Effects of Environmental and Climatic Changes on Coral Reef Islands

Coral reef islands are low-lying, wave-deposited sedimentary landforms. Using an eco-morphodynamic framework, this review examines the sensitivity of islands to climatic and environmental change. Reef island formation and morphological dynamics are directly controlled by nearshore wave processes and ecologically mediated sediment supply. The review highlights that reef islands are intrinsically dynamic landforms, able to adjust their morphology (size, shape, and location) on reef surfaces in response to changes in these processes. A suite of ecological and oceanographic processes also indirectly impact hydrodynamic and sediment processes and thereby regulate morphological change, though the temporal scales and magnitudes of impacts on islands vary, leading to divergent morphodynamic outcomes. Climatic change will modify the direct and indirect processes, causing complex positive and negative outcomes on islands. Understanding this complexity is critical to improve predictive capabilities for island physical change and resolve the timescales of change and lag times for impacts to be expressed in island systems.