Whom Can You Trust on Climate Change?

The furor over the stolen e-mail messages makes this a perfect time to focus on the value of peer review, writes Kevin B. Johnson.

December 8, 2009

The public and the media, for the most part, have failed to address a key point of the climate debate. Before attempting to educate anyone about how to interpret temperature and carbon dioxide data, there needs to be a better understanding of how scientific studies undergo quality control before being released to the general public. This is especially important in light of last week’s leak of controversial e-mails from prominent climate scientists.

The peer-review publication process is the mechanism the scientific community uses to prevent bad science, that is, to prevent data obtained with questionable methods or incorrect interpretations of data from being published. Solid science benefits from objective critical review, which can result in improved methods and more insightful interpretation of data. There is a body of literature, the peer-reviewed scientific journals, where the very best in scientific data and new discoveries gets published after being evaluated by independent experts working on similar or related problems in the same field.

In the initial stages of the peer-review process, an author submits a manuscript to a journal editor they believe is appropriate for their topic. The editor then typically selects two to four independent professionals to review the manuscript. Frequently, the editor will attempt to hand-pick reviewers who have published in the same field and, if possible, those who have reached alternative conclusions or developed contradictory hypotheses.

Reviewers are typically unpaid. More importantly, reviewers usually remain anonymous, and follow journal guidelines with respect to whether or not the manuscript should be accepted or rejected. For the most part, the peer-review process is geared in such a way that it is more likely that a good study will get rejected than that a bad study will get published.

Without the peer-review process, independent experts are unable to vet the information before it is foisted upon the public. This creates greater opportunity for money, politics, or mere opinions to taint the message. Hence, with respect to the climate change debate, for most people the issue should really boil down to whether or not one trusts the scientific review process. I don’t mean to insult people by suggesting they lack the capacity to understand climate data themselves. I’m an oceanographer and I still need to rely on the interpretation of more specialized experts for some climate change evidence.

A 2004 review of the scientific literature examined the 928 climate studies published in peer-reviewed journals from 1993-2003 to determine what evidence really exists for a human connection to climate change. This literature review, which itself was independently peer-reviewed before publication, found that 75 percent of the studies reported evidence of a human connection to climate change, 25 percent reported climate data with no bearing on the question, and, amazingly, not a single peer-reviewed study during that time period presented evidence refuting the idea of human-mediated climate change.

At times the media will attempt to raise concerns about the details of climate studies published in peer-reviewed journals. Given the rigorous and, at times, harsh nature of the review process, it is highly unlikely that these points were not considered by the expert reviewers who recommended a study for publication.

The e-mails that were stolen from a British university don’t seriously call the majority of climate change studies into question. The evidence and sources are far too diverse for one group of unprofessional scientists to be responsible for our view of climate change.

Obviously, the effect of these leaked e-mails is still very serious and reflects poorly on the scientists involved. It undermines the public trust in the unbiased ideal of the scientific process. Given that there is no better source for climate change information than the peer-reviewed literature, the real shame would be if the public grows to distrust the best information because of the apparent bias of a few scientists exposed in these e-mails.


Kevin B. Johnson is associate professor of oceanography at the Florida Institute of Technology.


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