Oceans can be charted; land can be cultivated; forests can be pruned and even cleared; but between humans and wetlands exists, always, a state of undeclared war. Swamps, marshes, fens: they can be subdued or submitted to, but never lived with. Alongside geographic extremes of tem- perature and altitude, wetlands are solitary inheritors of the pre-human world. The last, lonely outposts of the unconquered earth.

It’s unsurprising, therefore, as Annie Proulx describes in Fen, Bog and Swamp, that we should hate them. Land that can’t be traversed, waters that can’t be plumbed, forests without soil. “Wilderness is the spatial correlative of unreason,” writes one historian: “of madness, of the unhuman anarchy that informs so many folk tales emphasising the ephemeral stability of Christianity, society and agriculture.”

That shadow of madness – the taint of the ambiguous and amphibious – makes wetlands fitting alembics for the compound, circular unmaking of climate change. Sequestered CO2, long hoarded by rainforest and peat bog, escapes under the ungentle ministrations of farmers and ranchers. Three stubborn centuries of con- stant effort drained the fenlands of England; two years of war dried the storied marshes of Iraq. Triumph to disaster, and worse. Retreating swamplands in prospect spelt prosperity; in hindsight, they presaged doom.