Almost a third of all homes which could be lost to coastal erosion this century are in Norfolk, a climate action group has warned.
The organisation, One Home, identified 21 at-risk communities using Environment Agency data.
Of these, six were in Norfolk: Overstrand, Trimingham, Mundesley, Bacton, Happisburgh and Hemsby.
The group's research has been released on the 70th anniversary of the North Sea floods, when 307 people were killed on the east coast - including 100 in Norfolk - when a storm surge broke through coastal defences.
As part of the study, One Home also compiled a map highlighting what shoreline management plans (SMPs) are in place in different areas of coast and the level of protection.
It shows long stretches, particularly on the north coast, which are designated as 'no active intervention', where there has been a decision not to provide or maintain sea defences.
Other parts are marked on the map as areas of 'managed realignment', where the shoreline will be allowed to retreat or advance.
Some are marked as 'hold the line' areas, meaning that defences will be maintained and upgraded if funding is found.
Policies on whether to defend, retreat or abandon sections of coast are contained in SMPs, which are developed by coastal groups with members mainly from local councils and the Environment Agency.
Angela Terry, chief executive of One Home, said: “Sea levels are rising as global temperatures soar and so larger waves batter our coast during severe storms.
“These irreversible changes mean some cliff faces are crumbling fast.
“We can’t turn the tide or build a wall around the entire coast so we urgently need to help seaside communities to prepare for the damage that will come.
“Shoreline management plans are publicly available documents but most people are unaware of their existence.
“Many homeowners don’t know their properties are at risk or that decisions have been made about whether to protect them or not.
“Funding is not guaranteed so even where communities have been chosen to be saved, the money might not be there, giving people false hope that their home will be protected long-term.
“One Home’s aim with this map is to explain SMPs in an easy-to-digest way so that homeowners are sufficiently informed to make timely decisions about their properties to reduce future harm.
“Currently, for those homes at risk, there is no compensation scheme available."
More than a third of England’s coastline has a designation of 'no active intervention', One Home said, meaning that nothing will be done.
The shoreline management plan for the area between Kelling and Lowestoft, overseen by North Norfolk Council, says their continued defence is "not sustainable" and while current defences will be maintained where possible, the longer-term strategy is one of "gradual retreat".
As well as Norfolk, the other areas of England identified by One Home as likely to lose the most homes are in Cornwall, Cumbria, Dorset, East Yorkshire, Essex, the Isle of Wight, Kent, Northumberland and Sussex.
The value of property damages, on the land that could be hit by coastal erosion by 2100, was estimated at £584 million using average local authority values or site-specific values from Rightmove, One Home said.
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