This study calls upon recently discovered aerial photographs for two atolls in the Indian Ocean Chagos Archipelago. Pairing these vintage data with modern satellite imagery allows the coastline dynamics of a suite of islands to be quantified over a 36-to-50-yr. period. Peros Banhos represents one of the few atolls globally where natural island dynamics can be appraised; withstanding just one of its 35 islands, this atoll has never been settled by humans. By contrast, Diego Garcia has undergone pronounced anthropogenic change in the last fifty years. Statistics bring new insights to the persistence of these atoll islands under the contemporary conditions of sea level rise. Key findings include: (i) Coastlines facing the prevailing trade winds retreat through time, while those in leeward positions expand; (ii) coastline expansion and retreat are in balance such that total land area of all the considered islands is virtually static over the last 50 years; and, (iii) small islands (<20 ha) are substantially more dynamic than large ones. The stretches of the Diego Garcia coastline in close vicinity to human modification are more likely to suffer erosion than those situated far from human activity, and also substantially more likely to erode, than those of the uninhabited islands of Peros Banhos. A comparison between the behavior of a broad portfolio of islands spanning the Indian and Pacific Oceans emphasizes local factors such as wind direction, to be better determinants of coastline dynamics than global factors, such as the rate of eustatic sea-level rise. In aggregate, our data suggest that atoll islands are likely to persist in the face of accelerating sea-level rise over the next decades, but their high rate of coastline dynamics will challenge human habitability.

这项研究呼吁在印度洋查戈斯群岛上最近发现的两个环礁的航拍照片。将这些老式数据与现代卫星图像结合使用，可以量化36至50年内一组岛屿的海岸线动态。时期。佩罗斯·班纽斯（Peros Banhos）是全球少数几个可以评估自然岛屿动态的环礁之一；尽管只有35个岛屿中的一个，但这个环礁却从未有人为之定居。相比之下，迭戈·加西亚（Diego Garcia）在过去的50年中发生了明显的人为变化。统计数字为当代海平面上升条件下这些环礁岛的持续性提供了新的见解。主要发现包括：（i）面对盛行贸易风的海岸线随着时间的流逝而退缩，而背风位置的海岸线则在扩大；（ii）海岸线的扩张和撤退是平衡的，因此在过去的50年中，所有被考虑的岛屿的总土地面积实际上是静止的；（iii）小岛（<20公顷）比大岛更具活力。与没有人类活动的地区相比，紧邻人类改造的迭戈加西亚（Diego Garcia）海岸线更容易遭受侵蚀，并且比无人居住的佩罗斯·班纽斯（Peros Banhos）岛屿遭受侵蚀的可能性更大。对横跨印度洋和太平洋的众多岛屿的行为进行比较，强调了风向等局部因素，而不是全球性因素（如海平面欣欣向荣的上升速度），是海岸线动态的更好决定因素。合计，