It's weird that this should still be necessary, but the recently launched Consensus Project presents the findings of a new survey which shows that out of more than 4,000 academic papers published in scientific journals, 97.1% agree that climate change is anthropogenic, i.e. caused by human activity.
The study (pdf) concludes that "the number of papers rejecting the consensus on AGW [anthropogenic global warming] is a vanishingly small proportion of the published research".
Wasn't this consensus already reached back in 2007, you might ask, when the Intergovernmental Panel on Climate Change (IPCC) and Al Gore received the Nobel Peace Prize? The year 'An Inconvenient Truth' came out?
Well, yes, in most parts of the world. But as the PBS documentary 'Climate of Doubt' details, US lobby groups actively and successfully waged a campaign of climate skepticism, to the point where last year only 42% of Americans believed climate change was human-caused. Hence the issue was largely off the political agenda in the 2012 US elections.
Crucially, this campaign did not have any message or alternative of its own beyond creating doubt and challenging the scientific consensus, thereby effectively extending fact-free politics to include fact-free science.
But it also cleverly exploited a journalistic weakness, or laziness, namely its practice of balanced reporting of contested issues, with an equal podium for differing points of view. The journalistic format nearly always reduces this balance to two views, for and against. In this case, a well-organized lobby circuit was only too happy to provide the 'against' voice whenever climate change was discussed, with the result that near-consensus often sounded more like a 50-50 divided issue.
By analogy, this would mean that every time Darwin's theory of evolution is discussed, intelligent design would have to be mentioned as an alternative view. Or even more ridiculously, every time our heliocentric universe is mentioned, a geocentric crackpot would need to get some airtime.
More fundamentally, such non-debates seem to be fueled by a misunderstanding of scientific language. Again the theory of evolution offers a good example, as this really isn't a 'theory' at all except in the philosophy of science meaning where every scientific fact is merely a theory waiting to be disproven. Excluding academic journals, journalists should recognize that this level of skepticism would produce very muddled and decidely unbalanced reporting.
In Darwin's case, it might clarify things to rename his theory into the law of evolution. And with the issue of human-caused climate change, well, it just needs some more repeating: "The debate is over."