“London has been flooded many times. Until the late 19th century, and the construction of the Thames embankments as part of Joseph Bazalgette’s grand sewerage works, the high-water mark of the tidal river was an arbitrary dividing line between liquid and solid. All along the river’s banks there was a fretwork of jetties and inlets, and when the waters rose too high they would inundate the streets.

“Even after the embanking, in 1928, a flood breached the parapets in Westminster and surged into the impoverished streets around Millbank, drowning 14 people. During the great North Sea floods of 1953, London was relatively unscathed – although in the East End, Canning Town went under the waters, while still further downriver Canvey Island was entirely inundated, with the loss of 58 lives. This event led directly to the construction of the present Thames Barrier, the centrepiece of which is a series of silver-cowled sluice gates ranging across the river between Silvertown and Charlton; structures that resemble – for all their obvious utility – sections of the Sydney Opera House, disarticulated and marooned on the riverbed.

“The barrier was completed in the early Eighties, and since then has been employed with greater and greater frequency as combinations of storm surges and high equinoctial tides have threatened the city. Many believe these historically high water levels are a result of global warming, a climatologic phenomenon widely thought to be caused by human activity, specifically the release of so-called greenhouse gases since the Industrial Revolution. But whatever the new, physical threat to London, the city has felt itself to be psychically vulnerable for centuries.”

Read the rest of Will Self’s new introduction to the Folio Society’s new edition of JG Ballard’s The Drowned World at the Telegraph here.