L OCOMOTIVES HAVE plied the Dawlish railway seawall, which hugs Devon’s beaches between Exeter and Newton Abbot, since 1846. Passengers are treated to magnificent views of the English Channel—and occasionally to a frisson, when rough seas break on the concrete groynes and envelop oncoming trains in sea spray. If, that is, the trains are running, which increasingly they are not. Service was suspended for a day in mid-October after storm Callum wrecked a culvert. In 2014 the line closed for two months to repair storm damage.

Such disruptions are likely to become more common. A report published on October 26th by the Committee on Climate Change, which advises the government, warns that rising waters pose a growing threat to England’s shores. They have edged up by 15cm (six inches) since 1900 and could rise by another 50-80cm by the end of the century, as a result of man-made global warming. Unlike Kiribati or other atoll nations, the sceptred isle would not be wiped off the map. But stretches of its coastline would be.

Besides 436km (271 miles) of railway, the authors identify 930km of main roads, 187,000 hectares of farmland and as many as 520,000 properties already exposed to a one-in-200 chance of coastal flooding each year. If Earth warms by another 1°C, which the world’s current policies all but guarantee, these figures could double, affecting 1.1m Britons. The committee puts the damage to properties alone at £370m ($470m) a year by 2080.

England appears unprepared (the report did not consider Wales, Scotland and Northern Ireland, which pursue their own policies). Councils rely on outdated planning guidelines. Homeowners in safe areas cross-subsidise the insurance of those in risky ones through Flood Re, a government-run scheme. The property market reflects clifftop villas’ breathtaking views rather than their hair-raising risk of tumbling into the sea.

Building seawalls and other defences to protect important stretches of shoreline from rising tides could cost £6.4bn-9.2bn. Big cities like Liverpool or Newcastle can count on help when the water comes. But a tenth of the 1,600km of endangered coast may prove too uneconomical to safeguard, according to the report. Its authors will not say where; that is up to the government. But imperilled residents surely deserve to know.