‘I like to think of this as my mid-life crisis novel,’ says David Mitchell. ‘I’m not going to run for office, I’m not going to buy a sports car, I don’t have the stamina for an inappropriate mistress, so I’ve written The Bone Clocks.’ On the phone from his home in Cork, the twice-Booker shortlisted English author, best-known for his 2004 genre-straddling epic Cloud Atlas, is on engaging form, despite having been up half the previous night reading Neil Gaiman’s The Ocean at the End of the Lane (‘it absolutely gripped me and I wolfed it down in one sitting’). Clearly happy to be able to talk about his own new book after four years buried in writing, he is ‘only now starting to work out’ what The Bone Clocks is all about.

Like Mitchell’s previous novels, The Bone Clocks (currently on this year’s Booker longlist) offers storytelling on a vast scale, beginning in a working-class Gravesend pub in 1984 and ending in 2043 with the world on the brink of total technological collapse as oil supplies dwindle and societies crumble. It is thrillingly enjoyable, zipping through multiple perspectives, dizzying shifts of genre and tone and seamlessly intertwining fantasy and reality. Mitchell’s characterisation of it as a ‘mid-life crisis novel’ is telling: it centres, he says, on the question of ‘who gets to survive and how?’ and asks ‘if you could avoid ageing, if you could do this deal, and the only price was the amputation of your conscience, would you do it?’ It also considers the possible pitfalls that await a successful author in later life, thanks to a prominent character named Crispin Hershey, a self-regarding author who has never been able to recapture his early success. ‘As you age as a writer,’ Mitchell reflects, ‘you need to think about how you can stay omnivorous, and in my case the temptation [is] to write versions of Cloud Atlas for the rest of my life – but not as good.’

The Bone Clocks is a confident confrontation of such temptation; with its six-stranded structure and lifetime-spanning timescale, it cleaves much closer to Cloud Atlas than Mitchell’s intervening two novels – the teenage semi-autobiography Black Swan Green and the rich and dense Japan-set period piece The Thousand Autumns of Jacob de Zoet – but never feels like an imitation. In fact, while Cloud Atlas was explicitly about the eternally continuing and repeating nature of life, The Bone Clocks finds Mitchell much less sure of our survival.

It’s a concern brought home powerfully by his damning assessment of our present reality – as he puts it, ‘the murderous headaches that we are bequeathing our children’ – found in the bleak future of The Bone Clocks’ final section. Mitchell again puts this down to the changed perspective that comes with age: ‘You become more civic-minded in your 40s. [I find myself] thinking more politically in ways that I haven’t done since I was an idealistic teenager. I don’t view myself as an out-and-out activist. However, if the last part of the book nudges people into thinking about political issues or assumptions that that section is founded on, then that’s great.’

That Mitchell can contain such weighty themes within a novel that can unreservedly be described as ‘fun’ is why he continues to be one of the most vital writers working today. Over an hour’s conversation, he proves to be endlessly fascinated with language, both as student (‘my next book will be set in the late 60s, and I’m collecting phrases – I just came across the grand old phrase “none of your beeswax”’) and practitioner, often speaking in rich metaphors: thoughts of a book’s potential success are ‘busy wasps at the picnic of the calmed mind’ while good editing can make a scene ‘really nutritious and crunchy and satisfying’.

His desire to remain ‘omnivorous’ recently drew him to Twitter. Not, he stresses, to follow Margaret Atwood and Gaiman into ‘full immersion’, but ‘to see what a story written in tweets would look like, what the problems would be and how those problems could be confronted, and maybe used to the story’s advantage.’ The resulting story, #TheRightSort, gives a flavour of The Bone Clocks’ mood in the way a teaser trailer hints at a film. ‘It’s from the same universe,’ Mitchell confirms. ‘The idea was around at the beginning of The Bone Clocks; I ended up putting it to one side and then, four years later, I wondered if I could rewrite it for Twitter. I didn’t just want to hack up an existing story into 140-character sections: each one’s a musical note or chord, and needs to work with what came before and what comes after.’ The experience has been a positive one for Mitchell and he is continuing it: ‘it’s swelling into a short sequence of about five, and that’s what I’m doing before my next novel.’

‘There’s just something vertiginously rewarding for me about making worlds,’ he says. If this is the result of David Mitchell’s mid-life crisis, then long may it continue.

The Bone Clocks is published by Sceptre on Tue 2 Sep. David Mitchell will be speaking at Assembly Roxy, Edinburgh on Thu 11 Sep at 7pm.