One of the most frequently debated issues in the climate change debate is the idea of “scientific consensus.” This is not the first time political forces have sought to use this approach to bolster support for their views, nor is it likely to be the last. In the case of climate change, I suspect that there is often an intentional attempt to confuse the debate.
I find very few people who, upon looking at the data, deny that the climate has changed over the past century or more. In fact, what they are saying is that the climate is always changing. The central questions revolve around how the climate changes and what are its likely consequences. For instance:
How much of the change is a result of natural changes like increases in the sun's radiation and how much is the result of human activity?
Are projected temperature levels outside the norms of historic fluctuations?
What is the likely impact of more releases of greenhouse gasses? Will temperatures rise logarithmically higher because of each amount of the gases added? Will it be a proportional increase? Is it possible that the gasses have had a contributory affect up to a certain concentration but beyond that additional gasses have little impact?
Will changes in human activity reduce the gasses and what impact will that have? What is the cost and benefit of such actions?
The most alarming models that get the most media coverage claim a) unprecedented global warming b) precipitated by human activities c) causing cataclysmic problems. Challenges to any of these three, earns the challenger the label of climate change, or global warming, “denier.” It is a misrepresentation. The challenger is not denying change or warming. The challenger is challenging the model used to interpret climatic change and their predicted outcomes. More about this misrepresentation in my next post but first let us take a closer look at the very of idea of scientific consensus.
Al Gore released a movie last year called “The Inconvenient Truth.” Gore referenced a study in Science Magazine that reviewed 928 abstracts of articles about global climate change and found that none of them disputed human caused global warming. You can find that article by Naomi Oreskes, published in 2004, by clicking here. Orsekes claims that 75% of the articles contain explicit endorsement of the consensus position, evaluation of impacts, or offer mitigation proposals. About 25% deal with paleoclimatology, methods, or other issues where no position is indicated. While this study looked at peer-reviewed articles, Oreskes’ article itself was not peer-reviewed. This article, via Al Gore, is the most frequently cited source concerning unanimous consensus.
Within a month after the publication of the article, Dr. Barry Peiser of John Moores University sought to replicate Oreskes' study. Doing a search on the phrase “climate change” in abstracts for the same time period using the same database, Peiser found more than 12,000 hits. Peiser contacted Oreskes and she explained that she had searched on the phrase “global climate change.” So Peiser again tried to replicate the search. He got 1,247 hits, or one third more than Oreskes. Only 1,117 of these had full abstracts. Questioning Oreskes findings, Peiser conducted his own study. Using eight categories, here is what he found:
- 13 (1%) Explicitly endorse the 'consensus view'
- 322 (29%) Implicitly accept the 'consensus view' but mainly focus on impact assessments of envisaged global climate change.
- 89 (8%) Focus on "mitigation.”
- 67 (6%) Mainly focus on methodological questions.
- 87 (8%) Deal exclusively with paleo-climatological research unrelated to recent climate change.
- 34 (3%) Reject or doubt the view that human activities are the main drivers of the "the observed warming over the last 50 years.
- 44 (4%) Focus on natural factors of global climate change.
- 470 (42%) Abstracts include the keywords "global climate change" but do not include any direct or indirect link or reference to human activities, CO2 or greenhouse gas emissions, let alone anthropogenic forcing of recent climate change.
Using Oreskes criteria, Pesier found only 424 articles (38%) that contained explicit endorsement of the consensus position, evaluation of impacts, or offered mitigation proposals. This is not insignificant but neither is it unanimous consensus.
Another scientist named Denis Bray sent out a survey in 2003, to climatologists worldwide asking “To what extent do you agree or disagree that climate change is mostly the result of anthropogenic causes?” Respondents could select seven options ranging from “1 = strongly agree” to “7 = strongly disagree.” He got 530 responses. Here are the results:
- strongly agree 50 (9.4% of valid responses)
- 134 (25.3% of valid responses)
- 112 (21.1% of valid responses)
- 75 (14.2% of valid responses)
- 45 (8.5% of valid responses)
- 60 (10.8% valid responses)
- strongly disagree 54 (9.7% of valid responses)
This indicates a slight majority of respondents believe anthropogenic warming is occurring but once again, it is hardly an overwhelming consensus.
Having said all of this, the reality is that science is not done by consensus!
George H. Taylor, past president of the American Association of State Climatologists:
But even if there actually were a consensus on this issue, it may very well be wrong. I often think about the lives of three scientists who found themselves by themselves, on the "wrong side of consensus." There have been many in the history of science, but I singled out Alfred Wegener (Continental Drift), Gilbert Walker (El Niño), and J. Harlan Bretz (Missoula Floods). None is well-known now among members of the public, and all of them were ridiculed, rejected, and marginalized by the "consensus" scientists -- and each of the three was later proven to be correct, and the consensus wrong. As a well-known writer once said, "if it's consensus, it isn't science -- and if it's science, it isn't consensus." (A Consensus About Consensus)
Science is not conducted by consensus. Science is accomplished by assembling a collection of theories into a paradigm. Aspects of that paradigm are then tested for validity. As more aspects of the paradigm fail to be falsified, the paradigm takes on greater validity as a paradigm to explain the issue under investigation. Falsifications lead to revisions and enough falsifications usually lead to a new paradigm.
For science to function in a healthy manner, room has to be made for dissenters to publish research that challenges conventional understanding without fear of retribution. I am a theistic evolutionist who questions whether intelligent design can be labeled science. However, I think many in the science community may have erred in their attempts to shut out ID advocates from publications rather than letting them publish there findings and have them scrutinized by scientists.
The problem with climate change science is that, as yet, there is no one model of climate change, even among those who adamantly insist that the change is anthropogenic. What models do exist are computer simulations that are collections of the programmer’s assumptions combined with real world observable data. For these models to correctly work they most correctly model five extremely complex and interdependent systems: a) atmosphere, b) oceans, c) ice - covered regions (cryosphere), d) land masses (lithosphere), and e) plant and animal life (biosphere). When applying present model assumptions about warming to the world as it existed 100 years ago they overestimate future temperature change by double or more.
Consequently, when we talk about consensus on something like climate change we are not talking about something akin to scientific principles like gravity or the laws of thermodynamics. We are venturing more into the area of educated guesses. We have enough data to suggest we might have a problem but insufficient models to determine the precise nature of the problem (if there is a problem) and what might be done. Going back to Giddens in the first post, what we have is uncertainty about a potential and serious threat.