It is the year 2100 and England is four degrees hotter. Between the super-dense city tenements where most of us live, the parks are parched and dusty, or covered in porous artificial turf. What vegetation remains is mostly on the buildings as cladding to offset the burning heat. Children play on green rooftops. The roads are white for asphalt has been replaced with chalk to reflect solar radiation. Strictly rationed water is pumped out of deep aquifers and then recycled back. Londoners emerge in the "warmth-heavy night" to parade on the traffic-free streets like Spaniards.
In Sussex, Cuckmere Haven has turned into a tidal marsh. The surrounding downs are still there but we are not allowed to stray from the synthetic path onto precious grass. If we do, the trespass is noted by our mobile phones, and a fine automatically docked from our bank accounts. On the Suffolk coast, a new breed of fast reactor at Sizewell has become "a nuclear castle" on an island cleared of every sheltering bush and guarded by drones. The coastline will be unrecognisable, since much of it has vanished beneath the sea.
Britain has become a world centre of knowledge transmission. Industry has returned to its birthplace in the northern dales, where the new elite work from home. But the "fields of gold" will no longer be buttercups but "shards of light from golden solar panels and canopies of glass" on the exclusive "knowledge estates".
Nature will survive mainly in the Scottish Highlands. There, where human settlement is rendered impossible by midges and ticks, scrub will spread over the bare hills, except where wild fires wipe them clean again. Beavers and wolves roam free, successors of those we re-introduced a few decades back. It will look natural, but this wilderness is micro-managed by remote sensors and patrolled by air-traffic rangers.
The irony is that this hellhole will be, if Marek Kohn's predictions are right, one of the most desirable places on earth. People will be queuing up to come and settle, especially from parts of the world baked, drowned or otherwise rendered uninhabitable. "It's turned out nice after all", Kohn has us saying. Bournemouth and Eastbourne will be the new costas, though the elderly will have fled north.
The sting in the tail is that this nice weather precedes something unimaginably awful. By 2100, world carbon emissions will amount to 2,000 gigatonnes, enough to keep the global temperature raised by three degrees for the next thousand years even if human beings vanished overnight. Peering over the time horizon, Kohn sees ecosystems in collapse, mass extinctions, and, on our shrinking, overpopulated island, "squalls will turn into hurricanes and cracks into canyons".
Kohn's method is to analyse the likely climate-change effects in six different landscapes and one cityscape (London) before attempting a sketch about what life there will be like, circa 2100. As a science writer, he revels in technological ingenuity, in our acceptance of radical change as our surroundings lose their familiarity. No one grumbles in these pages. We will learn to live with rationing, accept being more or less rootless, and forced into communal eco-slums. It seems we will be cowed into a mindless submission to remote technocratic powers. Party politics will gradually merge into a muddy consensus.
This book's tone is sombre; it is densely written and quite a tough read. Kohn has done his homework, and there is a thick wad of references. But there are also acres of padding on the origin of London's parks, on "rewilding" schemes in Scotland and an obscure dispute over a visitor centre in western Ireland. This maybe "stark, authoritative" and "fiercely honest", but even in climate-change dystopias, the reader deserves a break. You lay down the book feeling bludgeoned and curiously disassociated.
Maybe fiction is the best way of engaging with approaching nightmares. Brave New World was genuinely frightening because it was presented with art and imagination, and so became convincing. Another way in might be a travel guide. What will the fishing be like in 2100? Will beer taste the same? A straight science lecture is, for this reader at least, like a sojourn in 2100 London's oppressive malls – crowded, noisy and in need of a refreshing breeze.
Peter Marren's 'Bugs Britannica' is published by Chatto & Windus