Future climatic change and sea-level rise threaten the persistence of reef islands potentially making them uninhabitable over the next century. Improved understanding of island morphodynamics at multiple time scales is required for resolving major drivers of shoreline change and predicting future island resilience. Utilising 45 individually mapped shorelines, the morphodynamic change of a shelf-edge reef island (Raine Island, Great Barrier Reef) has been quantified over a 57-year time scale in the context of environmental change and anthropogenic impacts. Results show that between 1963 and 2020, there has been an average net shoreline movement (NSM) of −4.71 m and an average rate of retreat of −0.11 m/yr. However, only 23% of the shoreline has exhibited statistically significant erosion while the remaining 77% has remained stable. Importantly, data reveal a remarkable level of long-term shoreline stability despite large seasonal fluctuations in wind and wave climate, episodic storm events, and a regional sea level rise currently outpacing the global mean. Direct human impact, through modifications of the beach profile since 2014, have resulted in localised increases in rates of shoreline change but have only slightly decreased the proportion of stable shoreline (91% since modifications commenced versus 96% prior to modifications). Interestingly, there is a significant decreasing trend in island planform area over the 57-year period and especially over the last decade. However, the length of the observation interval between sampled shorelines has a strong effect on the change in planform area recorded over the interval, suggesting increased sampling frequency, rather than sea level rise, is a more likely cause of the decreasing trend. The findings of this study have direct implications for more accurate assessments of past, present and future shoreline change on reef islands. They also support the concept of 21st century island persistence in the face of climate change although the relative resilience of a given island to change (e.g., sea level, human modifications) will depend on a continuous adequate supply of sediment from organisms living on the surrounding reef, which may or may not be threatened in the future.

未来的气候变化和海平面上升威胁到礁岛的持久性，可能使它们在下个世纪无法居住。为了解决海岸线变化的主要驱动因素和预测未来岛屿的恢复力，需要在多个时间尺度上更好地了解岛屿形态动力学。利用 45 条单独绘制的海岸线，在环境变化和人为影响的背景下，一个大陆架边缘礁岛（雷恩岛、大堡礁）的形态动力学变化在 57 年的时间尺度上进行了量化。结果表明，1963 年至 2020 年之间，平均净海岸线移动 (NSM) 为 -4.71 m，平均后退率为 -0.11 m/yr。然而，只有 23% 的海岸线出现了统计上显着的侵蚀，而其余 77% 的海岸线保持稳定。重要的，数据显示，尽管风浪气候季节性波动较大，风暴事件频发，区域海平面上升目前超过全球平均水平，但海岸线的长期稳定性水平显着。自 2014 年以来，通过修改海滩剖面，人类的直接影响导致海岸线变化率局部增加，但仅略微降低了稳定海岸线的比例（自修改开始后为 91%，修改前为 96%）。有趣的是，57 年间，尤其是近 10 年间，岛屿地貌面积呈显着下降趋势。然而，采样海岸线之间的观测间隔长度对间隔内记录的平面面积变化有很大影响，这表明采样频率增加，而不是海平面上升，是下降趋势的一个更可能的原因。这项研究的结果对更准确地评估礁岛过去、现在和未来的海岸线变化具有直接意义。他们还支持面对气候变化的 21 世纪岛屿持续存在的概念，尽管一个特定岛屿对变化（例如海平面、人类改变）的相对恢复力将取决于生活在周围的生物体持续充足的沉积物供应珊瑚礁，未来可能会或可能不会受到威胁。