Climate-induced sea-level rise and vertical land movements, including natural and human-induced subsidence in sedimentary coastal lowlands, combine to change relative sea levels around the world’s coasts. Although this affects local rates of sea-level rise, assessments of the coastal impacts of subsidence are lacking on a global scale. Here, we quantify global-mean relative sea-level rise to be 2.6 mm yr⁻¹ over the past two decades. However, as coastal inhabitants are preferentially located in subsiding locations, they experience an average relative sea-level rise up to four times faster at 7.8 to 9.9 mm yr⁻¹. These results indicate that the impacts and adaptation needs are much higher than reported global sea-level rise measurements suggest. In particular, human-induced subsidence in and surrounding coastal cities can be rapidly reduced with appropriate policy for groundwater utilization and drainage. Such policy would offer substantial and rapid benefits to reduce growth of coastal flood exposure due to relative sea-level rise.

气候引起的海平面上升和垂直陆地运动，包括沿海沉积低地的自然和人为沉降，共同改变了世界沿海地区的相对海平面。尽管这会影响当地的海平面上升速度，但在全球范围内仍缺乏对沉降对海岸影响的评估。在这里，我们将过去二十年的全球平均相对海平面上升量化为 2.6 mm yr ^{-1 。}然而，由于沿海居民优先位于下沉位置，他们的平均相对海平面上升速度高达 4 倍，为 7.8 至 9.9 毫米^-1. 这些结果表明，影响和适应需求远高于报告的全球海平面上升测量结果。特别是，通过适当的地下水利用和排水政策，可以迅速减少沿海城市及其周边地区的人为沉降。这种政策将提供大量和快速的好处，以减少由于相对海平面上升而导致的沿海洪水风险的增长。