With the COP30 summit continuing to seek an agreement on the future of the climate fight there are warnings that once rare tidal events are set to put low lying islands under increasing threat.

In the summer of 2022, 20 islands in the Maldives were flooded when a distant swell event in the Indian Ocean coincided with an extremely high tide level.

A new analysis of the incident, compiled using fieldwork and computer modelling, has shown it to be a relatively rare occurrence with the worst flooding seen in the region since the Boxing Day tsunami of 2004.

However, scientists have warned that future predicted rises in sea levels, potentially coupled with an increase in extreme weather events and wave conditions, could result in such flooding becoming far more common, perhaps happening every two to three years by around 2050.

It has led them to call on authorities in the Maldives, and other low-lying island nations, to urgently identify, evaluate and implement adaptation strategies to mitigate against the adverse impacts of flooding without delay.

The research was carried out by researchers from the University of Plymouth and Deltares, a not-for-profit applied research institute in the Netherlands, as part of the ARISE project, a programme supported by UK Research and Innovation.

Professor Gerd Masselink, professor of Coastal Geomorphology at the University of Plymouth and leader of the ARISE project, said: “Low-lying atoll islands are among the most vulnerable places on Earth due to rising sea levels and, when they flood, it is disruptive and potentially hazardous. Global computer modelling studies suggest that by 2050 what used to be rare, extreme floods – like those experienced in the Maldives in 2022 – could happen every year in tropical regions.

“However, our research has also shown how waves washing over an island can deposit coral sand and rubble onto the island’s surface, raising its elevation and potentially making it more resilient to future flooding events and sea-level rise. It is a complex picture and, for people living in these communities and the infrastructure protecting them, is an area that needs to be studied further.”

The study is the latest led by scientists in Plymouth to explore the effect of rising sea levels and other climate related events on atoll nations in the Indian Ocean and the Pacific Ocean.

Previous research has suggested that despite the nations being extremely vulnerable to the effects of climate change, island ‘drowning’ might not be inevitable as atoll islands without significant coastal protection structures, such as seawalls, could naturally adapt and survive.

Dr Robert McCall, a coastal flooding specialist at Deltares and one of the co-authors of the study, said: “Low-lying atoll island nations are clearly going to face increasing risk of coastal flooding as sea levels rise. Research such as this allows us to support governments and other decision-makers to plan for the future, by quantifying when, where, and by how much, the risk of flooding will increase. Importantly, we can also use our understanding of the processes leading to flooding to support the selection and design of flood protection, mitigation, and adaptation solutions, helping societies to manage future flood risk.”