Excerpt:
Mangrove forests have been protecting coastlines around the world against erosion and storm surges for millennia. But in 2020, the residents on many islands in the Maldives noticed that many of their mangrove forests were starting to die off. Where once these forests had been lush, now they were turning brown and lifeless.

Our team of scientists has worked closely with coastal communities in the Maldives to investigate that 2020 phenomenon. In our new study, we highlight how mangrove die-off events like this have big implications not just for the Maldives, but also for other island nations and coastal ecosystems around the world.

Mangroves are remarkable trees and shrubs that grow along tropical and subtropical coastlines of more than 120 countries and territories.

Mangroves are carbon powerhouses, storing three to five times more carbon per equivalent area than tropical rainforests. They’re biodiversity hotspots and crucial fish nurseries. For many coastal communities, especially in developing nations, mangroves are essential for food security and livelihoods by providing important protein sources like prawns, crabs and fish.

Mangroves act as natural storm barriers, protecting coastlines from erosion and flooding. For island nations like the Maldives, mangroves are a vital defence against rising seas and storms. So, when over 25% of the Maldives’ mangrove-containing islands died off in 2020, local residents became seriously concerned. Using satellite imagery, we found that some islands lost more than half their mangrove cover.

To investigate potential causes, we examined the wood from affected mangroves. The chemical makeup of mangrove wood can reveal if the trees were struggling with too much salt. Our tests showed that the dead mangroves had been under significant salt stress, meaning they were drowning in saltwater.

Mangroves can typically keep pace with gradually rising seas by building up their own sediment. But when sea levels rise too quickly, and mangroves experience salt stress, this defence mechanism can’t keep up.

Sure enough, our research points to the culprit as being rapidly rising sea levels, supercharged by climate change. The Maldives is the world’s lowest-lying country, with an average elevation of just 1.5m above sea level. This makes it acutely vulnerable to rising sea levels…