More than half of the world's mangrove ecosystems are at risk of collapse, with nearly one in five facing severe risk, according to the findings of the first global mangrove assessment.

Climate change threatens one-third (33 per cent) of the mangrove ecosystems, according to the study done using the International Union for Conservation of Nature's (IUCN) Red List of Ecosystems -- a global standard for measuring the health of ecosystems.

Deforestation, development, pollution and dam construction pose a serious threat to mangroves, but the risk to these ecosystems is increasing due to sea-level rise and the increased frequency of severe storms due to climate change.

"IUCN's Red List of Ecosystems is key to tracking progress towards the goal of halting and reversing biodiversity loss, in line with the Kunming-Montreal Global Biodiversity Framework. The first global assessment of mangrove ecosystems gives key guidance that highlights the urgent need for coordinated 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," Grethel Aguilar, IUCN Director General, said.

This study classified the world's mangrove ecosystems in 36 different regions called provinces and assessed the threats and risk of collapse in each region.

IUCN led the work with active involvement of more than 250 experts in 44 countries.

"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," Angela Andrade, Chair of IUCN Commission on Ecosystem Management, said.

The findings show climate change and sea-level rise will result in the loss of 1.8 billion tonnes of carbon stored (16 per cent of the total current carbon stored in mangroves) by 2050, currently valued at least USD 13 billion at market prices in voluntary carbon markets.

"Climate change is a recent and growing threat to mangrove ecosystems, especially their exposure to more frequent and severe weather events, and sea-level rise. Increased frequency and intensity of cyclones/typhoons/hurricanes and tropical storms impact mangroves on some coastlines," the IUCN assessment report read.

One-third of the world's mangrove ecosystem provinces will be severely affected by sea-level rise, with 25 per cent of the global mangrove area predicted to be submerged in the next 50 years.

The Northwest Atlantic, North Indian Ocean, Red Sea, South China Sea, and Gulf of Aden coasts are expected to be particularly severely affected, it said.

Mangroves store around 11 billion tonnes of carbon, which is almost three times the amount of carbon stored by tropical forests of the same size.

These ecosystems protect 15.4 million people and USD 65 billion worth of property per year from coastal disasters. In 2050, this could rise to 15.5 million and USD 118 billion because of population growth and rise in property values.

The assessment finds that maintaining mangrove ecosystems across the globe will be key for mitigating the impacts of climate change, with healthy mangroves able to better cope with sea level rise and offering inland protection from the impacts of hurricanes, typhoons and cyclones.