Sandy beaches occupy more than one-third of the global coastline¹ and have high socioeconomic value related to recreation, tourism and ecosystem services². Beaches are the interface between land and ocean, providing coastal protection from marine storms and cyclones³. However the presence of sandy beaches cannot be taken for granted, as they are under constant change, driven by meteorological^4,5, geological⁶ and anthropogenic factors^1,7. A substantial proportion of the world’s sandy coastline is already eroding^1,7, a situation that could be exacerbated by climate change^8,9. Here, we show that ambient trends in shoreline dynamics, combined with coastal recession driven by sea level rise, could result in the near extinction of almost half of the world’s sandy beaches by the end of the century. Moderate GHG emission mitigation could prevent 40% of shoreline retreat. Projected shoreline dynamics are dominated by sea level rise for the majority of sandy beaches, but in certain regions the erosive trend is counteracted by accretive ambient shoreline changes; for example, in the Amazon, East and Southeast Asia and the north tropical Pacific. A substantial proportion of the threatened sandy shorelines are in densely populated areas, underlining the need for the design and implementation of effective adaptive measures.

沙滩占全球海岸线¹的三分之一以上，并具有与娱乐，旅游和生态系统服务²相关的高社会经济价值。海滩是陆地和海洋之间的界面，为海上风暴和飓风³提供海岸保护。然而，沙滩的存在不能被认为是理所当然的，因为它们在不断变化，受到气象学^4,5，地质学⁶和人为因素^1,7的驱动。世界上大部分的沙质海岸线已经在侵蚀^1,7，这种情况可能会因气候变化而恶化^8,9。在这里，我们表明，海岸线动态的环境趋势，再加上海平面上升导致的沿海衰退，可能导致到本世纪末世界近一半的沙滩濒临灭绝。适度减少温室气体排放可以防止40％的海岸线撤退。在大多数沙滩上，预计的海岸线动态主要由海平面上升决定，但是在某些地区，侵蚀性趋势被环境海岸线上不断增加的变化所抵消。例如，在亚马逊，东亚和东南亚以及北部热带太平洋。很大一部分受威胁的沙质海岸线位于人口稠密的地区，突显了设计和实施有效适应措施的必要性。