I must admit that the continual attack on the Cook et al. (2013) Consensus paper is all getting a little tedious. I would have thought that people might have moved on by now. Maybe one could aim the same criticism as me and argue that I too should just let it drop, but it’s hard to simply ignore something that you think is wrong. If you wish to ignore this post, feel free to do so.
The most recent is a Watts Up With That (WUWT) article by Christopher Monckton. The article is called 97% climate consensus denial : the debunkers debunked. As Sou has already mentioned, Monckton’s post is remarkably childish. It’s full of snippy little insults. Refers to the Cook et al. raters as paid schoolboy interns in propaganda studies. Uses terms like brats, zit-faces’. Rather ironic that Monckton refers to himself and his colleagues as the grown-ups and Cook et al. as the kids. Based on the style of this article I would argue that it’s more likely the other way around.
Monckton’s article appears to be based on the recent paper by Legates, Soon, Briggs and Monckton that attempts to debunk the Cook et al. (2013) study. In fact, the Legate et al. paper seems to actually be a comment on an entirely different paper (Bedford & Cook, 2013) but then veers into a discussion of the Cook et al. consensus study. As a basic summary, the Legates et al. paper appears to essentially redefine the Cook et al. study and then point out that they got the wrong answer. Quite a remarkable strategy. You’re wrong because you didn’t do what we thought you should do.
In a little more detail, however, here is the basic premise of the Legate et al. study. The IPPC position is that more than 50% of the warming since about 1950 is due to enhanced greenhouse gas concentrations. Cook et al. had 7 different endorsement categories that they explain quite clearly. These range from explicitly endorse (with quantification), explicitly endorse (without quantification), implicitly endorse, have no position, implicitly reject, explicitly reject (without quantification), and explicitly reject (with quantification). The basic result of the Cook et al. study was that of those papers that stated a position with respect to anthropogenic global warming (AGW), 97.1% endorsed AGW. Legates et al. claim that only those that are explicitly and quantifiably consistent with the IPCC position (that half the warming since 1950 is anthropogenic) can be regarded as endorsements. They find 41 such abstracts (Cook et al. find 64). There were a total of 11944 abstracts rated and hence Legate et al. claim the endorsement fraction is 0.3%, not 97%.
Firstly, and obviously, Legate et al. have decided to include all the abstracts when determining the level of consensus. Why would that be reasonable (and yes, this is a rhetorical question)? Clearly many take no position and hence should not be included in the calculation. There is, I think, a more fundamental problem with the assumptions in Legate et al. Yes, the IPCC position may be that at least half the warming since 1950 was anthropogenic, but it’s also that any future warming will be anthropogenic. There is no scenario in which we can have continued warming that isn’t anthropogenic. There is no known natural process that can produce future warming at the level of 2 to 3 degrees by the end of the 21st century. A large fraction of the abstracts surveyed by Cook et al. considered the future impact of climate change/global warming or whether or not we should mitigate against climate change/global warming. Any abstract that indicated that their model suggested that there would be an impact, in the future, due to global warming is, by default, endorsing the IPCC position. Any abstract that indicated that their model indicates that we should act to mitigate against global warming (or discussed the need to mitigate against future global warming) also endorsed the IPCC position. If AGW is wrong, there is no future warming (or no evidence that we should expect any future warming) and hence there will be no impact and no need to mitigate.
Now, I have a feeling that the Cook et al. raters were quite cautious and didn’t simply rate all impact and mitigation papers – that indicated that there would be an impact or a need to mitigate – as endorsing the IPCC position. I think they actually required that the abstract made a more definitive statement with regards to AGW. As I mentioned in an earlier post I rated 133 abstracts and found a very similar fraction of endorse and no position abstracts as found by Cook et al. (I didn’t find any reject, but only because I didn’t rate enough abstracts).
Now some seem to argue that some of these papers are written by people who are not actually studying if there will be future warming or if the warming since 1950 was mostly anthropogenic. The argument is then that these papers shouldn’t be included because such authors aren’t expert enough to know if the science associated with AGW is right or wrong. The point is, however, that the Cook et al. study was not intended to determine if the science is right or wrong. It was simply attempting to establish the level of consensus in the literature. It’s extremely common to use results from one study in a different study. Those carrying out the new study don’t need to redo all the work from the first study, they simply use the results. Of course they shouldn’t simply use it as a black box. They should understand what it applies to, when it’s appropriate and anything else they need to know to establish if they’re using the results properly. It’s therefore entirely reasonable to use how often something is used in the literature as a measure of acceptance/endorsement. If there are many different models as to how something might work, you’d expect to see that reflected in the literature. Over time, you’d expect certain models to disappear as it becomes clear that they’re not correct and eventually one might dominate. That would indicate the level of endorsement for that particular model.
So, I should acknowledge that I wasn’t involved in the Cook et al. study so really can’t say for certain that there aren’t problems with their result. As I’ve said before, though, this should be established by doing another study, not by trying to pick holes in what they’ve done (especially if this is done by redefining what they did). I should also add that my assessment here is my interpretation of the actual IPCC position and hence why I think the Cook et al. endorsement categories are appropriate. If anyone thinks I’ve interpreted this incorrectly, feel free to comment. It does seem, though, that a lot of the discussion around the Cook et al. study is based on a mis-understanding of the IPCC position. One might hope that this could be cleared up quite easily. One might quite easily be wrong though.