Writing in 2003, the American environmentalist Bill McKibben observed that although “some small percentage” of scientists, diplomats and activists had known for 15 years that the Earth was facing a disastrous change, their knowledge had almost completely failed to alarm anyone else.

It certainly alarmed McKibben: in June 1988, the scientist James Hansen testified to the US Congress that the world was warming rapidly and human behaviour was the primary cause – the first loud and unequivocal warning of the climate crisis to come – and before the next year was out, McKibben had published The End of Nature, the first book about climate change for a lay audience. But few others seemed particularly worried. “People think about ‘global warming’ in the way they think about ‘violence on television’ or ‘growing trade deficits’, as a marginal concern to them, if a concern at all,” he wrote in 2003. “Hardly anyone has fear in their guts.”

McKibben’s words appeared in the literary magazine Granta, which I then edited, in a piece I’d commissioned for an issue on global warming: This Overheating World. It seemed a timely and important theme, but sometimes editors can get too far ahead of the game. Many thousands of people across the world felt more and knew more about the climate crisis than I did, but few of them, unfortunately, appeared to be literary novelists or writers of narrative non-fiction. The issue included some fine pieces but was not a total success. In fact, Margaret Atwood did publish a novel that year, Oryx and Crake, set in a world ruined by climate breakdown (among other causes), but the most prominent examples of its fictional treatment, the small genre sometimes known as “cli-fi”, had still to come. Cormac McCarthy’s The Road, published in 2006, may never be surpassed, not even by the Book of Revelation, as the future’s most terrifying herald.

Literature had good reasons to resist. I’m never sure what the German philosopher-sociologist Theodor Adorno was driving at with his statement that “to write poetry after Auschwitz is barbaric”; only that he might be suggesting that in the prospect or memory of such a calamity, poetry was useless and the pretension of its relevance simple-minded. And so it might be with novels and the climate crisis. Earlier writers such as Jules Verne and HG Wells entertained their readers with versions of the future that were sometimes frightening, but only in a hide-beneath-the-bedsheets way, and against the common grain of western optimism that the future would be better than the past (a feeling that survived the Eurocentric horror of the last century’s first 50 years, and, in my generation’s case, the Cuban missile crisis and the threat of nuclear war).

Who believes it now? The idea of a better future has been replaced by one of a future not as bad as it could be, providing urgent steps are taken; but for more than 20 years (more than 30 years, if the counting starts with Hansen’s address to Congress) the science behind our understanding of climate breakdown was widely dismissed either as an international conspiracy or an inconvenient speculation, or relegated to a problem on a par with McKibben’s “growing trade deficits”. National electorates and their political leaders; media magnates; company stockholders and executives, especially those in the carbon fuel business: few of them wanted to know. As recently as 2015, Boris Johnson could describe worldwide concern over the climate as “global leaders driven by a primitive fear that the present ambient warm weather is somehow caused by humanity”. In 2012 Anne-Marie Trevelyan, now his international trade secretary, wrote in support of a campaign against windfarms: “We aren’t getting hotter, global warming isn’t actually happening.” As the gospel of St Luke tells us, there will be more joy in heaven over a single sinner who repents than over the 99 righteous people who don’t need to bother, but here on Earth it might be appropriate to have statements such as Trevelyan’s (she made several) incised on durable measuring sticks that can be inserted along the high tidemark of her Northumberland constituency, whose coastline is so long and low.

It would be wrong, however, to confine the blame for our delayed engagement to straightforward denialism. Recognising climate breakdown as a possibly terminal crisis for civilisation led to the difficulty of managing it inside our heads. As David Runciman, professor of politics at Cambridge University, wrote six years ago: “It’s hard to come up with a good analogy for climate change but that doesn’t stop people from trying. We seem to want some way of framing the problem that makes a decent outcome look less unlikely than it often appears.” He listed the most common analogies: climate was a “moonshot problem”, a “war mobilisation problem”, a “disease eradication problem”. Beyond giving a notion of the effort required, none worked; war, for instance, needed a clear enemy in view – and in the climate crisis, Runciman wrote, “the enemy is us”. Analogies offered a false comfort: “Just because we did all those things doesn’t mean we can do this one.”

Climate breakdown is like nothing that has gone before. Like an intermittent fountain, its ghastly prospect shoots high in the air one minute and then vanishes as though it had never been. On 9 August this year the Intergovernmental Panel on Climate Change published a report that spread alarm and despondency everywhere. “A code red for humanity,” warned the UN secretary general. “The alarm bells are deafening, and the evidence is irrefutable: greenhouse gas emissions … are choking our planet and putting billions of people at immediate risk.” By 11 August, A-level results, Brexit lorry queues and Prince Andrew had squeezed the message from every front page.

An ordinary kind of life goes on. Research shows that in 2020 the word “cake” was mentioned 10 times more often on UK television shows than the phrase “climate change'”, and that “banana bread” was heard more frequently than “wind power” and “solar power” combined. Research shows that four in 10 young people around the world are hesitant to have children, while three-quarters of them find the future frightening and more than half believe humanity is doomed. Research (by the climate scientists James Dyke, Robert Watson and Wolfgang Knorr) shows that if humanity had acted on Hansen’s testimony immediately to stop the accelerating use of fossil fuels and begun a decarbonisation process of around 2% a year, then we would now have a two-in-three chance of limiting warming to 1.5C. If that calculation is correct, the odds these days must be quite a lot longer.

Is there fear in our guts? Boris Johnson spoke to the UN assembly on Wednesday like a boy who wanted the applause of the Oxford Union. He had a clever reference (Sophocles), a popular reference (The Muppet Show), and a reference to a particular kind of English life (“unlocking the drinks cabinet”) that vanished with the Austin Allegro. It seems unlikely that the world can be saved by such a speech, but there is no point complaining. For this dangerous moment, he is what we have.

• Ian Jack is a Guardian columnist