Imaginative rationalist

Bald, short, fat, clever, Ian McEwan's latest protagonist gorges on junk food, routinely cheats on his myriad wives and lovers, robs a dead employee of his breakthrough ideas about cheap renewable energy, and rests in his randy, portly way on the laurels of the Nobel Prize in physics that he won many years before.

Surely no biographical truth could ever match this florid fiction? Yet McEwan, the most consistently science-friendly major writer of his age, has, even at this early stage, felt the shock of recognition from his collaborators on the other side of the "two cultures" divide.

"A couple of them have already written to me saying, 'I'm a bit worried that your Michael Beard rather resembles so-and-so down at the Centre'," he tells me.

A warming carbon-fuel fire burns in the hearth of the corner house on an august London square where he lives with his wife, the author and journalist Annalena McAfee.

After those emails, "I thought, Oh my God! But fortunately, two or three individuals have been named." Libel lawyers should not hoist their hopes too high.

"I seem to remember that Flaubert was faced with almost 40 lawsuits from pharmacists who all thought they were Monsieur Homais [the pompous schemer from Madame Bovary]. So that's self-cancelling."

A selfish and greedy hedonist who can by his pampered mid-50s no more pursue an original theory than he can see his own toes, Beard still seeks to serve humankind by harnessing the power of our near star for cheap, safe energy, so consummating a "cranky affair with sunbeams" that began in his shining student days. Long-awaited and avidly debated, McEwan's Solar is a fiction in which climate change and the wavering human response to it supply what he calls "the background hum".

Both a comedy and a parable, his 12th novel enlists an array of headline issues and a repertoire of trademark McEwan-esque torques and wrenches to tell "a story of hubris, folly and something intrinsic in human nature".

Absurd but not quite irredeemable, Beard comes to stand limply for all our planet-threatening, stuff-your-face proclivities. On a short flight back to London from Berlin, for instance, he wolfs down an entire premium-fare meal, champagne to chocs, after his dietary good intentions last for 10 nanoseconds or so.

Only the grapes remain untouched. "In business class now," comments McEwan, "they put before you a bowl of heated salted nuts. Try resisting those."

A hypocrite and a rogue (or "complete bastard", as his creator puts it), but one whose mind still takes him down the road to truth, Beard will emerge into intellectual weather rather different to the conditions that bred him. Three years ago, McEwan's virtuosic early-1960s period novella On Chesil Beach came out (he's currently at work on the screenplay of a film, for the director Sam Mendes).

At the time, he told me of his intention to write some kind of fiction around climate change. The grandest conceptions of modern science and their precarious habitat in our frail skulls and frames had, after all, loomed large in the unfolding of his fictions at least since his 1997 novel, Enduring Love.

Often he has shown how our embodied minds aspire to intellectual miracles and then sink down into the mortal mechanisms of impulse and instinct, of blood, tissue and bone. "Owning a body becomes a more onerous affair as you get older, of course - it gets fatter, heavier and iller. Life becomes impacted by resolutions that are carried out feebly."

Given his outlook and his gifts, how could McEwan avoid the slow warming of the planet: that arena in which human dreams and hopes run up most bruisingly against the laws and limits of the physical world?

All the same, "I was having difficulty thinking how on earth one could do this subject," he recalls. "It seemed too intractable for fiction: too serious, too impacted with statistics, figures, science - really hard science too. Most of all, it seemed rather unwieldy because of the moral weight of it."

Shunning the dystopia and apocalypse as over-familiar dead ends, even in 2007 he saw the scope for humour and fable rather than breast-beating earnestness. Solar more or less conforms to the recipe he sketched back then - sharp, droll, even skittish, but with an undertow of sadness and even dread beneath the satirical surf.

A princely has-been, burnt out but still flattered like royalty, Beard may owe just a little to the Nobel laureates McEwan met at a conference at Potsdam in 2007 organised by his friend John Schellnhuber, the German government's climate-change adviser: "I was the after-dinner entertainment."

There, "I was struck by how grand they were - some of them comically grand in the way neither Seamus Heaney nor J.M. Coetzee are. They run fiefdoms in a way that writers can't, or don't - or shouldn't. These guys were politicians as well as scientists."

Among the secular idols, "I really got the sense of a glow of holiness - rather like in medieval paintings. The glory is almost tangible ... Within their field, they are demigods. They do live an enchanted life."

What has altered since that formative moment, when the character of Beard "emerged from the gloom" on the plane back from Berlin, is the mood of lay opinion about man-made temperature shifts. Beard, the double-standard baby-boomer, a cosseted child of an "arrogant, shameless, spoiled generation", might to some mischievous eyes look like the fictive answer to a climate-change denier's dream.

McEwan remains adamant. To him, genuine "scepticism" remains an honourable position. But the current gale of doubts and sneers about the intellectual edifice behind climate-change theory has no validity at all.

Above all, "The denier case is just parasitic ... They do not send satellites up; they do not crawl across the planet trying to make these difficult measurements, even though they are hugely funded by bodies like Exxon and energy-lobby think-tanks. Let's all be sceptics. Present some data. Do some measuring. Show us that the Earth is getting cooler or staying the same, and that this is just an uninteresting fluctuation. The case really has to be made the other way round. We know the physics by which a molecule of carbon dioxide traps radiant heat. And we know that we put lots of carbon dioxide into the air, trillions of tons. We would expect the climate to shift; we see it happening. So the burden of proof is the other way around."

