Originally posted at Skeptical Science
One of the perennial Skeptical Science top ten climate myths is “There is no consensus” (currently at number 4 in popularity). Consensus means the elements of knowledge that research scientists tend not to discuss or actively investigate any more. Consensus is the stuff that fills textbooks and is the established knowledge that teachers try to cram into high school and undergraduate students’ heads. It doesn’t mean an impregnable bastion of knowledge—there are many well-known examples of consensus-changing revolutions in the history of science—and even school textbooks have to get updated every now and then.
Consensus doesn’t mean unanimity, either. There is always a minority of gadfly scientists who decide to take on the consensus: scientists who challenge the biotic origin of oil or medical researchers who doubt HIV as a cause of AIDS. In such cases, the contrarian scientists don’t typically deny the existence of the consensus; they just think that the content of it is wrong.
Nor does consensus mean that everybody is happy with every single element that others believe to be settled. Consensus in any field has a hard core but fuzzy edges.
There have been a few studies that have attempted to measure the degree of scientific consensus on climate change. Naomi Oreskes in 2004; Doran and Zimmerman in 2009; Anderegg et al in 2010; and the Vision Prize in 2012. All found evidence for a very strong consensus among climate scientists for the idea that recent climate change can mostly be attributed to human activities (see the recently updated rebuttal written by Dana Nuccitelli for details). Most of the world’s scientific academies have made explicit affirmations of the consensus on climate, along with numerous scientific associations. The IPCC reports are a major effort to define the extent of general agreement and to identify the areas of remaininguncertainty.
Yet, contrarians persistently deny that a consensus exists among climate scientists. In particular, they maintain that climate scientists are deeply divided even over the high-level conclusions to be found, for example, in the Summary for Policymakers sections of the IPCC reports. The consensus-denial tactics involve minor criticisms of sample size and methodology of the published consensus studies, hyping the work of the few dissenters and citing surveys of non-specialist scientists and engineers. None of this criticism makes a dent on the massive and obvious evidence for consensus.
For example, see a recent article debunked by the blog Watching the Deniers, where somebody had cherry-picked skeptical quotes from a few scientists who responded to the Doran and Zimmerman study (Eos, January 20, 2009). This only reveals that some people confuse consensus with unanimity.
A recent Wall Street Journal op-ed by Roger Cohen, William Happer and Richard Lindzen was headlined ‘Climate Consensus’ Data Need a More Careful Look. They dismiss the consensus with the straw-man argument that consensus is simply the repetition of a single fib, while making the false claim that:
It is increasingly clear that doubling CO2 is unlikely to increase global temperature more than about one degree Celsius.
As if there was an emerging body of literature or multiple lines of evidence pointing in that direction: their claim seems to be based on a single publication, Lindzen and Choi 2011. As Dana Nuccitelli wrote here in his article on that paper:
Since the body of research using multiple different approaches and lines of evidence is remarkably consistent in finding an equilibrium climate sensitivity of between 2 and 4.5°C for doubled CO2 (whereas a ‘low’ sensitivity would be well below 1.5°C), climate contrarians reject the body of evidence by (falsely) claiming it is based on unreliable models, and attempt to replace it with this single study by Lindzen and Choi under the assertion that it is superior because is observationally-based.
At least Cohen, Happer and Lindzen do not deny the existence of a scientific consensus, even if they disagree with its content. That’s more than can be said for some commentators, as we shall see.
Larry Bell in Forbes
A recent article by Larry Bell in Forbes went over the now-familiar ground of denying the consensus on climate change. He criticized the Doran and Zimmerman study for having too small a sample size and for asking vague questions (although, as I will discuss below, he is forgiving of similar questions and sample sizes of a study done by the Association of Professional Engineers, Geologists and Geophysicists of Alberta (APEGGA)). He cited the Oregon Petition, debunked here, while ignoring the work of Oreskes (2004) and Anderegg et al (2010). He cited the Polish Academy of Sciences PAN Committee of Geological Sciences, while ignoring the position of the General Assembly of the Polish Academy of Sciences, which endorses the IPCC conclusions, along with many other national science academies.
Most of Bell’s arguments have been debunked before and there’s little point in discussing them here again in detail. However, I have some personal familiarity with APEGGA, having been a member of this organization for many years, so I will look at that case of a supposedly dissenting scientific organisation in more detail.
APEGGA and climate science
APEGGA (now APEGA) is a professional body that regulates the practice of engineering and geoscience (previously geology and geophysics) in the Canadian province of Alberta. Approximately 90% of the professional members are engineers and 10% geoscientists. By provincial law, anybody who works as an engineer or geoscientist in Alberta must be a member of the association, including academics. As might be expected in a province that employs thousands to exploit the largest deposit of bitumen on the planet, there is widespread “skepticism” of anthropogenic climate change among the membership. These views frequently manifest themselves in the organization’s newsletter, sometimes associated with accusations of fraud directed at climate scientists, along with pseudo-science on climate change and, sometimes, young-Earth geochronology. I protested about this in a letter published in the June 2010 edition of the association’s news magazine (page eight).
