I'm a "climate denier." Or a "climate blogger." Or something. Nobody seems to know. I'm not even sure what a "climate denier" would be, and I still cringe at the idea of being a "blogger." The reason I say this is there was recently a
Press Complaints Commission (PCC) ruling which cited a couple of the posts I've written here. When it referred to me, it gave the footnote:
Brandon Shollenberger is described by some as both a “climate blogger” and a “climate denier”. He has published a number of online critiques including a negative critique of Dana Nuccitelli’s work.
This ruling bears on the long running controversy I've been somewhat involved in regarding Richard Tol and the changes he made to the latest IPCC report. People who follow my writing will remember this controversy built to the point I submitted a formal complaint with the IPCC in January. I still haven't received a response regarding it. I find that troubling, and I've tried following up on it, but so far I've had no luck.
In any event, the PCC ruling was made regarding complaints by Richard Tol about articles written by his critics. Tol claimed these articles were highly misleading, part of a "smear campaign" and amount to harassment. The PCC ruled against Tol on over a dozen specific claims, finding only one of his minor complaints had any merit.
Unfortunately, This hasn't resolved anything. There has been no resolution of the scientific issues underlying this controversy. Last week, Richard Tol published an article criticizing an article written by one of his critics, Bob Ward. In it, he says:
Mr Ward claims that there are "significant errors in [a] study suggesting global warming is good for the world". That study is a survey published by me in 2009. There were errors in that survey, now corrected, but the headline conclusions did not change. The latest survey contains four studies - by the late Ralph d'Arge, Robert Mendelsohn of Yale University, David Maddison of Birmingham University and myself - that conclude that climate change would improve human welfare. None of these studies have been found to be in error.
For some reason, this is a central issue in the controversy. Richard Tol received a significant amount of media attention and support from global warming "skeptics" after he published several papers claiming to show moderate global warming will be beneficial for the world. He got this result by looking at papers people had published on the issue and combining their results.
The problem is almost none of these results supported his claim. This wasn't apparent at first because there were many data errors in Tol's work, errors which made it appear more data supported his conclusions than actually did. This includes results from two papers which found global warming will be harmful which Tol somehow listed as finding global warming will be beneficial.
Tol refers to these errors and some corrections of them, saying:
Mr Ward highlights "shortcomings in the trend that [I] had fitted to the data". In fact, the original and corrected data are not materially different. There is no statistically significant difference between the trends fitted to the original data and to the corrected data.
This is somewhat true, but mostly misleading. Not all of the problems with the data were fixed, but it is true the "trends fitted" were not materially different. This can be seen in a figure comparing the two trend lines:
However, this figure shows there is a significant problem: almost no data supports Tol's conclusions. The figure shows only one data point which suggests any sizable benefit from global warming. There's another data point, but it is so barely positive (0.1%) it is almost irrelevant.
To make matters worse, the one data point showing any sizable benefit from global warming was taken from Tol 2002, a paper written by Richard Tol himself. That means once a number of data errors were corrected, Tol's only support for his "headline conclusion" was a paper he himself published. His trend lines were unaffected by this, but trend lines dependent entirely upon a single outlier are obviously incorrect (and due to a simple statistical artifact). This is particularly noteworthy because Tol's original paper studying this data said:
it is striking that the estimates are in broad agreement on a number of points—indeed, the uncertainty analysis displayed in Figure 1 reveals that no estimate is an obvious outlier
In any event, as time passed, more data was added to the analysis. The first quote I provided from Tol in this post says there are now four studies which support his conclusions. One of them is Tol 2002. Another is by Robert Mendelsohn, which is the barely positive data point at 0.1%.
The other two are... I don't know. It appears they might be figments of Tol's imagination. Tol claims the "latest survey contains" studies by Ralph d'Arge and David Maddison "that conclude that climate change will improve human welfare." These studies are not present in any of the work which has been discussed. This is a table of the studies used by Tol for the IPCC report:
Maddison is listed as an author on three studies, all of which find negative effects from global warming (at -0.1%, -0.4% and -12.4%). The same studies are listed with negative effects in a recent paper by Tol (though strangely, the exact values are not the same). There is no apparent explanation for why Tol claims a study by Maddison finds global warming "will improve human welfare" when his own published data sets show the opposite.
There is also no apparent explanation for why Tol claims a study by Ralph d'Arge shows anything. No work by him was used in any of Tol's work that has been discussed. It wasn't even used in his more recent paper. Maybe some survey exists somewhere which shows what Tol claims, but if so, it has never been cited in any discussion so nobody reading Tol's article could possibly know what he's talking about. As far as anyone can tell, Tol may simply be making things up. He certainly is when he says:
Since 2009, however, more estimates of the economic impact of climate change have been published. These new results do affect the fitted trend, but not in the way suggested by Mr Ward. The new trend shows positive impacts for warming up to about two degrees global warming, just like the old trend did. The new trend, however, shows markedly less negative impacts for more profound warming than did the old trend. In other words, in the last five years, we have become less pessimistic about the impacts of climate change.
A correction Tol was forced to publish to his work shows this is untrue. This is the figure Tol published after correcting (some) data errors and adding new data:
There is no benefit from global warming shown in this figure. Richard Tol himself even acknowledged this in his correction, saying:
I nonetheless highlight two differences between the old and the new results. First, unlike the original curve (Tol 2009, Figure 1) in which there were net benefits of climate change associated with warming below about 2°C, in the corrected and updated curve (Figure 2), impacts are always negative, at least in expectation.
Tol's recent article claims a critic of his, Bob Ward, is wrong for saying the same thing Tol himself published in a scientific journal not even a year ago. How can Tol claim saying the same thing as he says makes you wrong? I don't know. Tol doesn't offer any sort of reference or explanation for his claims in his article. Apparently readers are supposed to just take him at his word... even if his word contradicts his other words.
Finally, Tol's recent article says:
Mr Ward claims that "mistakes had been corrected" in the Fifth Assessment Report of Working Group II of the Intergovernmental Panel on Climate Change. In fact, we replaced the vague "may be beneficial" with the precise "17 out of 20 are negative", in line with the IPCC style which frowns on ambiguous wording and emphasizes the more likely outcomes.
This is incredibly misleading. Tol acts as though the IPCC only made one change to the report in response to Bob Ward's complaints. The reality is there were over a dozen changes to the data displayed and listed by the IPCC. Tol ignores them by pretending the only thing which matters are changes to the text of the IPCC report, but you can find a list of additional changes in the formal complaint I submitted to the IPCC (linked to earlier in this post).
This is not an exhaustive list of what is wrong with Tol's article, much less his published work. There is far more I could comment on. The reality is Tol's work is completely and utterly wrong, relying upon inappropriate statistical models to compare imcompatible data, data Tol consistently mangles and misrepresents.
I've discussed this in some detail before so I'm not going to rehash it here. If anyone wants information, I'd be happy to provide it.
March 17, 2015 10:20 Edit: It turns out the ruling I mentioned in this was not by the PCC. Details can be found in this comment.