DECADAL EVOLUTION OF CORAL ISLANDS IN A CHANGING OCEAN AND CLIMATE

Abstract

Coral reef islands are under threat from warming and rising seas, ocean acidification and increased storminess. Coral islands are low-lying accumulations of sediment derived from the shells and skeletons of calcifying reef organisms. IPCC predications and COP26 highlight that the future of coral islands is not certain as islands are morphologically active. It is unclear what tipping points are causing negative impacts on some coral reef islands and not others. A better understanding of island stability and vulnerability is urgently needed. This has direct implications for over 200 million people that rely on reefs and their islands for their livelihoods (Ferrario et al., 2014). Further, coastal States such as Australia, USA, the Philippines and Small Island Developing States (SIDS) use coral reef islands as legal baselines to support their maritime jurisdictions (UNCLOS, 1982). We focus on 31 of Australia’s offshore coral reef islands on 10 reefs across the Coral Sea and NW Shelf. These islands are environmentally and geo-politically important as they support and extend Australia’s maritime jurisdiction. Island morphology (e.g., shoreline positions, areas, shapes) in historical aerial and satellite imagery (1977-now) were compared to ocean and climate data (e.g., storm tracks, NOAA Coral Watch). We used this data to identity tipping points that drive decadal changes in coral reef island stability.