Coastal erosion in Norfolk. Photograph: Graeme Robertson
It was the latest in a series of catastrophic floods. Seawater forced its way through sand dunes and spilled miles across the low-lying lands of north-east Norfolk, spoiling farmland and destroying homes. After this flood of 1622, it was proposed that the sea be allowed in for good, as far as the village of Potter Heigham, five miles from the coast. Local people and landowners were horrified. They vowed to defend their livelihoods. Two thousand men were press-ganged into repairing the dunes and repelling "the extordinaire force and rage of the Sea".
The strategy worked and the waves were turned away from this corner of Norfolk for nearly 400 years. Last month, however, a new plan, closely resembling the retreat first proposed in the 17th century, was leaked to the public. Calling for "the embayment" of 25 square miles of low-lying land, the government's environmental body, Natural England, said that nine miles of sea defences between the seaside villages of Eccles and Winterton were unsustainable "beyond the next 20-50 years", creating the possibility of "realigning the coast". What this cold academic language actually means is wiping part of Norfolk off the map: 600 homes, six villages, five medieval churches, four fresh-water Broadland lakes, historic windmills, precious nature reserves and valuable agricultural land would be given up to the rising seas. Britain would have its first climate change refugees.
Outrage has greeted this "secret" plan. Residents complain of an instant property blight on their apparently doomed homes. Farmers speak out against the needless destruction of agricultural land. Politicians point out that no one has been consulted. Conservationists protest at the loss of unique flora and fauna and almost an eighth of the unique Broads national park. But the scientific community is unrepentant. They fear that, unlike in the 17th century, community spirit and construction of new barricades will no longer be enough to hold back the sea.
More than 15 million people live close to Britain's coastline. This small corner of Norfolk is the first to confront what every low-lying community in the country will face in the coming decades: the real cost of increased erosion, storms and sea-level rises exacerbated by global warming. It presents local people and the government with a stark dilemma. Is it worth spending billions on defending homes and livelihoods? Or, faced with inexorable sea-level rise, should expensive coastal defences be abandoned, leading to the evacuation of land and houses?
It is not just old pillboxes from the second world war that make the clifftops at Happisburgh, in Norfolk, resemble a battle scene. The land looks as if it has been bombed by the sea. Neat furrows of winter wheat end abruptly at the cliff edge: this erosion is happening so fast that crops planted last autumn to be harvested this summer have already been lost to the sea. A concrete ramp that once took the lifeboat down the cliff lies in twisted ruins. Dilapidated houses are being deserted as their gardens flop into the sea. On the beach, twists of exposed metal lie across fragments of smashed wooden sea defences and newer boulders lobbed there by the council.
To the south, the defences have been allowed to disappear completely from a half-mile stretch of beach. Here is compelling evidence of what happens when sea defences are abandoned: the sea has blasted a new bay out of farmland and, in less than a decade, marched several hundred metres inland. The authorities have a name for what is happening here in Happisburgh: "managed retreat". It does not look very orderly.
The Norfolk Broads begin on ominously low land a couple of miles south of Happisburgh. They were originally estuary, but since Saxon times have been steadily drained and reclaimed as grazing marsh. Its freshwater lakes were mostly created by peat digging, and for centuries its waterways have been managed by windmills, water pumps and dykes, often based on Dutch engineering. This land has always lived with the water, although one inland village, Hickling, which would be sacrificed to the sea under the new proposals, lost 108 people when it was swamped by sea water in 1287. Dramatic floods returned in 1938 and again in 1953, when a sea surge killed 307 people. This disaster triggered a "never again" attitude and the construction of miles of concrete sea defences to protect the east coast. These are now crumbling.
One Happisburgh resident, Malcolm Kerby, has formed an action group to protect coastal communities. He calls the principle of managed retreat "the government's 'chuck it all away today' philosophy".
"We're not stupid. We know we live on a coast that's been eroding for thousands of years. We know we will never stop the sea," he says. But he points to where the wooden defences remain shakily intact and then the spectacular erosion behind the section where they have disappeared. "What is demonstrated here so clearly is that for a relatively low cost you can reduce the rate of erosion to a manageable level."
