Paris: Climate change and sea level rise are currently on track to wipe out half the world's sandy beaches by 2100, researchers warned Monday.
Even if humanity sharply reduces the fossil fuel pollution that drives global warming, more than a third of the planet's sandy shorelines could disappear by then, crippling coastal tourism in countries large and small, they reported in the journal Nature Climate Change.
"Apart from tourism, sandy beaches often act as the first line of defence from coastal storms and flooding, and without them impacts of extreme weather events will probably be higher," lead author Michalis Vousdoukas, a researcher at the European Commission's Joint Research Centre, told AFP.
"We have to prepare."
Some countries, such as the United States, are already planning extensive defence systems, but in most nations such massive engineering schemes will not be unfeasible, unaffordable or both.
Australia could be hit hardest, according to the findings, with nearly 15,000 kilometres (more than 9,000 miles) of white-beach coastline washed away over the next 80 years, followed by Canada, Chile and the United States.
The 10 countries that stand to lose the most sandy shoreline also include Mexico, China, Russia, Argentina, India and Brazil.
Sandy beaches occupy more than a third of the global coastline, often in highly populated areas.
But new construction, sea level rise, storm surge from hurricanes or typhoons, and reduced sediment from dammed rivers are all eroding these shorelines, threatening livelihoods and infrastructure.
To assess how quickly and by how much beaches might disappear, Vousdoukas and colleagues plotted trend lines across three decades of satellite imagery dating back to 1984.
From there, they projected future erosion under two climate change scenarios.
The "worst case" RCP8.5 pathway assumes carbon emissions will continue unabated, or that Earth itself will begin to boost atmospheric greenhouse gas concentrations -- from, for example, permafrost -- independent of human action.