At this week's memorial service for Eric Hobsbawm, who died last year aged 95, several speakers touched on the distinguished historian's scepticism about the world's ability to improve itself. As Professor Hobsbawn was a lifelong Marxist and therefore once the advocate of a disastrous cure, the causes of his pessimism had a clearer definition than most, but he knew himself well enough to see the funny side. Professor Leslie Bethell reminded the audience at London University's Senate House that Hobsbawm's favourite non-European country was Brazil, where he found in Lula da Silva's Workers' party a reason to be cheerful; it remains one of the few successful political parties in the world to have been founded by organised labour in the second half of the last century. Lula fought and failed to be elected as his country's president three times as Hobsbawm cheered distantly from London NW3, and then in 2002 he succeeded. To celebrate, Hobsbawm brought out the champagne, and he and Bethell clinked glasses. "And now," he announced cheerfully, almost as a toast, "we wait to be disappointed."

This behaviour fits perfectly with what Pascal Bruckner describes as the "strange mixture of fatalism and activism" that according to him was a striking characteristic of the communist left. Bruckner is a French philosopher, an essayist and novelist who was in London last week to publicise his new book, The Fanaticism of the Apocalypse: Save the Earth, Punish Human Beings. Beneath that frightening title lurks a superficially attractive message: we need to stop beating ourselves up about climate change because no good will come of it. Bruckner sees "ecologism" as a successor to communism: at the turn of the century the age of revolutions became the age of catastrophes, and the previous "long list of emblematic victims – Jews, Blacks, slaves, proletarians, colonised peoples" was replaced by the planet, "which has become the paragon of all the wretched … the absolute outcast". In the name of saving it, "all the foolishness of Bolshevism, Maoism and Trotskyism" was reformulated so that "all these authors, journalists, politicians, and scientists compete in announcing the abominable … they alone see things correctly, whereas others vegetate in the slumber from which they will some day awaken, terrified".

There is comfort here. Even to people like myself – the kind who would answer "Obviously!" to the question "Are we all doomed?" in the New Statesman's regular Q&A interview while marvelling at the delusion of people who reply to the contrary – Bruckner's book offers the cheering possibility that our depression has internal rather than external causes; that, as in the non-believer's view of religion, it springs from the human imagination rather than the direct impress of real events. Its cause, according to Bruckner, is the "catastrophism" and self-hatred that stems from western decline. The enemy is no longer just capitalism, but humanity itself. "For centuries we have waged war on the world by trying to dominate it," he writes, satirising the ecologist's position. "Now we have to wage war on war [and] sign an armistice with water, trees, stones, and oceans."

Bruckner's prose is assertive and aphoristic and sometimes his arguments are memorably expressed. Ecologism is basically a good thing, "the sole truly original force of the past half-century", but badly served by the green prophets of decay and decomposition who "beat the drums of panic" and call on us to repent before it's too late. The fear of science and technology "reflects a time when humanity, and especially western humanity, has taken a sudden dislike to itself. We are exasperated by our own proliferation, and can no longer stand ourselves … Cataclysmic ecology reflects the triumph of guilt: children must pay for the errors of their elders – progress, development, consumerism. It inaugurates a universe saturated with crimes, mourning, sorrow: the profanation of nature must be sanctioned by an implacable punishment."

All very bracing, though it soon becomes obvious that not even the milder propositions of the ecological movement will please him. On the one hand, Yves Cochet, a Green MEP, is mocked for his radical and unpopular idea that any parent with more than two children should face higher taxes; and on the other, moderates such as Al Gore are ridiculed for believing that long-life light bulbs and bicycles will have any effect. "The enormity of the diagnosis, the absurd inadequacy of the remedies" is the way he puts it. What then? Trying to establish a median "between reasonable warning and sterile panic", Bruckner concludes that "we have to count on the genius of the human race", meaning ingenious technical fixes that wait to be discovered, unknown unknowns.

When we met at his Westminster hotel, I suggested that this something-will-turn-up approach would be familiar to a character in David Copperfield. If the prevailing anxiety was catastrophist, then surely he was a Micawberist. He liked the idea: something-will-turn-up expressed his thinking almost perfectly, he said. Despite the rhetorical certainty of his book, he was happy to confess contradictions. There was even a kind of innocence about him, which seems an odd thing to say about a French philosopher in his mid-60s who numbers among his achievements a novel that Roman Polanski turned into a film (the forgotten Bitter Moon) and polemics on multiculturalism and "Third-World sentimentalism" that would have warmed the heart of VS Naipaul.

His London trip was part-funded by the Global Warming Policy Foundation, which includes Nigel Lawson among its luminaries and queries the scientific consensus on climate change – in contrast to Bruckner, who doesn't contest the predictive science and believes firmly in renewables. But the purpose of the GWPF, and the sources of its funds, seem never to have occurred to him as questions worth asking. It was the pessimism of the greens that inspired his anger – the attitudes formed by the science rather than the science itself. It set what Bruckner considers "the dominant temper" of the present century by closing factories and blocking plans for new roads, airports and railways.

The dominant temper doesn't seem to me that way at all. Google, Rio Tinto, Coca Cola, BMW: capitalism powers on, with a few moral ornaments added, such as green manifestos departments dealing in corporate social responsibility. In that sense, you could argue people haven't been frightened enough. As Bruckner concedes, "in situations of all-out war, foreseeing the worst is a proof of lucidity". His book quotes the remark made by the director Billy Wilder in 1945: "The optimists died in the gas chambers, the pessimists have pools in Beverly Hills."

Unlike the speakers at Senate House this week, I can't claim to have known Hobsbawm well. He was kind to me a couple of times; when I'd presumed to question a fact in one of his books, I was struck by the care and generosity of his reply. But mainly I knew him as as a general reader whose understanding of the past his work had enormously enriched. I can hardly judge what others saw as his despondency, what one speaker called his ability to see history as "a chronicle of fear". All I know from the record is that Eric Hobsbawm left Berlin for London in 1933, the year Wilder left Berlin for Hollywood, the year Hitler came to power. If pessimism and its allies alarm and anxiety need an endorsement, here it is.