The rhetoric of the government and its agencies, however, appears to doubt that. "I think the Norfolk Broads will go. They will definitely salinate," Lady Young, chief executive of the Environment Agency (EA) - responsible for defending Britain's coastline - told a recent climate change conference. Hilary Benn, the environment secretary, has warned that tough choices will need to be made along Britain's coast. "It's very difficult for people living there; for farmers, for communities," Benn has said. "It's partly about how much money we're prepared to spend, but it's also about what nature in the end makes happen."
The Department for the Environment Food and Rural Affairs (Defra) has nearly doubled spending on flood and coastal erosion risk management from 10 years ago to an estimated £600m in 2007-08 and will invest £2.15bn in the next three years. But land is already being abandoned to the sea. The EA says it will not fund long-term defences of the Blyth estuary on the Suffolk coast, leaving local volunteers to rebuild flood barriers. Managed retreat is already happening on a smaller scale at a number of locations including Cley, a bird-watching mecca on the north Norfolk coast, where a protective shingle bank is being allowed to fall into disrepair, leaving the sea to form new salt marshes behind it.
The EA has a policy of "holding the line" for the next 50 years to protect this part of Norfolk. Even then, it will cost between £1.5 and £2m a year just to maintain the nine miles of sea defences between Eccles and Winterton, which protect the 25 square miles that could be flooded. "In economic terms it's well justified," says Steve Hayman, EA coastal manager for East Anglia - but probably not beyond 50 years. "In the longer term there are really difficult questions to answer here and it may not be possible to maintain the coastline as we know it today."
The proposals to sacrifice this chunk of Norfolk were first mooted in environmental circles five years ago. Although they were leaked last month, Natural England clearly wanted them to be published. "By selecting a radical option now, the right message about the scale and severity of the impacts of climate change is delivered to the public," its document said. As well as catastrophic coastal erosion, it predicted "strong political resistance". It has been proved right.
In the affluent, attractive village of Hickling, local residents fear thousands have been knocked off the value of their homes. "It puts a blight on the area," says Harry Purnell, vice-chairman of the parish council. "It's not as if we're going to flood next week." Yvonne Pugh, who runs a B&B in a £700,000 house, says, "The idea of building a sea wall behind us and letting us go to ruin is not nice. What's it going to do for house prices?" Her husband, John, a retired chartered surveyor, says homes in the area are worth £2bn in total; farmers believe land lost would be worth £500m.
In Happisburgh, where erosion is so brutally evident, there is already a blight on houses. Locals claim prices are up to 30% lower than in unthreatened coastal villages. Mark Bradley, 46, lives on Beach Road. It would be worth £200,000 but after two decades of erosion, Beach Road is almost on the beach. When he bought it 23 years ago, he believed the government would continue to defend the coastline. Now, living in a house he can't sell and which may not be standing in a decade, he feels his life is ruined. "I went through a stage when I checked the cliffs every day. I got very upset and very depressed. You feel like a goldfish in a bowl when people come to gawp," he says. "Last year, when the new rocks were put on the beach [as a temporary sea defence], I decorated for the first time in 10 years. Previously I didn't have the heart to spend £100 on wallpaper because you don't know how long you're going to enjoy it for."
It is not just homeowners who are in shock. While local environmental groups such as the Norfolk Wildlife Trust have spoken hopefully of valuable new salt water habitats if this part of the Broads is submerged, many conservationists argue that we must preserve the unique freshwater nature reserves at Hickling and Horsey. "The whole future of the Broads is at stake. We can't possibly just 'let nature take its course'," says Martin George, an ecologist and former chairman of the Broads Society. "It's diverse and very species-rich, with a lot of very rare species. I am apprehensive that some of the naturalist groups are inclined to say how wonderful it will be to have all these new [salt marsh] habitats for birds. I disagree fundamentally. We need to do what we can to save what's there now. But I'm realistic enough to say we may not be able to do that for longer than 20 to 50 years."
