It makes no more sense to be certain that the globe is definitely not warming than to be certain that it definitely is. It makes no more sense to be certain that if the globe is warming it is not due to carbon emissions than to be certain that it definitely is. It makes no more sense to be certain that there will not be dire consequences if the globe is warming than to be certain that there will be.

All public policy deals with uncertainty, which means it is well for policymakers and their critics always to show a bit of humility. That is what is in short supply in the “science is certain” crowd. No chance, not even the slightest that they might be wrong. Let temperatures fail to rise and it is a temporary glitch. Or due to mis-measurement of those temperatures. Or to the need to make adjustments in the elaborate models on which the “certain science” has been based. Anyone who disagrees is a “denier”, a word until now reserved for mullahs who deny the existence of the Holocaust.

The pundits who are certain, really certain, that all of those scientists are wrong are no better, although they have a reasonable excuse for counter-certainty: the rudeness with which doubters are treated – barred from academic journals and positions and, most recently, from meetings with Pope Francis while he was formulating his latest attack on carbon emissions and capitalism. They accuse those who believe in the warming-from-emissions-caused-by-human-activity trinity of seeking to expand the power of government on the back of bogus science. Some such there undoubtedly are. But surely not all. They also accuse them of seeking a means of raising taxes, by enacting a carbon tax.

And that is where they are wrong. Those taxes are already being levied – by the producers of the emissions that may, only may, be creating costs for society as whole. The costs of emissions, not fully reflected in the price of fossil fuels, are being borne by a society that did not vote to impose such a tax on itself. It is a form of taxation without representation, something that history suggests Americans find unacceptable. Given the need to offset rising inequality and give growth a boost, reform of the tax structure is essential. A tax that takes the already-existing costs of emissions and imposes them on the creators of the emissions rather than on innocent bystanders seems a modest step forward, perhaps on behalf of the environment, certainly on behalf of a more equitable and growth-oriented tax structure.