The rising threat of UK coastal erosion

Several coastal regions of the British Isles are under threat from erosion, but attempting to hold back the waves is an expensive business

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By Mark Rowe

There’s a wry joke among coastal geologists and surveyors that goes like this: ‘How far is that house from the sea?’ The reply: ‘About five years.’ Natural erosion has affected the coast for as long as Britain has been an island, but evidence is building that climate change is starting to accelerate the process. 

News bulletins may focus on individual properties at immediate risk, on the lives and dreams tipped upside down, but the macro implications of erosion on our coastlines are significant. These include not only the loss of homes and businesses but damage to infrastructure and agricultural production. Inundation from the sea means that flooding could become more severe, extensive and prolonged; groundwater is likely to become more saline, adding pressure to constrained freshwater resources. Shoreline defences are likely to be tested as never before. 

Geographers, planners and industry are being forced to ask some difficult questions: how long can we continue to maintain or upgrade defences; to what extent can we manage realignment; or should we simply let nature take its course? 

Rising threats

The British Geological Survey’s (BGS) GeoCoast datasets, which inform coastal adaptation, note that ‘low-lying coastal areas are already vulnerable to inundation [but] with increasing sea levels and storminess, impacts could be felt over a wider area than we think.’ The BGS puts the number of properties now within 25 metres of potentially highly susceptible coast at 30,000. 

The UK will almost certainly have to adapt to at least one metre of sea-level rise at some point in the future, according to the Committee on Climate Change (CCC); even a 0.5-metre rise is projected to make a further 20 per cent of England’s coastal defences vulnerable to failure. ‘Climate change is an amplifying factor; we’re seeing increasing wave stress on the coast,’ says Richard Millar, head of climate adaptation at the CCC. ‘A relatively small number of properties are at direct risk right now, but that will grow substantially. The impacts will be incredibly local and depend on the geology.’

The CCC identified 520,000 properties in England alone, including 370,000 homes, in areas at future risk of damage from coastal flooding. Looking at the worst-case scenario – which excludes the likelihood of building more sea defences or other mitigating measures – the BGS data suggests that some one million properties are at potential risk from inundation by 2050, increasing to 1.25 million by the 2080s and 1.35 million by 2100.

As for national infrastructure, the BGS calculates that 1,600 kilometres of major roads, 650 kilometres of railway line, 92 railway stations and 55 historic landfill sites are at risk of coastal flooding or erosion by 2100. In an observation that seems almost superfluous, the CCC report, Managing the Coast in a Changing Climate, adds that, in the future, ‘some coastal communities and infrastructure are likely to be unviable in their current form’. Pertinently, the CCC report notes that ‘this problem is not being confronted with the required urgency or openness’ and that the public, by and large, is unaware of these risks.

It’s easy to seek comfort in the misconception that erosion is an issue only in fragmented parts of our blissfully rugged coastline. Yet the fact that coastal erosion is not on the radar is bemusing. As Millar points out: ‘To some extent, you can recover from other impacts, such as flooding, but coastal erosion tends to be pretty permanent.’ The BGS believes that as much as 15.5 per cent of Britain’s coastline has a high susceptibility to erosion and a study by the London School of Economics found that erosion is happening more rapidly along coastlines made from softer sediments, notably on the east coast of England. Counties such as Lincolnshire, Hampshire, Norfolk and Lancashire have a high percentage of low-lying, weak coastal landforms that are at risk from increased storminess and wave attack. 

The effects of erosion have long been apparent. Happisburgh in Norfolk has lost 35 homes in recent years and Norfolk’s history of coastal erosion dates back centuries, as evidenced by the so-called ‘lost villages of Norfolk’ (Eccles, Keswick, Waxham Parva, Newton, Foulness, Ness, Shipden and Clare). Birling Gap in Sussex has lost its terraces and the Belle Tout Lighthouse, perched above the English Channel, was moved 17 metres inland in 1999 to protect it from the failing cliff.

Yet the fact that the potential number of homes at risk is above one million is because this is an issue that affects cities. In Scotland, the problem, according to Alistair Rennie, project manager for Dynamic Coast, a Scottish government research project, is that a large number of Scotland’s assets are clustered in erodible areas. ‘Towns, cities with their major roads and housing, and ports tend to be at river mouths,’ he explains.

