About 70 per cent of the surface of the Earth is covered in water. For billions of years, the boundaries between sea and land have been in flux. The volume of water has risen and fallen in parallel with rises and falls in the temperature of the planet.

And the topography of the land has changed as a result of earthquakes, tectonic shifts and the deposit of sediment. Parts of the world that are land today were once sea, and parts that were once sea are now land.

Until recently, minor shifts in the shoreline did not matter very much to the life of the planet.

But now they do, for several more or less unrelated reasons. Some economic activities – such as building ports and catching sea fish – are necessarily conducted on the shoreline.

The deltas of great rivers such as the Ganges, the Mississippi and the Rhine provide fertile agricultural land that supports dense populations. And people like living by the shore. Sea views and beachfront locations add greatly to the value of a house.

Sea flooding
The worst sea flooding western Europe has experienced for 50 years is a reminder that even modest and temporary advances of the sea can have substantial costs. The 2004 tsunami in the Indian Ocean and Hurricanes Katrina and Sandy were damaging to property and life because so much economic activity takes place on the shoreline.

No one wants the sea to advance. But almost nobody wants the sea to recede either. True, Holland and Monaco have recovered valuable land. But the beautiful Belgian city of Bruges was for several hundred years one of the great commercial centres of Europe, and lost that status when it ceased to be a port. Occupants of beachfront and sea-view residences want beach and sea to stay just where they are.

So we have created powerful vested interests, businesses and property owners, who want the shoreline to remain unchanged in perpetuity. These lobbies want taxpayers’ money to be spent on achieving this outcome.

Yet the history of the world tells us that this unnatural objective is likely to be formidably expensive even if it is technically possible.

The shore people
When the sea defies mankind's efforts to keep it in place, the shore people want these costs, too, to fall on the public at large. In the aftermath of a disaster it is difficult to argue with such demands. Victims of Hurricane Katrina legitimately felt the United States government should have been there to help. When Hurricane Sandy hit, everyone rallied around. The world donated generously for the victims of the Asian tsunami. And while history tells us archipelagos come and archipelagos go, we are understandably reluctant to say that to the inhabitants of the Maldives.

But when the storms have abated and calm returns, it is hard to see why those who cannot afford sea views and beachfront properties should subsidise those who can, or why commercial activities related to the sea should not meet the costs that proximity to the sea entails. (Full disclosure: I own a property with a sea view in France. French government arrangements mean that, in effect, the cost of flood insurance is pooled between all residents, whether their property is in the Alps or the areas of the Landes and Gironde that are gradually disappearing into the Atlantic.)

It is almost impossible to reconcile the objectives of flood-control policy: solidarity in disaster, fairness between different home occupiers, spending neither too much nor too little on flood prevention, and discouraging people from building vulnerable properties. Different countries have adopted different solutions and most are thinking of changing to something else.

Controversial plans
The US has an insurance scheme similar to that of the French but messier and more complex. The US is, controversially, attempting to move to a more market- based approach. The UK has equally controversial plans to move in just the opposite direction.

The Netherlands has socialised the whole system – flood insurance is not available but the government has generally picked up the bills. With Dutch flood risks apparently well controlled, proposals have been made to move back to a private market.

(Further disclosure: I also own a property that is about as far from the sea as it is possible to be in England. I think both my properties should be rated according to the flood risk they pose.)