Marcan Graffin, Vincent Regard, Sébastien Carretier, Pierre Maffre, Rafael Almar

The current retreat of the world's coastline has a profound impact on human activities and ecosystems. The scientific community has primarily focused on the potential impact of sea level rise. At the global scale, the contribution of river sand loads to coastal erosion has been overlooked. Here we present the first global sand pathway model from land to sea. Our model reveals that sand tends to accumulate towards tropical regions. We show that the recent shoreline evolution is significantly controlled by the imbalance in the sand budget, challenging the idea that sea level rise due to climate change is currently the main driver of coastal erosion. Our model highlights that the significant reduction in sand supply due to tens of thousands of river dams and its consequences on coastal erosion could be avoided by an effective sustainable management policy.