Around Britain

Scotland’s geology is different from that of much of the UK, particularly England. Around 80 per cent of the coastline is made up of hard rock, only 19 per cent is erodible and one per cent comprises hard engineering. Yet half of Scotland’s erodable coastline is already declining and this will increase due to sea-level rises linked to climate change. Erosion affects 46 per cent of soft shorelines (up from 38 per cent reported in 2017), with an average erosion rate of around 0.43 metres per year. ‘If we do nothing, £1.2 billion of assets will be at risk within 30 years in Scotland,’ Rennie says. 

Several high-profile Scottish locations are in the crosshairs of coastal erosion. Rennie points to the Bay of Skaill in Orkney, home to the Neolithic site of Skara Brae. ‘Places like this are genuinely priceless from a historical point of view, as well as for tourism,’ he says. Other locations include the post-industrial town of Dumbarton, St Andrews, with its important golf and wider tourism sector, and Hebridean islands such as South Uist and Tiree. ‘Whether it’s north, south, east or west, tourism, industrial, historical, urban or rural, the issue of erosion confronts every element of Scotland’s society.’ The threats faced by Golspie, a highland east coast village, apply to many other rural communities. ‘It’s on the coast, is spread along a main road; there’s a ribbon of communities in the same position.’

Wales also faces less of an immediate threat from sea incursion than England, according to Patrick Robson of Aberystwyth University, who is involved with the CHERISH project, which studies climate change and its impact on the heritage located on the Welsh and Irish coasts. This is because of the underlying hard-rock geology – siltstones, mudstones, volcanic rocks – that defines much of the coast. Instead, Wales is witnessing more oblique forms of coastal erosion. Since much of the hard rock is resistant, the threat of erosion tends to come from rainfall. Robson sees this at Dinas Dinlle, a glacial deposit overlooking the Menai Strait that’s buried under a layer of sand and has an Iron-age fort on top. ‘We’re not seeing greater averages in rainfall across a period of time, but it’s more intense when it comes and that surface water can accumulate and erode the hill bit by bit,’ says Robson. In turn, the silt washed into the straits is slowly bolstering the spit of Morfa Dinlle, which is developing just to the north. 

Coastal communities won’t be immune to erosion and climate change, warns Robson. ‘The unknown factor is how quickly we get an equivalent sea-level rise. We don’t have a good handle on that because sea rises aren’t like filling up a bath – it will be higher in some places than others. You then have to put higher tides and storms on top of that. This will make or break places that we can live.’

Finding solutions

‘Coastal erosion is a natural process that has always happened and always will,’ says Rennie. ‘Transportation and deposition are the other side of that coin and are key to natural defences. Nature does much more for us than we think. Our natural defences are three times greater in value than the [land protected by] engineered defences.’

In Scotland, £5 billion of assets are protected by artificial defences, while £14.5 billion are protected by natural defences. More than 9,000 buildings, 500 kilometres of road, 60 kilometres of rail track, 300 kilometres of water supply lines and airport runways, such as that on the island of Islay, are protected by natural defences. 

Sand dunes and saltmarshes are the obvious defences that can be enhanced, but Rennie points to offshore bulwarks. ‘Sandbars can take a big chunk of energy out of the waves before they hit the shore. These things happen out of sight. But if we continue dredging offshore, then these sandbars erode and natural defences become less effective, the waves will just come rolling in. We need to manage that offshore environment in a sympathetic way.’

Elsewhere, reinforcing low points in dunes can make a significant difference. Along the coast of St Andrews, Christmas trees have been buried within dunes and marram grass planted on top in order to reinforce them against waves.

Yet saltmarshes, mudflats, shingle beaches, sand dunes and sea cliffs, which provide natural protection against waves and storm surges, are declining in area. The BGS describes many dune sites as being ‘in fragile equilibrium’. Excluding mudflats, these environments declined in extent by 20 per cent between 1945 and 2010, from around 62,000 hectares to 49,000 hectares (frustratingly, these figures haven’t been updated since 2010).