McEwan's role as British literature's prime champion of scientific theory and practice has a cutting edge these days. A satirical segment of Solar draws on his 2005 trip to the Svalbard archipelago as a guest of Cape Farewell: the project that brings creative types face-to-face with the actuality of global warming amid the thinning Arctic ice of the 79th parallel.

Only a reader (or colleague) who had suffered a triple sense-of-humour bypass could object to the motley crew of hippie ice sculptors and conceptual choreographers with whom Beard shares a symbolically messed-up boot room on board ship ("Only good laws would save the boot room. And citizens who respected the law.").

Yet a later episode, when Beard voices mild support for the evidence of sex differences in the aptitude for science and maths, has an altogether angrier buzz.

The scientist's assumed sympathy for "genetic determinism" sees him pilloried by a radical audience at the ICA and vilified in the media as a "neo-Nazi professor".

McEwan is drawing on his own, and friends', ordeal by media here. As for today's intellectual liberal-left, McEwan alludes with distaste to "the automatic hostility to speakers because they're Israeli. There's a shocking aspect to some corners of British public life, and a sort of stirring of anti-Semitism on a mild scale."

Mostly, however, Solar shows how "blank slaters" who believe that nurture accounts for everything and nature for nothing target those scientists, and their allies, who wish to investigate the ways in which genetic inheritance might shape our selves and skills.

Solar proves that McEwan has not softened his scorn towards the sort of post-modern philosophy that presents the objects of scientific research - even genes themselves - as mere "social constructions": "There's a daftness about it."

He tried out these ideas on his elder son, William (one of two, now in their mid-20s), a geneticist now based in Cambridge.

"The scientists don't really know about this stuff; it doesn't come their way. So the philosophers of science are quite a closed group."

Although vain, foolish and dishonest, pudgy old Beard does, thus, get to share several of McEwan's firm convictions. A tender reverie about his first marriage has the washed-up Nobel laureate remembering how he wooed lovely Maisie, an English student at Oxford, by mugging up on Milton in a week.

Does his contempt for soft, artsy courses reflect a consensus among scientists?

"It's not among scientists - it's among me. I have this suspicion that people like you and me had, as undergraduates, a very easy time. I see it among my children's generation. You do a soft subject like French or English, you tumble out of bed at midday for three years, you have occasional panics with essays and a bit of reading. But on the whole, you're on holiday compared to the scientists."

When Will studied biology at University College London, 9-5 lectures, practicals and weekend work meant that "it's a job - and a whole body of knowledge is being absorbed".

Meanwhile, in Solar, "I honestly felt a slightly wicked and not entirely defensible impulse to say: it is a lot harder to get your mind around the General Theory of Relativity than to understand Paradise Lost."

Born in Aldershot in 1948, the son of a career soldier from Glasgow who survived Dunkirk (and whose experiences fed the battle scenes of Atonement), the young McEwan emerged as a writer from a base-hopping forces childhood across three continents.

At the University of East Anglia, and afterwards, he polished his prose and cultivated his plots with a dedication to craft that gave the wild counter-cultural adventures of the mid-70s stories in First Love, Last Rites or In Between The Sheets an awesome sense of precocious control.

In the non-fictional world, McEwan can see few heavy-duty alternatives to fossil fuel, save for the one source that he once denounced. During the missile jitters of the early 80s, he wrote the anti-nuclear oratorio "Or Shall We Die?" As for civil nuclear power, "I started out very much against it." But now, "There isn't that much else on offer."

He recalls, "I was at the top of the Post Office Tower at the end of last year: a beautiful, clear night; freezing cold. I was looking miles in every direction at glittering London and thought, 'how beautiful it is. How can you run this? Not with wind generators tonight'. If you want not to burn fossil fuels alone, you only have one other powerful source."

What about the risks?

"I don't think we should scare ourselves with a handful of failures. Far more have died in coal mining and the burning of coal. There are more than 450 nuclear power stations in the world and they generally work fairly well. The problem with nuclear has been its links to the armaments industry, and the lack of openness and transparency: the lying one always associates with the nuclear industry - lying about costs, lying about leaks."

McEwan's nuclear option still leaves space for private commitments to a low-waste lifestyle as "a way in which everybody can engage with this at some personal level ... But it's not the solution. It just means that we'll get to where we're going two years later."

Besides, "Having a dog is more energy-inefficient than having an SUV. Six million people are not going to get rid of their dogs."

Still, several millions may give house-room to a novel by Ian McEwan.

His stature and popularity in Britain, which spiked sharply after the canonical grandeur of Atonement in 2001, goes along with an ever-rising profile internationally.

Around our feverish planet, readers of Solar will grasp that the faults and follies of scientists do not demolish the value of their work. The message could hardly be timelier.

"You can't have a conspiracy of scientists," the imaginative rationalist insists, praising the peer-review process that secures an open forum for fresh ideas.

"They're always tearing each other's stuff down ... It works by slow accretion and endless fine adjustments. We don't have another thought system that accepts error, and adjusts itself and realigns itself in the light of new data, in quite the same way. Religions don't. They bed down with sacred texts."

In fiction, McEwan accepts nothing as sacred - except the quest for truth.

- INDEPENDENT