and engineers from other fields are important.

As I’ve argued in my paper No consensus on consensus, a manufactured consensus serves no scientific purpose and can in fact torque the science in unfortunate ways.

And José Duarte is appropriately brutal:

My fellow scientists, let’s huddle up for a minute. What are we doing? What the hell are we doing? I’m mostly speaking to climate scientists, so the “we” is presumptuous – I ask for a couple of minutes of your charity. Is this really what we want? Do we want to coarsen science this much? Do we want to establish a scientific culture where scientists must take polar positions on some issue in the field? Do we want to tout a “consensus” that ignores all those who don’t take a polar position? Do we want to import the fallacy of demanding that people prove a negative, a fallacy that we often point out on issues like evolution, creationism, religion, and so forth? Modern scientific culture has long lionized the sober, cautious scientist, and has had an aversion to polar positions, simplistic truths, and loyalty oaths. Do we mean to change that culture? Have we tired of it? Are we anti-Popper now? No one is required to be Popperian, but if we’re replacing the old man, it should be an improvement, not a step back to the Inquisition. Do we want dumb people who have no idea what they’re doing speaking for us? Are we fraud-friendly now, if it serves our talking points? When did we start having talking points?

In any case, what the hell are we doing? What exactly do we want science to be and represent? Do we want “science” to mean mockery and malice toward those who doubt a fresh and poorly documented consensus? Do we want to be featured in future textbooks, and not in a good way? When did we discover that rationality requires sworn belief in fresh theories and models that the presumed rational knower cannot himself validate? When did we discover that rationality requires belief in the rumor of a consensus of researchers in a young and dynamic field whose estimates are under constant revision, and whose predictions center on the distant future? (A rumor, operationally, since laypeople aren’t expected to engage directly with the journal articles about the consensus.) Who discovered that rationality entails these commitments, or even argued thusly? Give me some cites, please. When did we discover that people who doubt, or only mildly embrace, the rumor of a consensus of researchers in a young and dynamic field whose estimates are under constant revision, and whose predictions center on distant future developments, are “deniers”? When did science become a church? When did we abandon epistemology? Again, what are we doing?

The “consensus,” I think, is collapsing. It will be interesting to see the response when Mann’s case is finally thrown out by the appellate court. Particularly if they grant us lawyer fees.

18 thoughts on “The “97%” Nonsensus”

  1. Curry: “overall Verheggen et al. are to be congratulated for the most insightful analysis to date on this.”

    Verheggen’s conclusion? “The punchline is 82% of total respondents agree with the IPCC attribution assessment, with 90% agreement from the scientists most qualified to evaluate this.”

    So 90% of surveyed scientists with at least 10 peer-reviewed, climate-related publications agree with the IPCC on the role of human actions in climate change. Meanwhile, approximately 0% of the Republican leadership agrees with the IPCC on the role of human actions in climate change.

      1. a bullshit study

        Curry writes that “The questions in this survey are far and away the most sophisticated an nuanced that I’ve seen in a survey on this topic” and terms her criticisms of the study “minor”. On the one hand you love to cite Curry as a highly credentialed authority, on the other hand you won’t accept her judgements when they conflict with yours.

        Also, “agree on the role of human actions in climate change” is not “agree that we should wreck our economy to do anything about it.”

        Just getting the GOP to listen to 90-97% of climate scientists on the role of human actions in climate change would be a huge step forward.

        1. I accept her judgment on this. She doesn’t say it’s a good study, just that it’s the best that’s been done. You’re the one mendaciously cherry picking her words and ignoring everything else she wrote.

  2. And she followed that with noting that the selection criteria used “climate change” as a search filter, which shifts the results toward papers from activist scientists and away from scientists writing on the technical aspects of climate physics.

  3. We can quibble about the figures all day. They don’t matter one way or the other. It might matter if there were a clear tendency for majority opinion to be generally correct. However, on the frontiers of science, there is no such correlation.

  5. 82%-90% sounds about right to me. I don’t see any reason to doubt that a very solid majority of climate scientists agree with the IPCC. What I thought was interesting was the approx 30% who thought that the most likely ECS (climate sensitivity to CO2) is at the lowest limit of the IPCC estimates. That is probably only in the last few years, due to people like Nic Lewis, and would take care of much of the problem right there. And almost no one thought it was higher than the central IPCC estimate; the curve was very skewed to the left. That might help make the real disaster scenarios unlikely.

    Anyhow, 85% is very different than 97%. The whole point of 97% is that aside from a few crazies, the science is settled. 85% means 15% don’t agree. We call that an open question in science.
    And as Curry has said, most climate scientists – like most scientists anywhere – don’t know about the parts of the science outside their specialties. She says that she herself considered many issues as settled, then found out that they weren’t when she went to look at them more closely.

    1. Anyhow, 85% is very different than 97%.

      If a sane patient consulted 6 doctors and 5 told him that behavior X was causing his symptoms, and 1 said it wasn’t, he’d reconsider behavior X. Public policy decisions don’t wait for scientific unanimity.

      1. A completely inappropriate analogy. Most of the conditions doctors typically deal with have been tested thoroughly, and cause and effect demonstrated in many controlled experiments. Unless you are dealing with an unusual condition, you would be well advised to listen to the consensus of doctors in such cases.

        As far as the climate is concerned, we only have the one running experiment, and cause and effect have not been demonstrated. You would be as well advised to listen to a consensus of climate scientists there as you would heeding the consensus of doctors pre-1982 as to the cause of your ulcer.

    2. I put the paper’s (pdf) figure 8 into Paint and counted the pixels on the bar chart.

      13.6 percent of respondents thought the ECS (Equilibrium Climate Sensitivity) was 1.5 C or less, 37.7 percent of respondents thought it was 2.5 C or less (which includes the 13.6 percent favoring 1.5 C or less), and 86.6 percent thought it was 3.5 C or less (which includes the prior groups). An ECS of 3.5 C goes with a TCR (Transient Climate Response) of 2 C, which is a more useful number because it takes about a thousand years of time lag to get to the ECS value. And ECS of 2.5 C would give a TCR of only 1.4 C

      Given that we’ve already had 42 percent of a doubling, and putting this in terms of distances, the 37.7 percent of climate scientists who think a doubling of CO2 has an ECS of 2.5 or less means the temperate current climate zones will shift by 70 miles or less, the same as an altitude shift of 570 vertical feet or less. The range favored by 13.6 percent of climate scientists indicates a climate shift of 50 miles or less or an altitude shift of 400 feet or less. The upper limit of 3.5 C, favored by 86.6 percent of climate scientists, would be a climate shift of 100 miles or an altitude shift of 800 feet or less.

      Basically, 86.6 percent of climate scientists predict that I won’t be able to tell any difference, because I absolutely cannot tell where I am, north south to within 100 miles or 800 vertical feet by observing the climate around me.

  7. “Anyone who continues to push “97%” nonsense is either pig ignorant or a lying demagogue. No other options.”

    Rand, you’re wrong, because there’s a third option (one that’s even more likely than the other two); they’re both pig ignorant *and* a lying demagogue. (After all, those aren’t mutually exclusive propositions.)
    :p 🙂

  8. I think it’s telling how much effort has been spent on the “consensus” (including overstating both the degree of consensus and what the consensus is about) instead of trying to argue the merits of AGW theory via actual evidence.

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