Tag Archives: agw denialism

Scientific Consensus On Climate Change

A new paper examines what is behind the ~2% of climate change related peer reviewed research that run contrary to widely accepted scientific consensus on climate change to see why those papers are wrong.

There is a scientific consensus that increasing greenhouse gas concentration in the atmosphere causes surface warming, and that CO2 is a major greenhouse gas. This consensus is based on physics. We don’t need to observe the effects of human greenhouse gas pollution to know this. There is consensus that human burning of fossil fuel causes an increase in CO2 in the atmosphere. We don’t need to observe this to know it, because we know how combustion works. But it is relatively simple to measure, and it has been measured, and it is true. There is consensus that the planet’s surface has warmed. This is expected from the physics and the fact that we are increasing atmospheric CO2, but it is also relatively easy to measure, it is measured, and it is true. There are varying levels of understanding the effects of this process, and varying degrees to which the effects of surface warming are thought to cause specific effects. One could probably characterize the scientific consensus as a widespread understanding that surface warming has had and will have a range of effects, with many of those effects being changes in weather patterns or regional climatology (how warm/cool/dry/wet a region generally is across he seasons) arising from a combination of “natural variability” (what would happen without greenhouse gas pollution) and anthropogenic global warming.

It is interesting, then, to see the results of various studies of scientific consensus related to climate change. Two kinds of studies have been done. One asks scientists what they think, the other reviews the scientific literature to see what the peer reviewed papers that address climate change say. In both cases we see a number between 90 (or, really, 95) and 100 percent agreement on the stuff in the paragraph above. It is not surprising that the vast majority of scientists, and the vast majority of research papers, have very similar things to say about climate change. This is not new science, and while climate is very complex, the basics of anthropogenic global warming are well understood. The results of empirical research closely match expectations derived from the physics. It all hangs together pretty well.

What is surprising is to see that 3-6% or so disagreement. Who are those scientists, why do they disagree, what do those papers say?

I would assume that since consensus research takes time, and often looks at several years worth of papers, that some of that non-consensus reflects older thinking and older research. Also, there are climate contrarians, including some scientists, who oppose the consensus for reasons not based on the science. That sort of denial presumably comes from the simple fact that some corporations or wealthy individuals will see reduced profits as we make the inevitable shift away from fossil fuels. So some of that non-consensus may be bought and paid for self interested maneuvering.

Rasmus Benestad, Dana Nuccitelli, Stephan Lewandowsky, Katherine Hayhoe, Hans Olav Hygen, Rob van Dorland, and John Cook, in “Learning from mistakes in climate research” (Theoretical and Applied Climatology) looks at the non-consensus peer reviewed literature.

The paper is here, and author Dana Nuccitelli has a writeup on the paper here. From the abstract:

Among papers stating a position on anthropogenic global warming (AGW), 97 % endorse AGW. What is happening with the 2 % of papers that reject AGW? We examine a selection of papers rejecting AGW. An analytical tool has been developed to replicate and test the results and methods used in these studies; our replication reveals a number of methodological flaws, and a pattern of common mistakes emerges that is not visible when looking at single isolated cases. Thus, real-life scientific disputes in some cases can be resolved, and we can learn from mistakes. A common denominator seems to be missing contextual information or ignoring information that does not fit the conclusions, be it other relevant work or related geophysical data. In many cases, shortcomings are due to insufficient model evaluation, leading to results that are not universally valid but rather are an artifact of a particular experimental setup. Other typical weaknesses include false dichotomies, inappropriate statistical methods, or basing conclusions on misconceived or incomplete physics. We also argue that science is never settled and that both mainstream and contrarian papers must be subject to sustained scrutiny. The merit of replication is highlighted and we discuss how the quality of the scientific literature may benefit from

The researchers found that cherry picking was the most common explanation for the non-consensus papers contrary results. In other words, it is not the case that a small number of paper simply found the physics, or some other aspect of, global warming to be different than other researchers found, or that they were looking at a part of the system that acts differently. Rather, these papers were wrong, and for a specific reason.

