Seaside communities in some parts of the UK could be forced to move inland because of rising sea levels and erosion, the head of the Environment Agency has warned.
Sir James Bevan said that the "hardest of all inconvenient truths" was that "in the long term, climate change means that some of our communities - both in this country and around the world - cannot stay where they are".
Sir James was speaking at a flooding and coastal erosion conference in Telford as the Environment Agency launched a new roadmap setting out how it aims to tackle the growing threat of flooding from rivers, the sea, and surface water as well as coastal erosion.
It aims to protect new homes from flooding, safeguard vital infrastructure such as roads and railways and develop long term plans to manage what it describes as "future flooding and coastal change".
The agency said while communities could rebuild after river flooding, coastal erosion was a different matter because land could be left permanently underwater.
Sir James said: "In some places the right answer - in economic, strategic and human terms - will have to be to move communities away from danger rather than to try and protect them from the inevitable impacts of a rising sea level."
Sir James, who has been chief executive of the Environment Agency since 2015, said it was "far too early to say which communities are likely to need to move in due course, still less make any decisions".
He told the Flood and Coast Conference that "when we do eventually get to decisions on any relocation of communities, they must take full account of the views of the people who live there: no one should be forced from their homes against their will".
In places such as Happisburgh on the north Norfolk coast and parts of the coastline of the East Riding of Yorkshire, the Environment Agency is already working with local authorities and residents to plan for the long term.
Schemes include restoring and creating habitats to include green buffer zones, and replacing public or community-owned buildings in areas at risk with removable, modular, or other innovative buildings.
Many parts of the British coastline are being affected by the issue.
Homes have fallen into the sea at Hemsby in Norfolk and communities elsewhere are facing the loss of their homes.
Nowhere is that more evident than in Aldbrough - about 12 miles from Hull - where a whole community faces a stark reality.
Last year Alan Bartle, 90, who has lived in the affected area for 30 years, said he had watched successive neighbours lose their homes as the land beneath them had disappeared.
Sir James said while the aim was to help communities to remain where they were, "we do need to start the conversation now about the options, not least because we owe it to the threatened communities themselves to help them decide what they want their long-term future to be".
He added: "If we stick together I am confident that we can turn the climate crisis into an opportunity to create better places and a better future for all".
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