Claim: There is no 97% climate consensus

It seems like a fairly well known advocate for the use of fossil fuels, Alex Epstein, has published an old 2015 Forbes article (yah, I'm beating another dead horse again) postulating that there is no 97% consensus on anthropogenic global warming.

Epstein writes:
Here are two questions to ask anyone who pulls the 97% trick.

1. What exactly do the climate scientists agree on?

Usually, the person will have a very vague answer like "climate change is real."

Which raises the question: What is that supposed to mean? That climate changes? That we have some impact? That we have a large impact? That we have a catastrophically large impact? That we have such a catastrophic impact that we shouldn't use fossil fuels?
To answer Epstein's question that certainly wasn't made in bad faith, we shall turn to a 2014 survey of the American Meteorlogical society by Stenhouse et al. and correct him by saying that climate scientists agree that global warming is occurring and that it is predominantly driven by humans. To quote Stenhouse et al.
Climate science experts who publish mostly on climate change and climate scientists who publish mostly on other topics were the two groups most likely to be convinced that humans have contributed to global warming, with 93% of each group indicating their concurrence.
In addition, Stenhouse et al. noted that greater expertise in climate science predicted a greater likelihood that anthropogenic global warming is harmful, though the perception of consensus was the strongest contributing variable:
Confirming all four hypotheses, the regression analyses showed that greater expertise, more liberal ideology, greater perceived consensus, and lower perceived conflict each predicted higher levels of certainty global warming was occurring, higher likelihood of viewing it as mostly human caused, and greater ratings of future harm. Together, the independent variables explained 37% of the variation in certainty that global warming is occurring and 29% of the variation in views on global warming harm.
Unfortunately, Stenhouse et al. didn't give a precise percentage of the scientists who thought global warming would be harmful, but his findings still do cast doubt on Epstein's thesis and agenda. But Epstein still claims the following in ignorance of Stenhouse et al.'s findings.
What you'll find is that people don't want to define what 97% agree on--because there is nothing remotely in the literature saying 97% agree we should ban most fossil fuel use.
Epstein then makes the following statement:
If you look at the literature, the specific meaning of the 97% claim is: 97 percent of climate scientists agree that there is a global warming trend and that human beings are the main cause--that is, that we are over 50% responsible. The warming is a whopping 0.8 degrees over the past 150 years, a warming that has tapered off to essentially nothing in the last decade and a half.

uncaptioned Sources: Met Office Hadley Centre HadCRUT4 dataset; Etheridge et al. (1998); Keeling et al. (2001); MacFarling Meure et al. (2006); Merged Ice-Core Record Data, Scripps Institution of Oceanography
The first fallacy that Epstein commits is the implication that the effects of warming can't be significant because 0.8 degrees of warming is a relatively small amount. This is both an appeal to intuition and an argument from personal incredulity. Just because one cannot intuitively conceive of how such a small change in warming could have a significant effect does not mean it can't have such an effect. An increase in the blood alcohol level from 0% to 0.4%, according to Healthline, may seem like a small number, but it still doesn't mean it isn't lethal.

The second fallacy that Epstein commits is claiming that the warming has ceased in the last decade from 2015. This is another example of the cherry picking fallacy, which is a common climate contrarian tactic: select tiny periods where warming has stopped or ceased and use that to prove that the warming is non-existent, or not CO2 driven. Well then by that logic, it must therefore be the case that divorce rates in Australia are increasing because they increased within a few years after Y2K:
The reason why cherry picking tiny periods of data to infer a longer trend is faulty is, as everyone surely knows, because real life trends rarely are linear.

The third fallacy that Epstein commits is that of distorting the visual representation of the data in two manners. Though the main critique of this graph comes from a software developer by the name of Sam Fiddis on his blog, I still feel it is a valid critique overall and I will briefly summise it as follows:
  1. Epstein deliberately used a differing aspect ratio for the grid of the temperature graph than for the CO2 graph, which makes the warming trend look flatter than it really is as to make the CO2 and temperature trend seem out of sync with one another.
  2. Epstein also deliberately cut off the CO2 graph at 275ppm mark to eliminate any empty space underneath the trend line, while leaving the same empty space beneath the temperature trend intact to give the illusion that the latter is flatter
  3. Epstein deliberately and arbitrarily connected the successive record temperature highs and lows with dotted lines to give the illusion that the trend fluctuates more than it actually does. If he were to draw a proper line of best fit for each arbitrarily long section he connected, they wouldn't link up with each other at all.
Or to put it this way, if he were to properly draw a line of best fit in the graph, this would be the result:
And if he were to keep the grid aspect ratio the same between the two graphs, this would be the result:
And if we were to look at the source for his data from the Met Office Hadley Centre (or HadCRUT4) and many other reputable sources, we get this graph:
And if we look at the updated HadCRUT5 from the same source, we get this:
Both dataset, as observed, show a much more glaring and consistent warming trend than Epstein's graph does. So Epstein is either dishonest, or dumb, or both, and I will be continuing this in the next post.


