Sea-level rise is impacting the longest undeveloped stretch of coastline in the contiguous United States: The Florida Big Bend. Due to its low elevation and a higher-than-global-average local rate of sea-level rise, the region is losing coastal forest to encroaching marsh at an unprecedented rate. Previous research found a rate of forest-to-marsh conversion of up to 1.2 km² year⁻¹ during the nineteenth and twentieth centuries, but these studies evaluated small-scale changes, suffered from data gaps, or are substantially outdated. We replicated and updated these studies with Landsat satellite imagery covering the entire Big Bend region from 2003 to 2016 and corroborated results with in situ landscape photography and high-resolution aerial imagery. Our analysis of satellite and aerial images from 2003 to 2016 indicates a rate of approximately 10 km² year⁻¹ representing an increase of over 800%. Areas previously found to be unaffected by the decline are now in rapid retreat.

海平面上升正在影响美国毗连最长的未开发海岸线：佛罗里达大弯。由于其低海拔和高于全球平均水平的当地海平面上升速度，该地区正以前所未有的速度将沿海森林流失到不断侵占的沼泽地。先前的研究发现森林到沼泽的转化率高达 1.2 公里² 年^-1在 19 世纪和 20 世纪，但这些研究评估了小规模的变化，存在数据缺口，或者已经过时。我们使用覆盖整个大弯地区 2003 年至 2016 年的 Landsat 卫星图像复制和更新了这些研究，并通过原位景观摄影和高分辨率航空图像证实了结果。我们对 2003 年至 2016 年的卫星和航拍图像的分析表明，速度约为 10 km ²  year ^-1，增长了 800% 以上。以前发现不受下降影响的地区现在正在迅速撤退。