An important study has just been published1 examining the level of consensus among scientists about climate change.
The issue at hand is this: What is the level of agreement in the scientific community about the reality of climate change and about the human role in climate change? The new paper, Quantifying the consensus on anthropogenic global warming in the scientific literature, address this question and the answer is very clear. The number of climate scientists who question the reality of global warming or the human role in global warming is vanishingly small.
This is not the first study to look at this question, but it is the most thorough effort. This should, however, be the last paper to report this kind of research because, really, we’re there; climate scientists are in very strong agreement about this issue and with this landmark study further demonstration of this fact is superfluous. (John Keegan discusses the merits of this paper relative to other similar efforts and closely examines issues such as sample size and bias here.)
How do we know there a consensus among scientists about human-caused climate change?
The research team, John Cook, Dana Nuccitelli, Sarah Green, Mark Richardson, Barbel Winkler, Rob Painting, Robert Way, Peter Jacobs and Andrew Skuce, examined 11,944 abstracts published in peer reviewed scientific journals from 1991–2011 that covered the topics “Global Climate Change” or “Global Warming.” They coded the abstracts to signify the apparent position on Anthropogenic Global Warming (AGW) and found that 66.4% expressed no position, 32.4% indicated acceptance of AGW, 0.7% rejected AGW and 0.3% expressed uncertainty as to the cause of warming.
Removing those papers that did not express an opinion, 97.1% “endorsed the consensus position that humans are causing global warming.”
The paper also looks at change over time in scientific consensus. The bottom line is that there isn’t much; consensus is not especially new. But there is a small trend, discussed by lead author John Cook in the video I provide below. Also, a look at the “reject AGW” papers shows that there are some patterns. Most are looking at large scale (known) change or cosmic sources of climate change, and they tend to be dated to the earlier part of the time range. Rabbet Run lists them here.
Consensus is often implied and not stated in peer reviewed papers
The researchers then invited the authors to rate the papers they had published. When this was done, the number of papers indicating no position on AGW dropped precipitously to 35.5%. In this rating system, 97.2% of papers endorse the consensus on AGW.
This is important for a couple of reasons. For one, it is an indication that the original coding was conservative, and did not involve assumptions about what the authors may have been thinking. It also shows something about how the scientific process works. If you look at any major scientific concept in the literature, you may find very little explicit endorsement of the overarching theoretical construct or model (like “Natural Selection” or “Germ Theory”) if that concept is fully established. Early writings on a particular major concept often refer to the concept itself and may cite early authors. For example one might see something like “Darwin’s concept of Natural Selection is being increasingly applied to understand the physical features of butterflies” with a reference to The Origin of Species. But after a while scientists stop mentioning the no-longer-novel overarching consensus and stop citing the seminal works. Climate science has moved into this state with respect to the human-caused warming of the earth because of the preponderance of evidence of AGW.
The Climate Change Consensus Gap
Depending on which poll you look at, and when the poll was taken, somewhat more than half of Americans either reject global warming as even being real, reject the human role, or simply don’t know about it. Given the scientific consensus, this is a little like saying that over half of Americans don’t accept Evolution as a valid set of theories and observations, despite the preponderance of evidence for that! (Hey, wait a minute…)
The point is, the gap between scientific consensus and public opinion is real, and very important. The consensus gap causes bad things to happen. For instance, it is quite reasonable for a government agency to fund or support public service announcements on drunk driving. There is a consensus that drunk driving causes deaths, injuries, and accidents. There is not a consensus gap in that area. But global warming also causes misery and mayhem. Shouldn’t there be public service announcements on saving energy and using alternative sources? The consensus gap means that there can’t be.
This of course has a direct effect on public policy, as noted by Naomi Oreskes writing for Science Magazine:
Policy-makers and the media, particularly in the United States, frequently assert that climate science is highly uncertain. Some have used this as an argument against adopting strong measures to reduce greenhouse gas emissions. For example, while discussing a major U.S. Environmental Protection Agency report on the risks of climate change, then-EPA administrator Christine Whitman argued, “As [the report] went through review, there was less consensus on the science and conclusions on climate change”. Some corporations whose revenues might be adversely affected by controls on carbon dioxide emissions have also alleged major uncertainties in the science (2). Such statements suggest that there might be substantive disagreement in the scientific community about the reality of anthropogenic climate change. This is not the case.
Leadership is when those with influence head directly for the truth, talk about the right thing to do, and help other people to do the right thing. Main Stream Media does not have that … that leadership thing. Main Stream Media does not look at the scientific consensus and then make judgements about what stories to cover and how to cover them on that basis. Rather, Main Stream Media looks at the range of public opinion and treats that as consensus (or lack of) and acts accordingly. Which, in turn, reinforces or even sometimes widens the gap.
This also causes problems in the liminal area of media commentary. Opinion editorials in major outlets like the Wall Street Journal often exploit the Consensus Gap, manufacturing uncertainty or attracting readers from among the misinformed part of the public, and again, reinforcing or even widening the gap and enhancing the level of public misunderstanding or just plain old ignorance. With respect to global warming, it is time for that to stop. As noted by Brendan DeMelle:
It does not get any clearer than this. It should finally put to rest the claims of climate deniers that there is a scientific debate about global warming. Of course, this bunch isn’t known for being reasonable or susceptible to facts. But maybe the mainstream media outlets that have given deniers a megaphone will finally stop.
Global Warming, Big Foot and the Loch Ness Monster
Editorials in Main Stream Media that exploit the consensus gap could be compared to editorials at the New York Times or in the Scientific American or your local newspaper that demand more attention be given to the plight of Big Foot or the Loch Ness Monster. The degree of scientific consensus that those creatures do not exist is about the same as the degree of consensus that AGW is real, though the public “belief” in crypto-critters is less than the public “belief” that AGW is not real. Why? Because Main Stream Media has not taken Big Foot or the Loch Ness Monster seriously in quite some time.
Ten years from now it will be interesting to look back and see how Main Stream Media’s editorial writers who today are sticking with “the jury is still out” on AGW managed their reputations as they looked more and more like they belonged at the National Enquirer rather than a respected news outlet.
John Cook, the study’s lead author, has also blogged about it here and also has a video summarizing the paper, which he discusses some of the earlier research as well:
This work was also covered by The Weather Channel.
1The embargo ended overnight last night, even though several climate science denialists failed to respect the embargo, thus, seemingly on purpose, violating a pretty standard ethical rule in academia.
The Consensus Project has a web site HERE and the twitter tag is #TCP
This is the paper:
Cook, J., Nuccitelli, D., Green, S., Richardson, M., Winkler, B., Painting, R., Way, R., Jacobs, P., & Skuce, A. (2013). Quantifying the consensus on anthropogenic global warming in the scientific literature Environmental Research Letters, 8 (2) DOI: 10.1088/1748–9326/8/2/024024