George argues that the Broads should be saved for as long as they can be. "A country that has the technological know-how to extract oil and gas from below the North Sea and convey it in pipes to the mainland should surely be capable of finding a way to protect a concrete sea wall against the effects of climate change," he says. "We should accept that ultimately we will get drowned, but to let all these insects and land and communities go into the sea is simply not acceptable. Philosophically, as a conservationist, I believe we should do our damnedest to safeguard our heritage for as long as humanly possible."
Most climate and environmental scientists, however, predict that this corner of the Broads may not last long. "It is very vulnerable. It could go next winter or we might be lucky and several decades pass," says Brian Moss, professor of botany at Liverpool University, who has studied the Broads for 35 years. "Do you wait for it to happen and have another 1953 with potentially a lot of people killed, or say the risk is so high that it goes back to an estuary, you pay compensation and move people out before flooding it? That's the controversial view."
David Viner, Natural England's leading climate change specialist, explains that the plan was a draft series of "scenarios". Defending the coastline has not been ruled out and he insists that it backs the EA's pledge to "hold the line" in Norfolk for the next 50 years. But he says Natural England is showing "good leadership in facing up to the challenges of climate change. It is irresponsible to put your head in the sand and say nothing is happening." Hickling Broad won't survive another 100 years, he says. Even if it is protected with new sea walls, saline intrusion from rising sea levels will irrevocably transform the Broads from a freshwater region into a salty one. Some freshwater species will become extinct in Broadland. "We will have to look at recreating Hickling and the communities around Hickling somewhere else," he says.
While Natural England's plan does not rule out alternative options, such as building new sea defences, many environmental scientists argue against "hard" defences, and not just on the grounds of cost. Research shows that big sea defences can cause as many problems as they solve, stopping the transfer of sand along the coast and causing erosion elsewhere. New defences in north-east Norfolk could increase erosion at Great Yarmouth, which is equally vulnerable to sea-level rise, warns Moss.
As coastal residents become aware that they may outlive their homes, the government faces a huge new dilemma. Malcolm Kerby says that people should be compensated for the loss of their homes to the sea, just as they are if houses are given up for motorways or airports. Here, however, the government is sheltering behind an obscure 1949 law that absolves it of responsibility for homes lost to the sea. The government still won't contemplate the question of compensating our climate change refugees of the future. "We do not offer compensation, in line with previous governments," says a Defra spokeswoman. She says Defra does not intend to examine whether it will in the future. "We are developing a toolkit to help communities adapt to the fact that the coastline is changing, where we cannot get in the way of natural processes - but that's not compensation."
Kerby argues that it is discriminatory to protect some people from rising seas and rivers and not others, so London is saved by its expensive Thames Barrier but tiny Happisburgh is not. The vast bulk of the government's spending on flood defence goes on non-coastal areas, protecting towns and cities from river floods. Defra has asked the EA to ensure that a minimum of £110m - just 5% of its £2.15bn three-year flood defence spend - is reserved for projects by coastal local authorities. "Officials say leave it to natural processes. By all means, remove all the sea defences down the east coast including the Thames Barrier and I'll take my chances with the rest of them, but they are singling us out," says Kerby.
This battle for our future climate change refugees is only just beginning. For some, however, fighting the sea is a familiar story. John Buxton has lived on the Broads for 76 years. His father bought Horsey Hall in 1929, later donating his land to the National Trust. Buxton still helps look after this rich habitat and vividly remembers the flood of 1938, which turned his home into an island. Salt water covered thousands of acres - a disaster for farmers if it could not be removed. There was no question of giving it up to the sea, though: his father travelled to Holland for advice on how to recover the land.
Buxton, and many other locals, feel they should do the same today. Buxton believes that Dutch sea defences - with a slow, gradual slope - are far more effective than the wall-style defences that now protect the Norfolk coast.
"I see it as my responsibility to maintain this land. I'm not King Neptune. I can't keep the sea out, but I can advise on ways of managing the land," he says. "It works, the way we do it. There has always been this danger about the sea coming in but to allow it to do so, or encourage it to come in, is complete nonsense and shows utter ignorance and disdain for what has happened up until now. Taking care of this land has been a life's work. Giving it up would be a waste of my lifetime's efforts".
· There is a gallery to accompany Patrick Barkham's piece: guardian.co.uk/g2
