More than 1,000 small islands in the tropics might become uninhabitable by mid-century due to rising sea levels, much sooner than previously estimated, according to a new study in Science Advances.
The study, funded by the US military, accelerates prior research that estimated the many atoll islands to become uninhabitable by the end of the century at least.
Sea levels are rising, with the highest rates in the tropics, where thousands of low-lying coral atoll islands are located. Most studies on the resilience of these islands to sea-level rise have projected that they will experience minimal inundation impacts until at least the end of the 21st century.
The new research warns that these studies have not taken into account the additional hazard of wave-driven overwash or its impact on freshwater availability. It projects the impact of sea-level rise and wave-driven flooding on atoll infrastructure and freshwater availability under a variety of climate change scenarios. These projections indicate that, on the basis of current greenhouse gas emission rates, that most atoll islands will suffer annual wave-driven overwash by the mid-21st century.
This annual flooding will result in the islands becoming uninhabitable because of frequent damage to infrastructure and the inability of their freshwater aquifers to recover between overwash events.
Crucially, islands like the Maldives and Marshalls will become uninhabitable even if sea levels rise according to the most optimistic roadmaps outlined in plans like the Paris Agreement, which seeks to limit warming to below 2℃ by reducing carbon emissions. Even if that plan is successful, many hundreds of islands will become uninhabitable, and hundreds of thousands of people will become climate refugees.