AUSTRALIA - FEBRUARY 25: Mangrove shoots grow in the shallows of the Mossman River, Daintree, Australia. (Photo by Tim Graham/Getty Images)

Tim Graham/Getty Images

Mangrove swamps have a multi-faceted role, when it comes to the Earth’s eco-system, but they are also not immune to the impacts of climate change.

They can play a central role as wildlife havens, carbon stores, storm defences, and ocean purifiers.

But recent reports have highlighted how they could be impacted by rising temperatures and the other roles they play in maintaining the planet.

A new study by researchers, led by the University of Exeter with partners in Colombia and the U.S, claims sea-level rises will initially trigger more carbon accumulation in some locations, but will reduce carbon storage in the forests over the long term.

Previous research has suggested rising seas could increase carbon storage in mangroves, but the new study challenges this.

Mangroves are made up of salt-tolerant plants, which grow in coastal areas.

They cover less than 1% of Earth’s surface but store about 15% of all ocean carbon, most of it in their soils.

The findings show that, while carbon storage might increase in localised spots as sea levels rise, storage at the scale of whole forests is likely to decline over the next 100 years.

Dr. Arya Iwantoro, who carried out the research at the University of Exeter, but is now based at the University of Plymouth, said mangrove forests are crucial for slowing climate change, in a statement.

Dr. Iwantoro added research about carbon storage in mangroves is usually based on field observations, and such studies have found that carbon storage can increase as sea levels rise.

He added in order to investigate this, researchers developed a new model that links water flow and sediment transport, mangrove growth and dieback, and carbon storage while keeping track of changes in the composition of muddy beds where mangroves grow.

The WWF’s coastal ecosystem restoration senior specialist, Dr. Lanie Esch said mangroves are one of nature's greatest allies in the fight against biodiversity loss and climate change, in an interview.

Dr. Esch added protecting mangroves is probably one of the “smartest investments we can make for people, nature, and the climate”.

“Mangroves live in carbon-rich soil. Their complex root systems capture and accumulate sediment and organic matter, making them powerful carbon stores that often outperform tropical forests,” she told me.

“Their underwater forest root systems are really great at stabilizing sediments and providing protection to marine wildlife, and in this way, they can act as nurseries for many fisheries, supporting the livelihoods of the surrounding local communities.”

And Tess Geers, a senior research director at the marine conservation group, Oceana, said mangroves are not immune to climate change, in an email.

Geers added the report demonstrates why it is hard to predict exactly how species and ecosystems will respond to the climate crisis.

“Studies like these are necessary to help us understand the potential consequences of inaction, but we already know that mangroves and other coastal habitats can be one of Earth’s biggest assets in fighting the climate crisis,” she added.

“They play a vital role in capturing and storing carbon and providing natural protection to coastal communities against more frequent and severe storms. But they can only take so much.

“World leaders must act now to protect mangroves and other coastal ecosystems, while also rapidly reducing emissions,” said Geers.

A recent study by the Department of Earth and Environmental Sciences at the Chinese University of Hong Kong (CUHK) also revealed that mangroves are also highly efficient when it comes to the removing nitrogen pollution.

The study has found that although mangroves cover less than 0.1% of the world’s land area, they remove up to 870,000 tonnes of nitrogen pollutants from coastal waters each year.

According to the report, the annual ecological value of this nitrogen purification service is worth more than US$8.5 billion.