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Senior Member.
The zigzag "temperature anomaly" trend line is so unusual that I feel confident it's a deliberate attempt to mislead. No source using this uncritically is trustworthy, either because they're malicious, or because they have no clue (or both).


Senior Member.
Yeah, I'm sure what remains of mankind, will, as the planet becomes uninhabitable
and the human race dies a slow tortuous (self-inflicted) death, they'll be cheered by
a declaration that "It was only 95.7% of climate scientists who repeatedly warned us."


Senior Member.
The zigzag "temperature anomaly" trend line is so unusual that I feel confident it's a deliberate attempt to mislead. No source using this uncritically is trustworthy, either because they're malicious, or because they have no clue (or both).

I agree, buuut.... after reading too many financial charts, what that emphasises to me is "higher highs and higher lows", and every technical analyst in the world will conclude that's very good evidence for there being an underlying upward trend. So it almost acts against his case, if viewed with the right mindset! (But yes, it's still inappropriate.)


Senior Member.
The zigzag "temperature anomaly" trend line is so unusual that I feel confident it's a deliberate attempt to mislead. No source using this uncritically is trustworthy, either because they're malicious, or because they have no clue (or both).
I always hate it when graphs are used (in media) that have no error bar or even a statement of uncertainty. It happens more often then not, and apparently nobody cares (not even the journalists etc).
But agreeing datasets taken using completely different methods (satellites, probes etc), is very convenient.

Amber Robot

Active Member
Yeah, I'm sure what remains of mankind, will, as the planet becomes uninhabitable
and the human race dies a slow tortuous (self-inflicted) death, they'll be cheered by
a declaration that "It was only 95.7% of climate scientists who repeatedly warned us."
A man was having constant headaches, piercing pain. He went to a doctor, who told him he had an inoperable brain tumor and was going to die. He didn’t like that prognosis so he went to another who said the same thing. Then another. And another. Eventually, 19 doctors all told him he had a brain tumor and was going to die. But then he found a 20th doctor who said he didn’t think it was a tumor and the man said, “phew! I knew it was nothing to worry about!”
Moving on...

Epstein proceeds to dedicate another section to debunking John Cook's 2013 paper demonstrating that 97% of abstracts that express an explicit position on the reality of global warming endorse the position that it is anthropogenic, or man-made. He starts off by stating that:
Here is Cook’s summary of his paper: “Cook et al. (2013) found that over 97 percent [of papers he surveyed] endorsed the view that the Earth is warming up and human emissions of greenhouse gases are the main cause.”

This is a fairly clear statement—97 percent of the papers surveyed endorsed the view that man-made greenhouse gases were the main cause—main in common usage meaning more than 50 percent.

But even a quick scan of the paper reveals that this is not the case. Cook is able to demonstrate only that a relative handful endorse “the view that the Earth is warming up and human emissions of greenhouse gases are the main cause.” Cook calls this “explicit endorsement with quantification” (quantification meaning 50 percent or more). The problem is, only a small percentage of the papers fall into this category; Cook does not say what percentage, but when the study was publicly challenged by economist David Friedman, one observer calculated that only 1.6 percent explicitly stated that man-made greenhouse gases caused at least 50 percent of global warming.
In case anyone didn't know, this is the article that Epstein was referring to that cited the 1.6% figure. Epstein follows by stating that:
Where did most of the 97 percent come from, then? Cook had created a category called “explicit endorsement without quantification”—that is, papers in which the author, by Cook’s admission, did not say whether 1 percent or 50 percent or 100 percent of the warming was caused by man. He had also created a category called “implicit endorsement,” for papers that imply (but don’t say) that there is some man-made global warming and don’t quantify it. In other words, he created two categories that he labeled as endorsing a view that they most certainly didn’t.
Now Epstein is clearly trying to make it seem like Cook et al. only created non quantitative explicit and implicit endorsement categories without also doing the same for positions rejecting AGW via omitting key details of the study. If we look at the criteria for endorsement vs rejection of Anthropogenic Global Warming (AGW) as articulated by the paper, we notice that Cook et al. apply the same set of metrics they do to studies endorsing AGW (Levels 1-3) to those rejecting AGW (Levels 5-7):
What this means is that contrary to what Epstein implies, any paper that quantifies the anthropogenic forcing as being less than 50% will always be classified as a paper that rejects the consensus; and even if a paper doesn't quantify how much warming humans are responsible for, per the methods of Cook et al., the paper will still be classified as a paper that rejects the consensus if it either explicitly says that AGW is not supported by the evidence, or implies that natural mechanisms are the primary cause of most of the warming. This is henceforth a good example of lying by omission.

