Dozens of coastal communities face surrender to the sea and their residents moved because of erosion.
Happisburgh is one of the communities which could go
Draft government plans for Norfolk and Suffolk's coastlines due out this week say artificial defences fail to solve problems and should be abandoned.
Prof Tim O'Riordan, of the University of East Anglia, said: "The Government now believes defending coasts against natural forces is unsustainable.
"A workshop in Norfolk this week talked about benefits of controlled retreat."
Responsibility for coastal management is shared by DEFRA and the Environment Agency which have close links to local authorities, organisations such as English Nature and the universities.
The University of East Anglia is also taking a leading role in developing policy under the leadership of Prof O'Riordan, the head of environmental sciences.
He said: "People have until the end of the year to discuss the plans and I am sure the first reaction of those communities affected will be a sense of betrayal by a cruel and insensitive government.
"But it is clear that the aggressive nature of the sea will mean defences will continue to be undermined.
Defences or compensation
"Vulnerable communities must think of relocating. I know they will be angry and frustrated at the loss of businesses and property but it is not a short-term need.
"We have time for a planned retreat from places like Happisburgh, Overstrand and Mundesley."
A report by civil engineers Halcrow has set out estimates about £250m worth of property is under threat, including 220 houses and 35 commercial properties.
Malcolm Kerby from the Happisburgh Coastal Concern Action Group said he was shocked by the reported attitude of the Government.
"We either have to have our defences replaced or we have to have compensation," he said.