World’s beaches are disappearing due to the climate crisis because of human-induced erosion, and the UK is on course to lose a quarter of its sandy coast.
According to new research, almost half of the sandy beaches worldwide will have retreated significantly by the end of the century because of climate-driven coastal flooding as well as human interference.
This sand erosion will pose a threat to wildlife, and coastal settlements could suffer a heavy toll for no longer having buffer zones to be protected from rising sea levels and storm surges. Moreover, government measures to mitigate against the damage can become increasingly expensive and also unsustainable in some cases.
The scientists for the Joint Research Centre (JRC) of the European Commission have identified 36,097km (22,430 miles), or 13.6% of sandy coastlines from satellite images that would have destroyed by erosion in 30 years. The situation will be worse in the second half of the century, and a further 95,061km or 25.7% of Earth’s beaches will be washed away, they predict.
This climate breakdown is a scenario known as RCP4.5, and these estimates are far from the most catastrophic. However, scientists rely on an optimistic forecast of international action to fight. In this scenario of reduced melting of ice-cap and lower thermal water expansion, oceans will only have risen by 50cm by 2100.
However, as per the Intergovernmental Panel on Climate Change, sea levels will rise by an estimated 80cm if the emissions of carbon continue at its current rate. A total of 131,745km of beaches, or 13 percent of ice-free coastline on the planet, will go underwater if this happens.
In the RCP4.5 scenario, the average shoreline retreat will be 86.4 meters globally or 128.1 meters in the high-carbon scenario. But the amounts will vary vastly between locations. Compared to the coastlines where waterfronts are steeper, flatter or wilder coasts will be more affected or those maintained artificially as part of coastal development.
The UK will lose 1,531km or 27.7% of its sandy coast in the best-case scenario, otherwise 2,415km (43.7%) in the worst case. The worst-affected countries will be Australia (14,849km lost) and Canada (14,425km) as predicted, followed by Chile (6,659km), Mexico (5,488km), China (5,440km) and the US (5,530km). Although Gambia and Guinea-Bissau have short coastlines, more than 60% of theirs are also predicted to lose.
As per the study, the hardest-hit areas in the UK will be west Dorset, north Devon, Great Yarmouth, Barrow-in-Furness, and north-east Lincolnshire. The beach retreat is predicted to be five times the national average in these areas.
“The length of threatened seashores incorporates locations that will be submerged by more than 100 meters, assuming there are no physical limits to potential retreat,” said Michalis Vousdoukas, an oceanographer at the JRC and lead author of the study, published in the journal Nature Climate Change.
“Our 100-metre threshold is conservative since most beaches’ width is below 50 meters, especially near human settlements and in small islands, such as the Caribbean and the Mediterranean.”
The beaches that are large on the Atlantic and Pacific coasts and the Australian side of the Indian Ocean will narrow by 100-200 meters, and that will also wipe out more than 60% of sand deposits in many developing countries that are heavily dependent on coastal tourism and economically fragile.
However, swift action for limiting emissions and tackling climate breakdown could help reduce the impact as per experts. “Moderate emissions mitigation could prevent 17% of the shoreline retreat in 2050 and 40% in 2100, thus preserving, on average, 42 meters of sand between land and sea,” Vousdoukas said.
Based on the 30 years of observations, the researchers projected the future anthropogenic and geological changes.
The construction and barriers on the shoreline, including buildings, roads, or dams, have changed the natural replenishment cycle of sandy beaches. Above all, sea-level rise is exacerbating the problems.
“In the UK, part of manmade erosion results from protecting cliffs whose wearing would normally top up the associated beaches with gravel,” said Robert Nicholls, the director of the Tyndall Centre at the University of East Anglia in Norwich. “This happens, for example, in Bournemouth, to safeguard luxury properties built on top of fancy viewpoints.”
In some regions, marine erosion is compensated by land rise, as in the case of the Baltic. Sometimes sediments may also be brought by rivers naturally as in the Amazon, or residues accumulate from industrial sites upstream resulting from artificial activities as in the Chinese deltas.
The intensification of storms that are associated with climate breakdown is the third driver of erosion, and these further erode the most vulnerable beaches. The British seashores facing most erosion are the east and west coasts, which are more exposed to tidal surges than the south as the study predicts.
Worldwide low-lying coastal regions of up to 63% will be threatened by the century end. Both population density and development tend to be higher in these areas than inland.
“Seaward human expansion will continue, mostly in unspoiled coastlines that are particularly extensive in Asia and Africa,” Vousdoukas said. “Adaptive measures are urgently needed.”
The cost of protecting the shoreline in many places often outweighs the benefits. For example, in 2017, a £62m sea wall was built to protect the tourist resort of Blackpool. But such concrete defenses are seen as more of a problem than a solution besides requiring indefinite spending on maintenance. These can disrupt the process by which ocean currents deposit sand and thus further exacerbating erosion.
The Environmental Agency has chosen sand dredged offshore to replenish beaches in some places. Mining sand from the seabed is expensive and also harmful to marine habitats. The replenishment of the 20km seafront between Skegness and Mablethorpe in Lincolnshire costs millions of pounds yearly since 1994 and also to help preserve 35,000 hectares of farmland.
Dr Sally Brown, deputy head of life and environmental sciences at Bournemouth University, said: “Building defenses helps maintain coastline position, but defenses are known to reduce beach width or depth over multiple decades. Responding to sea-level rise means looking strategically at how and where we defend coasts today, which may mean protecting only limited parts of the coast.
“Beach nourishment schemes can help the problem, such as in Bournemouth, but these beaches need a regular top-up. Ultimately, we cannot nourish everywhere forever, meaning that hard decisions need to be made about how much to spend and how to manage the coast in decades to come. This could affect those living on the coast, and tourists who enjoy the sandy beaches too. Sea-level rise will only make this situation worse.”