Protecting low-lying farmland with artificial dykes and sea walls is uneconomic, counter-productive and cannot be maintained in the long term, especially with the threat of sea-level rise caused by global warming, said the all-party Agriculture Select Committee in a unanimous report.
The committee called for a planned policy of "managed realignment" of the coastline rather than suffering "the consequences of a deluded belief that we can maintain indefinitely an unbreachable Maginot Line of towering sea walls and flood defences".
The MPs said: "It is time to declare an end to the centuries-old war with the sea and to seek a peaceful accommodation with our former enemy."
They argued that current coastal defence policy "cannot be sustained in the long term if it continues to be founded on the practice of substantial human intervention in the natural processes of flooding and erosion". Instead, they said, planners should be "making room for the sea at the coast and for rivers in flood plains".
Their report has major implications for the coast of eastern and southern England, in an arc from Yorkshire to Kent, especially around the Humber, the Wash and the Thames estuary, where much low-lying land has been reclaimed for agriculture by engineered defences.
The MPs said coastal planners should take into account the fact that Britain now no longer needs to produce all its own food, and too much food has often been produced anyway because of agricultural subsidies. If land was lost, affected farmers would have to be compensated, they said.
A spokesman for the National Farmers Union said the abandonment of low-lying farmland would have wide consequences throughout the industry. "Farmers must not be left at the mercy of the sea. The select committee is seriously oversimplifying the issues surrounding the use of low-lying farmland which is the basis for a large and important industry. Much of that land is used for horticulture which has an extensive associated industry for packaging and distribution."
"These are crops which are not produced in surplus and form a major source of export income for this country."
The World Wide Fund for Nature and the Wildlife Trusts welcomed the report, saying there was an urgent need to restore natural habitats in flood plains and along the coasts, especially the inter-tidal areas - the areas between high and low tides. These are not only immensely valuable for wildlife, said Paul Murby of the Wildlife Trusts, they are also extremely effective as coastal defences in themselves, as the shallowing shore absorbs wave energy.
Peter Luff, Conservative MP for Mid-Worcestershire, said that in many areas "managed retreat" would only require sea defences to be moved back a few tens of metres. But in others farmers would have to sacrifice land.
"We must work with nature and not against it - we must be a little more humble about our relationship with it," he said.