More than half the world’s mangroves are at risk of collapse by 2050 in the face of sea level rise and worsening coastal storms, the first assessment of its kind has found.
The International Union for the Conservation of Nature (IUCN) assessed mangrove ecosystems across the world using its Red List global standard for assessing the health of different habitats.
Mangroves are key habitats, storing almost 11 billion tonnes of carbon, providing nurseries and homes for important fish stocks and a host of other wildlife, and protecting 15.4 million people and $65 billion worth of property a year from coastal disasters such as storms and flooding.
They cover around 150,000 square kilometres along mostly tropical, sub-tropical and some warm temperate coasts of the world, with around 15% of coastlines globally covered by mangroves, the IUCN said.
The assessment, the first to look at one type of ecosystem across the planet, shows 50% of the world’s mangrove ecosystems are at risk of collapse, classed as vulnerable, endangered or critically endangered.
Deforestation and development
Nearly a fifth of the mangroves that were assessed (19.6%) are at severe risk of collapse, classed as being endangered or critically endangered.
Mangroves in two regions, one covering the US south coast and eastern Mexico and another covering South India and Sri Lanka, and the Maldives, are critically endangered, it said.
Conservation experts said mangroves were threatened by deforestation, development, pollution and dam construction, but the risks to the ecosystems were increasing due to sea level rise and a greater frequency of severe coastal storms associated with climate change.
Climate change is described as a “recent and growing threat”, which threatens one third (33%) of the mangrove ecosystems assessed, through sea level rise and increased frequency and intensity of cyclones, typhoons, hurricanes and storms.
Maintaining mangroves would be key to tackling the impacts of climate change, with healthy habitats better able to cope with sea level rise and offering inland protection from the impacts of storms, the IUCN said.
Carbon storage and sequestration
Angela Andrade, chairwoman of the IUCN commission on ecosystem management, said: “Mangrove ecosystems are exceptional in their ability to provide essential services to people, including coastal disaster risk reduction, carbon storage and sequestration, and support for fisheries.
“Their loss stands to be disastrous for nature and people across the globe. That is why this assessment is so important.”
Dr Grethel Aguilar, IUCN director-general, said: “The first global assessment of mangrove ecosystems gives key guidance that highlights the urgent need for co-ordinated conservation of mangroves – crucial habitats for millions in vulnerable communities worldwide.
“The assessment’s findings will help us work together to restore the mangrove forests that we have lost and protect the ones we still have.”
It is the first global assessment of a full ecosystem group across the planet using the Red List of ecosystems, IUCN said.