We found that many contrarian research papers omitted important contextual information or ignored key data that did not fit the research conclusions. For example, in the discussion of a 2011 paper by Humlum et al. in our supplementary material, we note,

The core of the analysis carried out by [Humlum et al.] involved wavelet-based curve-fitting, with a vague idea that the moon and solar cycles somehow can affect the Earth’s climate. The most severe problem with the paper, however, was that it had discarded a large fraction of data for the Holocene which did not fit their claims.

The authors attempted a replication of that particular research, and found that the model they used only worked for part of the underlying data. The data that were ignored by Humlum et al contradicted their findings.

Another problem identified by Benestad et al is the lack of a consistent sensible alternative explanation for their alleged findings. “…there is no cohesive, consistent alternative theory to human-caused global warming. Some blame global warming on the sun, others on orbital cycles of other planets, others on ocean cycles, and so on. There is a 97% expert consensus on a cohesive theory that’s overwhelmingly supported by the scientific evidence, but the 2–3% of papers that reject that consensus are all over the map, even contradicting each other.”

Go read Dana Nuccitelli’s post in The Guardian for more discussion of this interesting new paper. Also, the lead author has a post on this paper at RealClimate.

The Consensus on Climate Change

Sadly, a large percentage of Americans are under the impression that climate scientists do not agree on the reality of anthropogenic global warming (AGW). A lot of people are simply wrong about this. They think that there is a great deal of controversy among the scientists who study the Earth’s climate. But there isn’t. One way we know this is from a study done by John Cook, Dana Nuccitelli, Sarah A Green, Mark Richardson, Bärbel Winkler, Rob Painting, Robert Way, Peter Jacobs, and Andrew Skuce, called “Quantifying the consensus on anthropogenic global warming in the scientific literature

In that study, the authors analyzed “the evolution of the scientific consensus on anthropogenic global warming (AGW) in the peer-reviewed scientific literature, examining 11,944 climate abstracts from 1991–2011 matching the topics ‘global climate change’ or ‘global warming’.” They learned that “66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming.” Among the papers that expressed a scientific position on the topic, “97.1% endorsed the consensus position that humans are causing global warming.”

The study was actually a bit conservative, as in order to be counted as part of that ~3% not supporting the consensus position on AGW a paper did not really have to be fully against the idea. Also, since the study was done, the consensus has increased. I asked study author Dana Nuccitelli about more recent changes in consensus, and he told me, “The consensus is growing over time, and reached 98% in 2011 (the last year included in our survey). So by now the minimizers/deniers are probably in the 1-2% range in the peer-reviewed literature (contrary to the ‘crumbling consensus’ claims).”

The other day I was giving talks at a local high school, and between classes, found myself chatting with a science teacher who had just completed a module on climate change and AGW. She asked me, “Isn’t there now research that shows that the consensus isn’t really as high as previously thought? Or is that bogus? Sounds bogus to me.”

Yes. Bogus.

I’m not sure what research the teacher was referring to (it was just something she had heard about) but there is a paper just published in “Energy Policy” by economist Richard Tol, who as far as I can tell has been a naysayer of climate science for some time now. Tol’s abstract says:

A claim has been that 97% of the scientific literature endorses anthropogenic climate change… This claim, frequently repeated in debates about climate policy, does not stand. A trend in composition is mistaken for a trend in endorsement. Reported results are inconsistent and biased. The sample is not representative and contains many irrelevant papers. Overall, data quality is low. Cook’s validation test shows that the data are invalid. Data disclosure is incomplete so that key results cannot be reproduced or tested.

Nuccitelli has responded to Tol’s paper, in a post at Skeptical Science called “Richard Tol accidentally confirms the 97% global warming consensus.”

