Strong national and regional changes in the accessibility of the world’s coral reefs over the last two decades

<h2>Summary</h2> Human pressure on global ecosystems is strongly mediated by how accessible they are, yet we know little about accessibility changes worldwide. Here, we quantify the changing accessibility of global coral reefs, an entire ecosystem, to the nearest human settlement and nearest markets between 2001 and 2023. Our study reveals that the small changes in average coral reef accessibility mask the substantial shifts occurring at the national and regional scales. Decreasing accessibility is related to coastal vegetation restoration blocking access, while increasing accessibility is predominantly due to the expansion of rural settlements. We also highlight that coral reefs in marine protected areas tend to be slightly less accessible, but as travel time in surrounding areas increases, protected areas may face growing pressure. Our results provide insights into how the accessibility of the world's coral reefs is changing and highlight what that may mean for their protection.