Winston Churchill called it the enemy within. Leonardo da Vinci noted that: “As every divided kingdom falls, so every mind divided between many studies confounds and saps itself.” If there is one word that sums up current attitudes to the climate problem and society’s response to it, then it is ‘divided’. And that describes just the attitudes of those who agree that there is a serious problem to deal with.

Those who do not accept this reality — for whatever reasons — must have been rubbing their hands this week as arguments raged among their opponents. There is a new term in town — ‘ecopragmatist’. It can be used both as a compliment and an insult.

The lightning rod for the latest storm was a fairly benign talk given in New York this month by New York Times environment writer Andrew Revkin on the difficulty of applying numerical targets and goals, on carbon emissions say, to real-world behaviour. It might have gone largely unnoticed, except that Revkin included in the talk’s title the idea of a ‘good’ Anthropocene — the informal name for the period, beginning at the Industrial Revolution, in which humans have substantially altered Earth’s ecosystems. To place the words ‘good’ and ‘Anthropocene’ together, even with the former in quotation marks, is heresy to some. In Scientific American on 19 June, the Australian ethicist Clive Hamilton delivered a broadside against those who argue that human ingenuity, not behaviour change, is the best response to rising carbon emissions. “Such unbounded optimism is dangerous, wishful thinking,” he wrote, because it plays into the hands of those who would protect the status quo, whatever the environmental consequences.

Perhaps there is more to this than division along the optimism–pessimism axis; whether someone is the sort of person who sees an atmosphere half-full or half-empty of carbon dioxide. As is made clear in a useful report published this week by the UCL Policy Commission on Communicating Climate Science in London, public discussion of climate change has deeper psychological roots. It is “as much about what sort of world we wish to live in, and hence about ethics and values, as it is about material risks to human wellbeing”.

The report is, for want of a better word, ecopragmatic. It acknowledges an awkward truth: if climate scientists are failing to get their message across to the wider public, then it could be the message that is the problem, not the public. The authors of the report acknowledge that some of their conclusions are controversial — scientists must learn to tell stories rather than report cold facts, for instance — but they deserve discussion.