Rising sea levels have already forced flood planners in Portsmouth to draw up controversial plans for a large wall at the seafront.
But now it has been suggested - by the Environment Agency and others - that some communities across Britain can no longer be protected but that it would instead be better to instead ‘move [them] out of harm’s way’.
Experts have suggested this could work to save Portsmouth – using less densely-populated areas as ‘sacrificial lambs’, diverting water to them in a bid to reduce flooding in the city – and in Gosport.
The suggestion has brought a fiery response from one borough council leader who insisted there would be nothing sacrificed ‘on anybody’s altar’.
It comes as Environment Agency chairwoman Emma Howard Boyd yesterday said: ‘In some places, the scale of the threat may be so significant that recovery will not always be the best long-term solution.
‘In these instances, we will help communities to move out of harm's way.’
Ms Howard Boyd was speaking as her agency warned at least £1bn a year needs to be spent on traditional flood and coastal defences in the face of climate change.
Robin Shepherd, a partner at planning and design consultancy Barton Willmore, warned that rising water levels of just 30cm to 50cm could see ‘big changes’.
Mr Shepherd called for an honest national debate about whether communities should be protected - or if they should be sacrificed for more populated communities.
He said: ‘Portsmouth and Gosport, yes absolutely, we’ll need to put, over time, bigger sea defences in place, divert water and we might forego certain areas in others areas to save the more populated areas, the sacrificial lamb.’
Asked which areas could be given over to the sea, he said: ‘It would have to be unpopulated or very low-populated areas.
‘We’ve got clusters of development and communities in Southsea, Portsmouth, Fareham, but in between those and especially around the river corridors, in my mind are those sort of things, you do something in those areas to encourage water to go in there to save other areas.’
Mr Shepherd insisted a properly co-ordinated plan was needed - with government stepping in to ensure people living in flooded areas could still get insurance, mortgages and if the area was to be sacrificed, the government could then buy up properties.
‘That’s where the government has got a role,’ he said. ‘In those areas over the next 50 years they will be given over to the sea and communities within them they will help relocation, [government could] help purchase the property, underpin for insurance or mortgage. It’s got to be a co-ordinated plan.’
He added: ‘The Environment Agency is right to plan for the worst and in some cases moving communities rather than just shoring up what we have will be the better solution by far.
‘In some areas - for example on an island city like Portsmouth - defences may be the only workable solution, but the reality for many areas will be a combination of the two. The question is, how do we decide which areas to protect and which areas to let go to the sea?’
‘There now needs to be an honest debate and a national plan that looks at infrastructure, planning and sea defences.
‘We have all the information we need on climate change and its implications - now it's a case of taking it seriously and having an honest debate that looks at infrastructure, planning and the reality of the problem - and from that, make a national plan than can be implemented at a UK-wide, regional and local level.’
Fareham Borough Council leader Sean Woodward said Titchfield - which he said could be targeted by such plans to give up areas - would never be sacrificed ‘on anybody’s altar’.
He said government allocates sea defences cash based on the density of housing - with the borough council forced to pay out around £1m on defences at Hill Head.
Councillor Woodward said: ‘On the face of it, it sounds pretty crazy - the area meant by that would be the medieval village of Titchfield - we’re not about to sacrifice that for anybody.
‘That’s where the river Meon is and it does burst its banks, we’re not going to be sacrificing the medieval village of Titchfield on anybody’s altar.’
Portsmouth City Council is in the middle of working on major plans for the Southsea Coastal Scheme - which is designed to protect 8,000 homes and 700 businesses should a ‘one in 200’ chance flooding happen.
Yesterday Ms Howard Boyd, who backed has backed Portsmouth’s £10m bid for cash for the defences, warned ‘we cannot win a war against water’ by building ever-higher flood defences, and efforts are needed to make communities more resilient to flooding.
Homes hit by flooding need to be ‘built back better’, with improvements such as raised electrics and hard flooring, while some communities may have to be helped to move in the face of growing risks of flooding and coastal erosion.
The warning comes as the government agency publishes its long-term strategy for managing the risk of flood and coastal erosion.
It is planning for the potential of up to 4C of warming, well beyond the 1.5C or 2C limits which have been agreed internationally and are seen as thresholds beyond which dangerous climate change will occur.
The EA also predicts that climate change and population growth are set to double the number of properties built on the flood plain over the next 50 years.
Ms Howard Boyd said urgent action was needed to tackle more frequent, intense flooding and sea level rises driven by rising temperatures, and called for more resilient homes and infrastructure.
WHAT IS HAPPENING IN PORTSMOUTH?
WARNINGS from the Environment Agency will not change plans for defences in Portsmouth, the council chief executive has said.
David Williams, who is in charge of Portsmouth City Council, said: ‘The report from the Environment Agency will not have any direct bearing on the Southsea Coastal Scheme, which has been designed to provide flood defences that will protect more than 8,000 properties and 700 businesses from a 1 in 200 year flood event.
‘Climate change and rising sea levels have been factored in as part of the extensive research and modelling stages of the scheme design.
‘The Environment Agency report highlights the need for coastal communities to understand the very real risk of coastal flooding especially in densely populated areas - like here in Portsmouth.
‘We are already working in partnership with the Environment Agency to ensure our flood defences are rebuilt in accordance with their strategy.
‘Emma Howard Boyd, chair of the Environment Agency, has visited Portsmouth and met me. She is supportive of the scheme and has publicly supported a £10m bid by Portsmouth City Council to Solent LEP towards its funding.
‘Throughout multiple public consultation events, the proposed flood defences have been designed so that, where appropriate, the shingle beaches work in conjunction with the new defence to minimise the visual impact and maintain the character of the coastline.
‘The Southsea Coastal Scheme has carried out three rounds of public consultation to shape the principal flood defence designs which will be submitted for planning approval shortly.
‘A series of public information events will be held during the last week in May. These will address the key themes raised through the previous public consultation and provide further information about the planning process and future scheme activities.
‘Should planning approval and scheme funding be secured, work could begin on the first section of flood defences in 2020 with a view to completing the entire project by 2026.’