Intervening against coastal erosion is where things can get political because projects tend to come with eye-watering price tags. According to DEFRA and the Environment Agency, the cost of fortifying the coast rings in at around £5,000 per metre. This means any hard-engineering project faces hard questions. ‘I’m not against them in principle,’ says Rennie, ‘but you have to ask, will it be effective and how long will it last? The problem is that we don’t have the money to do it forever. As a default approach, we won’t always be able to rely on engineering as the first or easy solution.’

In some locations, society may be happy to pay the costs to protect against inundation and coastal erosion. The Thames Barrier, opened in 1984, cost £461 million (£1.4 billion in today’s money) and because it prevents flooding across an area home to 14 million people, another £54 million has been set aside to enhance the barrier against rising sea levels by 2070. But such cost-benefit analyses can involve tight calls.

The BGS points out that the 2019 Bacton sandscaping scheme in North Norfolk cost £22 million. This raised the beach level by about seven metres in places and protects a gas terminal and adjacent village. Yet the project will only be effective for 20 years. At Mullion Cove in Cornwall, the National Trust has funded several rebuilds of the harbour wall, costing more than £2 million, as winter storms become more frequent and stronger. The trust has recognised that there may come a point where rebuilding is no longer financially possible. The Hampshire coast is currently the beneficiary of the largest local-authority-led project to strengthen coastal defences, aiming to reduce the threat of flooding to around 10,000 homes and 700 businesses. The cost for the 4.5 kilometres of new defences is £130 million. 

There’s another option. Land previously reclaimed from the sea could be allowed to reflood, removing the need for ever-costlier defences. Yet without consultation, this is unlikely to meet with local agreement. ‘There is no easy way around tough decisions,’ says Millar. These conversations, adds Rennie, ‘will be very hard. We will see more of this. Local authorities right across Scotland are having these discussions – it’s not a problem for just one or two coastal places.’

Yet letting the land go entirely doesn’t automatically mean a hands-off approach. With some thought, suggests Millar, this could be combined with natural defences, so that ‘the line is loosely held’ in a way that doesn’t involve engineering. He envisions scenarios in which land is allowed to transform into saltmarsh, accompanied by a transition in local farming, for example, with the introduction of sheep where crops were grown before. At the same time, Millar believes, local communities must be consulted well ahead of such decisions – perhaps decades ahead – so that people can relocate slowly rather than suddenly being faced with losing their homes. 

‘You’re looking for a win–win situation where you see improvements for nature and communities remaining in some form,’ he says. ‘But everyone has to have a clear sense of what is going to happen, or is likely to happen. People will want it to be seen to be fair and for it to be transparent.’

Raising awareness

A palpable sense of urgency and frustration emanates from the individuals and organisations who track coastal erosion and its interaction with climate change. ‘We don’t see there is a vision [at the political level],’ says Millar. ‘There’s more complexity in adaptation – in developing that vision of what a climate-adapted UK looks like – than in emissions-control targets.’

Robson admits it’s difficult to rustle up enthusiasm for action, except in places directly affected, which tend, for now, to be smaller communities with little clout on the national stage. ‘If a smattering of houses at Nefyn [on the Llyn Peninsula] falls into the sea, a lot of people will ask “so what?”, and take the view, rightly, that it is more important to prevent flooding in the major cities,’ he says. ‘But if you own one of those houses you may disagree.’

Rennie draws parallels with one of the lessons of the waves of Covid-19 infection – that it’s better to respond sooner rather than later. ‘The risks are growing far quicker,’ he says. ‘If you react earlier, it is easier to deal with things than if you move too late after things have really kicked off.’ His Dynamic Coast project concluded that the time to act is now. Its modelling suggests that the 2020s is the decade in which erosion will first influence most shores. It’s also the decade in which inland low-lying coastal flood-risk areas are most at risk from erosion-enhanced flooding. Not only is natural coastal erosion inevitable, but the impacts of climate change on the coast are baked in, says Millar. ‘Even if we meet the targets of the Paris Agreement we will see still higher seas and weather changes for a hundred years or more,’ he says.

‘Should we be alarmed?’ ask Rennie. ‘Yes, that’s a natural human emotion – but I’m relatively positive. Although the science on climate change is stark, we have never had so much technology, data in front of us to inform us. We don’t have to be perfect, but we need to grab it. We need to be nuanced. The smart money is on picking our fights with the sea.’