Copenhagen has come and gone, but the climate change naysayers are still very much with us. And they are indisputably right about one thing: the scientific consensus can be wrong.
Scientists and their predecessors, the natural philosophers, have been in error in the past on many things, from planetary orbits to the origins of humankind. Scholars with impressive-sounding qualifications argued that the Sun revolved around the Earth and that God created the natural world in all its variety in one astonishing burst of creativity. They were wrong then. So couldn't those massed ranks of doctorate-laden climate scientists, oceanographers and physicists be wrong now about mankind's role in warming the climate?
Yet just because the consensus has, on occasion, been wrong it doesn't follow that the settled view of the scientific community is always in error. This is where the critics of the majority scientific view on global warming run into trouble. The minority of scientists who argue that the theory of anthropogenic climate change is a fiction, whatever other achievements they might have to their name, have failed to undermine the consensus view. If these oppositionist scientists were right, they should surely be sweeping all before them, just as Darwin exploded conventional wisdom about the origin of species, and Copernicus and Galileo revolutionised established views about the nature of the cosmos.
But that inexorable victory for the position of the climate oppositionists isn't what we're seeing. The scientific consensus that global warming is the result of human activity has, in fact, significantly hardened in recent years, despite the efforts of dissenting scientists such as Ian Plimer and Patrick Michaels.
Rather than admit that the traditional process by which scientific truth is revealed has failed to vindicate them, these scientists and their often eloquent lay supporters fall back on the allegation that there is a conspiracy in the scientific establishment to silence them, a plot to marginalise those who will not conform to the orthodoxy. Climate science, we are told, has become like a religion, where heretics are ruthlessly suppressed, just as the Catholic Church suppressed Galileo.
Does this sound plausible to you? No heretics have been put under house arrest lately. Indeed, the theories of the oppositionists have been addressed in great detail. The arguments and counter-arguments are available to anyone who cares to look. Is it not more likely that the case of those who do not agree with the consensus has been weighed and simply found wanting?
Aha, say the diehards, what about those leaked emails from the Climatic Research Unit of the University of East Anglia? Do they not show intent from some prominent climate change scientists to suppress contrary research? The emails certainly don't paint the unit in a flattering light. And in so far as they show attempts to frustrate Freedom of Information requests, they are shameful. But the naysayers need to show that these scientists – and thousands of others – have falsified their data before they can claim victory. So far they've been unable to do that.
Ad hominem attacks are no substitute. The naysayers say that scientists have an incentive to scare policymakers because that's what delivers the research grants. But there's another powerful incentive in the world of science: the prestige to be had from overturning an orthodoxy. Or are we to believe that only the oppositionists possess such sceptical instincts?
In the end, this is not an argument about science, but logic. Those of us who are not scientific specialists are no more able to talk authoritatively about the physics of climate change than we are able to explain how vaccination works, or how the HIV virus results in Aids. But we (generally) take our jabs and practise safe sex. Scientific consensus matters. Not because the consensus is always right, but because it is the only guide to rational action and policymaking.
Climate change naysayers might yet come up with evidence that disproves the theory of man-made climate change. That would be a revolutionary moment. And the world would surely thank them for their efforts. But it hasn't happened yet. In the meantime it falls to the open-minded layperson and the responsible politician to check that the debate has been free, to ensure that no inconvenient research has been suppressed, and to act in response to the consensus view.
The climate naysayers would have us treat science like an a la carte menu, where we pick out what suits us and dismiss what doesn't. Sorry, but speaking as a non-scientist, that doesn't sound very appetising.