That aside, Cook et al. merges the first and last three categories on the chart above as follows:
To simplify the analysis, ratings were consolidated into three groups: endorsements (including implicit and explicit; categories 1–3 in table 2), no position (category 4) and rejections (including implicit and explicit; categories 5–7).
Thus they come to the following results on the degree of agreement on consensus:

Screen Shot 2022-02-07 at 11.30.06 pm.png
This is where the 97% figure comes from, and as you notice that as an aggregate, all studies rejecting AGW from categories 5-7 are included here. Which brings us onto the article Epstein mentioned where he got his 1.6% figure from: a website promoting libertarian economics called Econlib. According to their analysis of Cook et al.'s raw data, only 64 out of 11,000+ papers, or 0.5% of all papers analysed, or 1.6% of all the papers expressing a position on AGW explicitly endorse and quantify AGW, or 0.5% of all papers. But they then quantify the total number of papers rejecting and quantifying AGW as being only 9 out of 11,000+ papers, or 0.07% of all papers. Divide 9/64 and you get 14% of papers rejecting AGW, and hence an 86% consensus, which is still pretty damn large. But that aside, the article engages in some rather deceptive framing of the methodology as follows:
So 64 out of 11,944, or 0.5%, take the view that humans are the main cause of global warming... The 64 who think the main cause is humans is, drum roll please: 1.6%.
Notice something? The article framed the 1.6% as the scientists who think AGW is real, when it is only the number of papers endorsing and quantifying the impact of AGW, rather than all papers that endorse AGW - as indicated by their use of language in support of it - but don't have anything quantifying the degree of AGW above 50%. This is not the same as not quantifying the degree of AGW at all, either above or below 50%. In addition, Cook et al. conducted another survey by directly asking the authors of the studies assessed to rank them on the same 1-7 scale that was used:
In a second phase of this study, we invited authors to rate their own papers. Compared to abstract ratings, a smaller percentage of self-rated papers expressed no position on AGW (35.5%). Among self-rated papers expressing a position on AGW, 97.2% endorsed the consensus. For both abstract ratings and authors' self-ratings, the percentage of endorsements among papers expressing a position on AGW marginally increased over time. Our analysis indicates that the number of papers rejecting the consensus on AGW is a vanishingly small proportion of the published research.
Hence not only did less of the papers ranked by the authors state a position on AGW, but 97% still came out in support of it.

So the verdict is: Epstein isn't technically wrong, but nevertheless still present Cook et al.'s thesis in a manner that is misleading, and hence he is still dishonest.

EDIT: I have also noticed that Econlib made the following comment on Cook et al.
Unfortunately, in their data set, Cook et al put 4a, those that do not address the cause of global warming, with 4b, those that express the view that humans’ role in global warming is uncertain or undefined. It would be nice to separate them, but we can’t unless we have the even rawer data.
Even though I will grant for now that this statement is technically true, it is once again a form of lying by omission. How? Because if you look at Cook et al.'s results as outlined above, they do separate the papers that have no position vs those that adopt a stance of uncertainty.

To be continued...


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Senior Member.
You shouldn't be counting abstracts, you should be counting scientists. Otherwise you're imposing an gameable weighting function on the value of each scientists' opinion. Worse, one that is shapeable by the opinions of only a few scientists who can act as gatekeepers on editorial boards. There's a clue in the word - consensus requires sentience, not double-spacing.
After looking at Cook et al's study again, they did mention that in order to qualify as at least implicitly rejecting AGW, let alone explicitly, it requires a paper to only say that a major portion of global warming is manmade as indicated in Level 5 in the methods screenshot. However, a major portion is not necessarily a majority, as it generally means just a significant portion, which doesn't have to be a majority. So I think this might lend credence to Epstein's claim somewhat. But then again, I believe that endorsement means merely acknowledging that measures to cut carbon emissions are necessary, which implies that humans have a significant enough warming impact that cutting emissions matters. So whaddya think of my attempt at devils advocate?


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However, a major portion is not necessarily a majority, as it generally means just a significant portion, which doesn't have to be a majority.
Is this covered by the actual ratings? because I'd read this differently, with anthropogenic causes being more important than natural causes.

And then there's the self-rating part of Cook 2013:

To complement the abstract analysis, email addresses for 8547 authors were collected, typically from the corresponding author and/or first author. For each year, email addresses were obtained for at least 60% of papers. Authors were emailed an invitation to participate in a survey in which they rated their own published papers (the entire content of the article, not just the abstract) with the same criteria as used by the independent rating team.

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So that's 97% as well.