UK on course to lose a quarter of its sandy coast because of human-driven erosion
Almost half of the worlds sandy beaches will have retreated significantly by the end of the century as a result of climate-driven coastal flooding and human interference, according to new research.
The sand erosion will endanger wildlife and could inflict a heavy toll on coastal settlements that will no longer have buffer zones to protect them from rising sea levels and storm surges. In addition, measures by governments to mitigate against the damage are predicted to become increasingly expensive and in some cases unsustainable.
In 30 years, erosion will have destroyed 36,097km (22,430 miles) or 13.6% of sandy coastlines identified from satellite images by scientists for the Joint Research Centre (JRC) of the European commission. They predict the situation will worsen in the second half of the century, washing away a further 95,061km or 25.7% of Earths beaches.
These estimates are far from the most catastrophic; they rely on an optimistic forecast of international action to fight climate breakdown, a scenario known as RCP4.5. In this scenario of reduced ice-cap melting and lower thermal expansion of water, oceans will only have risen by 50cm by 2100.
However, if the world continues to emit carbon at its current rate, sea levels will rise by an estimated 80cm, according to the Intergovernmental Panel on Climate Change. If this happens, a total of 131,745km of beaches, or 13% of the planets ice-free coastline, will go under water.
Around the globe, the average shoreline retreat will be 86.4 metres in the RCP4.5 scenario or 128.1 metres in the high-carbon scenario, though amounts will vary significantly between locations. Flatter or wilder coastlines will be more affected than those where waterfronts are steeper, or those artificially maintained as part of coastal development.
In the best-case scenario, the UK will lose 1,531km or 27.7% of its sandy coast, and 2,415km (43.7%) in the worst case. Australia (14,849km lost) and Canada (14,425km) are predicted to be the worst-affected countries, followed by Chile (6,659km), Mexico (5,488km), China (5,440km) and the US (5,530km). The Gambia and Guinea-Bissau have short coastlines, but both are predicted to lose more than 60% of theirs.
The study predicts that the hardest-hit areas in the UK will be west Dorset, north Devon, Great Yarmouth, Barrow-in-Furness and north-east Lincolnshire. In these areas, beach retreat is predicted to be five times the national average.
The length of threatened seashores incorporates locations that will be submerged by more than 100 metres, 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 metres, especially near human settlements and in small islands, such as the Caribbean and the Mediterranean.
Large beaches will narrow by 100-200 metres on Atlantic and Pacific coasts and the Australian side of the Indian Ocean, wiping out more than 60% of sand deposits in a number of developing countries that are economically fragile and heavily dependent on coastal tourism.
But swift action to limit emissions and fight climate breakdown could help reduce the impact, experts say. Moderate emissions mitigation could prevent 17% of the shoreline retreat in 2050 and 40% in 2100, thus preserving on average 42 metres of sand between land and sea, Vousdoukas said.