Loss of marine and coastal biodiversity and ecosystem services is a key risk in small islands . Coral bleaching caused by elevated water temperatures is the most visible and widespread manifestation of a climate change impact on coastal ecosystems in most small islands but is far from being the only one . Severe coral bleaching, together with declines in coral abundance have been documented in many small islands, especially those in the Pacific Ocean and Indian Ocean  . During severe bleaching events, not only do reefs lose a significant amount of live coral cover, but they also experience a decrease in growth potential, and thus reef erosion surpasses reef accretion . Median return time between two severe bleaching events has diminished steadily since 1980 and is now only 6 years  and is often associated with warm phase of ENSO events  . Modelling of both bleaching and ocean acidification effects under future climate scenarios suggested that some Pacific small islands  will experience conditions that cause severe bleaching on an annual basis before 2040 and that 90% of the world reefs are projected to experience conditions that result in severe bleaching annually by 2055  . Models are currently predicting the large-scale loss of coral reefs by mid-century under even low-emission scenarios. Even achieving emission reduction targets consistent with the ambitious goal of 1.5℃ of global warming under the Paris Agreement will result in the further loss of 70-90% of reef-building corals compared to today, with 99% of corals being lost under warming of 2ºC or more above the pre-industrial period  .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report