Concern Tol-ing

Tol is practicing a special kind of science denialism here, sometimes called “seeding doubt” or as I prefer it, “casting seeds of doubt on infertile ground.” In other contexts this is called “concern trolling” or the “You’re not helping” gambit. The first of two paragraphs of the Conclusion section of Tol’s paper reads (emphasis added),

The conclusions of Cook et al. are thus unfounded. There is no doubt in my mind that the literature on climate change overwhelmingly supports the hypothesis that climate change is caused by humans. I have very little reason to doubt that the consensus is indeed correct. Cook et al., however, failed to demonstrate this. Instead, they gave further cause to those who believe that climate researchers are secretive (as data were held back) and incompetent (as the analysis is flawed).

Let’s get straight that Cook et al is not flawed, despite Tol’s complaints.

Tol’s main complaint is in the coding of the abstracts. He claims that it is imperfect. Well, duh. This is, essentially, social science research, and coding of text is imperfect. Tol makes the claim that the imperfections, if corrected, might bring the consensus down to a dismal 91%. I’m pretty sure he’s wrong about that, but if he is right, we are not impressed.

Tol’s key point is that the papers that are coded as not making a claim include some that do. He then incorrectly calculates how many of of those, if coded “correctly” there would be, and using this, downgrades the consensus to 91%

Nuccitelli explains in detail, in his post, how Tol’s re-analysis is badly done (see the amazing graphic at the top of this post) (go read it) and notes:

In reality, as our response to Tol’s critique (accepted by Energy Policy but not yet published) shows, there simply aren’t very many peer-reviewed papers that minimize or reject human-caused global warming. Most of the papers that were reconciled ‘towards stronger rejection’ went from explicit to implicit endorsement, or from implicit endorsement to no position. For abstracts initially rated as ‘no position,’ 98% of the changes were to endorsement categories; only 2% were changed to rejections.

Nuccitelli also notes that a separate study indicates that Tol’s method is flawed in the sense that no matter what data are used, the consensus will be decreased as an artifact of the methodology. Nuccitelli notes “…by making this mistake, Tol effectively conjured approximately 300 papers rejecting or minimizing human-caused global warming out of thin air, with no evidence that those papers exist in reality. As a result, his consensus estimate falls apart under cursory examination.”

Amazingly, when the Consensus research team fixed Tol’s methodology but applied the same question about coding papers in the no-position category, and re-calculated the percent consensus, it went up by 0.1%. Also, as Nuccitelli points out the Cook et al paper is not alone, and there have been a number of other studies that show essentially the same level of consensus among papers and/or scientists.

So, the consensus is real and isn’t going away. As is also the case with Anthropogenic Global Warming.

The Heartland Science Denial Documents and the Future of the Planet

The best available evidence now suggests that the most damning of the “Heartland Documents” — the strategy memo which explicitly states that Heartland’s strategy is to interfere with good science education in order to advance their political agenda — is legitimate. The legitimacy of the document was being questioned because it was physically and stylistically different from the other documents with which it was released. We now know that the strategy memo was sent to climate scientist Peter Gleick and that Peter then took steps to acquire corraborating documents from Heartland (see “The Origin of the Heartland Documents.”) The “one of these things is not like the others” defense is now obviated.
Continue reading The Heartland Science Denial Documents and the Future of the Planet

CloudGate: Denialism Gets Dirty, Reputations Are At Stake

There has been a major dust-up in the climate denialist world. A study published in late July made false claims and was methodologically flawed, but still managed to get published in a peer reviewed journal. The Editor-in-Chief of that journal has resigned to symbolically take responsibility for the journal’s egregious error of publishing what is essentially a fake scientific paper, and to “protest against how the authors [and others] have much exaggerated the paper’s conclusions” taking to task the University of Alabama’s press office, Forbes, Fox News and others.

Let me break it down for you
Continue reading CloudGate: Denialism Gets Dirty, Reputations Are At Stake