When someone sells a view on climate change off the back of a quirk in the British weather, it’s best to ignore them. So let me be clear, today’s Deep End has nothing to do with last week’s summer sizzler. It’s not even about the record-breaking temperatures recorded across four continents last month.

Rather this is about Laudato Si’ – the Pope’s encyclical on environmental matters – and the political impact it’s had in America.

There was a time when anti-Catholicism was a powerful force on the American right (especially the extreme right). As recently as 1960, John F Kennedy had to assure voters that “I do not speak for my Church on public matters – and the Church does not speak for me.”

By the 1980s, there was a complete change of attitude. Pope John Paul II’s powerful witness against communism was applauded by American conservatives. Furthermore, the rise of social and cultural liberalism has drawn conservative Catholics and Protestants closer together than ever before.

However, Pope Francis – and Laudato Si’ in particular – is pushing the pendulum back the other way. The anti-environmentalists of the Republican Party are clearly discomfited.

In the Washington Post, Mike Gerson (who was George W. Bush’s speechwriter) advises his fellow conservatives to get over it:

“In American politics, the pope’s encyclical has not made legislative action on climate change inevitable, but it has made the issue unavoidable. The politician’s shrug — ‘I’m no scientist’ — is no longer acceptable. If climate change is a global threat, then addressing it, as the pope argues, is both a moral and public requirement.”

The trouble is that climate contrarianism has become an article of faith on the American right:

“Ten or 15 years ago, this issue was less divisive. But it got pulled into the polarization vortex. And now the two sides do not merely hold different policy views; they have different versions of reality. The camps not only advocate different solutions; they also inhabit different factual universes.

“Many conservative Republicans now deny the existence or danger of human-caused warming and routinely question the motives of scientists who speak up on the issue. For a conservative to stray from skepticism is regarded as ideological betrayal.”

It’s all part of the process in which the American right has constructed a counterpart to the political correctness of the left:

“This is the temptation of the ideologically intense on the left and right: Truth exists to serve the narrative rather than the narrative arising from truth. It is a malady easy to see in others and harder to diagnose in ourselves. But it is dangerous to democracy. Without a common factual basis, it is impossible to make incremental progress on public matters. All that remains are shouting matches and power plays.”

When one is stuck in a mental prison of this kind, the counter-arguments made by those previously identified as the enemy only serve to reinforce the original prejudice. The Pope, however, is someone previously identified as a friend (or at least as an enemy of one’s enemy). For such a person to insist that climate change is not only real, but a matter on which we are morally obliged to act, is quite a challenge.

Some right-wingers have reacted by labelling Francis a Marxist. Others hope the whole thing just goes away.

In doing so they disregard the moral authority  of the Church – which, of course, they are entitled to do as free-born Americans. What they can’t consistently do, however, is disregard conservatism itself – which is all about facing up to inconvenient truths.

As Gerson puts it: “conservatives can choose their policy reaction but not their own reality.”