Larry Bell wrote:
A March 2008 canvas of 51,000 Canadian scientists with the Association of Professional Engineers, Geologists and Geophysics of Alberta (APEGGA) found that although 99% of 1,077 replies believe climate is changing, 68% disagreed with the statement that “…the debate on the scientific causes of recent climate changeis settled.”
The survey report is here. Note that just a self-selected 2% of the membership responded to the survey, only 15% (about 160) of whom were professional geoscientists. Many of these engineers and geoscientists would likely be oil industry employees with little professional knowledge or expertise in climate science. The survey reported:
There is even less agreement as to the cause: 27.4% believe it is caused by primarily natural factors (natural variation, volcanoes, sunspots, lithospheremotions, etc.), 25.7% believe it is caused by primarily human factors (burning fossil fuels, changing land use, enhanced water evaporation due to irrigation), and 45.2% believe that climate change is caused by both human and natural factors.
Bell’s conclusion that:
Only 26% of them attributed global warming to “human activity like burning fossil fuels.”
is not correct; in fact, 71% accepted at least some degree of a human role by selecting either “primarily human” (25.7%) or “both human and natural” as causing global warming. The problem here is that even mainstream climate scientist would have been able to vote for “both human and natural”. Nobody denies that solar variations and large volcanic eruptions have played a measurable role in modern climate change. The question is poorly worded, a problem Bell skips over in this case, perhaps because he approves of the result.
The main problem, however, is in citing the opinions of a small, self-selected group, predominantly of engineers, on a subject in which they have little professional expertise. We should heed this survey to the extent that Alberta’s engineers might be expected to pay attention in the unlikely event that atmospheric scientists try to tell them how to build pipelines.
The hallmark of a professional engineer or scientist is in knowing his or her limits of competence. When APEGGA’s then executive director, Neil Windsor, quoted in the Forbes article, declared as a result of the 2008 survey, that: “There is no clear consensus of scientists that we know of”; we should perhaps read it as a confession of ignorance rather than the comment of an informed expert.
Why is the climate science consensus important?
The public understanding of science is not, alas, very good. When it comes to understanding basic science, even Harvard graduates, for example, may have difficulty explaining why the Earth has seasons. In a recent study by Daniel Kahan, “scientific literacy” was determined by asking rather simple questions, in this case, only 32% knew that the Earth goes around the Sun one time per year. See also the study Americans’ Knowledge of Climate Change (pdf 8MB).
Climate science can be very difficult to understand, with many people, even experts, occasionally struggling to explain a consensus concept such as an anthropogenically cooling stratosphere. Nobody can grasp it all; we all have to accept parts of the subject largely on trust. Even though consensus doesn’t logically entail certainty, it’s a good enough indicator for most of us to accept the scientific consensus as the most reliable knowledge available.
On the other hand, if somebody rejects the consensus view, they are claiming that they can see flaws and weaknesses where the majority of experts sees none. Convincing others (and perhaps themselves, first) that there’s actually no scientific consensus may help deflect charges that their opinions are merely fringe views.
The reality, of course, is that there is indeed a very well-documented consensus on climate change. The public is misinformed of this fact through the deliberate dissemination of manufactured doubt by fake skeptics, which is amplified by false balance reporting in the media (Boykoff and Boykoff, 2004). For most non-scientists, their decision to accept or reject the scientific consensus on climate change is inseparable from their awareness of the existence of the consensus itself. For this, the general public is largely at the mercy of the media.
A survey of 1010 American adults conducted in 2011 by Yale and George Mason Universities, revealed (Question 31) that only 15% of those polled believed that 81% or more of “climatescientists think that global warming is caused mostly by human activities”. Although it may be asking too much of today’s financially stressed print and broadcast media to report on the complex details of climate science, surely reporters could at least write accurate stories on the state of the scientific consensus.
Nobody has to take the media’s word for it, though. Anyone can spend a day at a big scientific conference, like the AGU Fall Meeting, listen to some talks, question scientists in the hallway and eavesdrop at discussions in the poster sessions. The visitor will see scientists engaged in heated discussions about almost everything. What they won’t observe are scientists wasting time debating any of the most used Skeptical Science climate myths.
Taking timely action to avert the worst consequences of climate change requires good public policy. Policy change requires widespread public support. That support will not be sufficient until the broad scientific consensus on climate change is recognized as a fact.