When people hold strongly conflicting values, interests, and beliefs, there is not much that science can do to compel action. Indeed, more research and more facts often make a conflict worse by providing support to competing sides in the debate, and by distracting decision-makers and the public from the underlying, political disagreement. In such cases each side will claim to have the scientific high ground.
Writing in the New York Times last week, Al Gore made exactly this point about climate change by noting that "the science has become clearer and clearer." Yes, there is a robust scientific consensus that human activity is causing the atmosphere to warm up. But so what? Decision-makers need to know how climate change will affect specific political jurisdictions, and, more importantly, what types of interventions will make a difference, over what time scales, at what costs, and to whose benefit—and whose detriment.
When it comes to questions like these, political beliefs can map nicely onto different ways of selecting, assembling, and interpreting the science. If you believe that government should intervene in markets to incentivize rapid reduction of greenhouse gas emissions, you can justify your preference with data, theories, and models that predict increases in extreme weather events such as hurricanes, droughts, and floods. And if you believe, as do many conservatives, that government intervention in markets and in social arrangements should be kept to a minimum, you can find factual support for your views in the long-term unpredictability of regional climate behavior, the significant economic and social costs associated with shifting to more expensive energy sources, and the historical failure of government efforts to steer large-scale social and economic change.
Politics isn't about maximizing rationality, it's about finding compromises that enough people can live with to allow society to take steps in the right direction. Contrary to all our modern instincts, then, political progress on climate change requires not more scientific input into politics, but less. Value disputes that are hidden behind the scientific claims and counterclaims need to be flushed out and brought into the sunlight of democratic deliberation. Until that happens, the political system will remain in gridlock, and everyone will be convinced that they are on the side of truth.