The World Without Us

In the mid-20th century, the length of commercialized wheat stalks shortened nearly by half even as the number of grains they bore multiplied. They were engineered crops, developed during the so-called Green Revolution to eliminate world hunger. Their phenomenal yields fed millions who otherwise might not have eaten, and thus also contributed to expanding the populations of countries like India and Mexico. Designed through forced crossbreeding and random mixes of amino acids—tricks that preceded gene splicing—their success and survival depend on calibrated cocktails of fertilizers, herbicides, and pesticides to protect these laboratory-bred life-forms from perils that lurk outside, in reality.

In a world without people, none will last in the wild even the four years during which wheat hung on in the Broadbalk Wilderness after Lawes and Gilbert abandoned it to the elements. Some are sterile hybrids, or they spawn offspring so defective that farmers must purchase new seed each year—a boon for seed companies. The fields where they are destined to die out, which are now most of the grain fields in the world, will be left deeply soured by nitrogen and sulfur, and will remain badly leached and acidic until new soil is built. That will require decades of acid-tolerant trees rooting and growing, then hundreds of years more of leaf litter and decaying wood broken down and excreted as humus by microbes that can tolerate the thin legacy of industrial agriculture.

Beneath these soils, and periodically disinterred by ambitious root systems, will lie three centuries’ worth of various heavy metals and an alphabet soup of POPs, substances truly new under the sun and soil. Some engineered compounds like PAHs, too heavy to blow away to the Arctic, may end up molecularly bound in soil pores too tiny for digesting microbes to enter, and remain there forever.

IN 1996, LONDON journalist Laura Spinney, writing in New Scientist Magazine, envisioned her city abandoned 250 years hence, turned back into the swamp it once was. The liberated Thames wandered among the waterlogged foundations of fallen buildings, Canary Wharf Tower having collapsed under an unbearable tonnage of dripping ivy. The following year, Ronald Wright’s novel A Scientific Romance jumped 250 years more, and imagined the same river lined with palms, flowing transparently past Canvey Island into a sweltering mangrove estuary, where it joined a warm North Sea.

Like the entire Earth, the posthuman fate of Britain teeters on the balance of these two visions: a return to temperate foliage, or a lurch into a tropical, super-heated future—or, ironically, into a semblance of something last seen in England’s southwestern moors, where Conan Doyle’s Baskerville hound once wailed into chill mist.

Dartmoor, the highest point in southern England, resembles a 900-square-mile baldpate with occasional massive chunks of fractured granite poking through, fringed by farms and patches of woods that exploded from old boundary hedgerows. It formed at the end of the Carboniferous Age, when most of Britain lay submerged, with sea creatures dropping shells on what became its buried chalk. Beneath that was granite, which 300 million years ago bulged with underlying magma into a dome-shaped island—which it may be again if seas rise as high as some fear.

Several ice ages froze enough of the planet’s water solid to drop ocean levels and allow today’s world to take shape. The last of these sent a mile-high ice sheet right down the Prime Meridian. Where it stopped is where Dartmoor begins. Atop its granite hilltops, known as tors, are remnants from those times that may be portents of what awaits if yet a third climatic alternative proves to be the British Isles’ destiny.

That fate could occur if meltwater from Greenland’s ice cap shuts down, or actually reverses, the oceanic conveyor atop which rides the Gulf Stream, which currently keeps Britain far warmer than Hudson’s Bay, at the same latitude. Since that much-debated event would be the direct result of rising global temperatures, probably no ice sheet will form—but permafrost and tundra could.

That happened at Dartmoor 12,700 years ago, the last time the global circulation system nearly slowed to a halt: no ice, but rock-hard ground. What followed is not only instructive, as it shows what the United Kingdom might resemble in coming years, but also hopeful, because these things, too, will pass.