Rubble islands are dynamic sedimentary features present on reef platforms that evolve under a variety of morphodynamic processes and controlling mechanisms. They provide valuable inhabitable land for small island nations, critical habitat for numerous species, and are threatened by climate change. Aiming to investigate the controlling mechanisms dictating the evolution of One Tree Island (OTI), a rubble island in the Southern Great Barrier Reef, we combined different remotely-sensed data across varying timescales with wave data extracted from satellite altimetry and cyclone activity. Our findings show that (1) OTI had expanded by 7% between 1978 and 2019, (2) significant gross planform decadal adjustments were governed by the amount, intensity, proximity, and relative position of cyclones as well as El Niño Southern Oscillation (ENSO) phases, and (3) the mechanisms of island growth involve rubble spits delivering and redistributing rubble to the island through alongshore sediment transport and wave overtopping. Frequent short-term monitoring of the island and further research coupling variations in the different factors driving island change (i.e., sediment availability, reef-wave interactions, and extreme events) are needed to shed light on the future trajectory of OTI and other rubble islands under a climate change scenario.

Coral reef islands can support large legal maritime zones (i.e. ocean spaces where States have rights and responsibilities) and are of international and geopolitical importance. This review focuses on low-lying coral reef islands supplied with sediments derived from skeletons and shells of calcifying organisms. For coral islands, the outer ‘low-water line’ of the reef can be used as the legal ‘baseline’ to establish maritime zones. Coral islands and the reefs that support them are experiencing the effects of rising and warming seas, increased storminess and ocean acidification. Coral reefs, their islands and associated maritime zones support millions of people, including those in Small Island Developing States (SIDS). SIDS communities are arguably the least responsible for climate change but are at the forefront of its impacts so ensuring their continued wellbeing is a global responsibility. Securing the future of coral reefs and islands is dependent on reducing global climate threats and emissions, improving local management, and investing in restoration and adaption research. It is uncertain if coral islands will persist into the future, and on what timelines. This raises questions such as, where coral islands support maritime zones, what are the legal implications of island instability or loss? This review focuses on the bio-physical interactions of coral islands and associated reefs in the face of changing climates, and implications for legal maritime zones and SIDS.

Coral reefs protect coastlines from inundation and flooding and serve over 200 million people globally. Wave transformation has previously been studied on coral reef flats with limited focus on forereef zones where wave transformation is greatest during high‐energy conditions. This study investigates the role of forereef spur and groove (SaG) morphology in wave energy dissipation and transmission at the reef crest. Using XBeach on LiDAR‐derived bathymetry from One Tree Island in the southern Great Barrier Reef, we reproduced dissipation rates comparable to SaG field studies. We examined how wave energy dissipation differs between realistic bathymetry and those with SaG features removed, demonstrating an up to 40% decrease in dissipation when SaG features are absent. We then investigated changes to wave energy dissipation and wave transmission at the reef crest based on IPCC AR5 emission scenarios (RCP2.6 and RCP8.5) and a total disaster scenario (TD) for the year 2100. For RCP2.6, an increase in wave heights of 0.8 m and an increase in water level of 0.3 m resulted in a two‐fold increase in dissipation rates. For RCP8.5 and TD, with no increase in incident wave height, dissipation rates were 29% and 395% lower than RCP2.6. This resulted in increased wave transmission at the reef crest by 1.8 and 2.7 m for the RCP8.5‐ and TD based models, respectively, when compared to the RCP2.6‐based model. The results from our novel modeling approach of using long‐shore varying accurate bathymetry on forereefs show increased wave energy dissipation rates with implications for reducing coastal flooding and island inundation on reef‐lined coasts.