Green mangrove forests along a river in Brazil. — Mangrove forests can absorb even more carbon dioxide than scientists previously thought. This is shown in Alex Cabral's doctoral thesis at the Department of Marine Sciences, University of Gothenburg.

Photo: Alex Cabral

Mangroves more important to Earth's climate than previously known

Published

5 September 2024

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New research reveals that mangrove forests play an even more crucial role in capturing and storing carbon than scientists previously understood. Therefore, protection of these important coastal vegetated areas is needed to mitigate climate change.
“The global importance of mangroves impacts us all. Understanding how they function, and supporting conservation and restauration efforts, is crucial for a sustainable future,” says Alex Cabral, doctoral student at the Department of Marine Sciences, University of Gothenburg.

Researchers have known that mangroves absorb more carbon per square meter than any terrestrial forest type in the world, and that they are extremely important in mitigating global warming and its effects.

A doctoral thesis from the University of Gothenburg now shows that mangrove forests are even better: not only do they capture carbon from the atmosphere and store it in their muddy anoxic soil, but they also send a lot of it out to ocean as a type of dissolved carbon.

Alex Cabral with water samples for later analysis in Sweden. The researchers lived on boats inside the mangrove forest creeks. Alex Cabral then used kayaks to transport equipment to and from measurement areas.

Fluxes previously overlooked

Most previous research has overlooked these fluxes of mangrove-derived carbon to the ocean. In his PhD thesis, Alex Cabral demonstrates that this carbon reaches the continental shelves, where it can be exported to the global oceans and stored for thousands of years.

“This means that mangroves can absorb even more carbon than we previously believed,” says Alex Cabral, doctoral student at the Department of Marine Sciences, University of Gothenburg, and author of the study.

“I also found that global mangroves effectively capture nitrous oxide, a greenhouse gas significantly more potent than carbon dioxide and methane in trapping heat in the atmosphere. As a result, the combined carbon and nitrous oxide sink in mangroves significantly contributes to climate change mitigation,” says Alex Cabral.

Better protection efforts needed

Mangroves are unique trees that grow in salt water along the coasts of tropical and subtropical regions, forming vital coastal ecosystems. However, mangrove forests are vulnerable to threats primary stemming from human activities: coastal development, pollution, and deforestation for aquaculture.

Nearly half of the world's mangrove forests are at risk of collapse by 2050, according to a new assessment by the International Union for Conservation of Nature (IUCN). Therefore, protection and conservation efforts are essential. The loss of mangroves has severe consequences, including increased vulnerability to natural disasters, loss of livelihoods, reduced biodiversity, and accelerated climate change.

Alex Cabral in muddy soil taking samples — The mangrove forests are warm, and research is full of practical challenges. The air is full of mosquitoes, the soil is soft and muddy with large roots and full of crabs. The crabs often try to invade the equipment and even crawl up on the researchers.

“Quantifying the carbon absorption potential of mangroves and analyzing their impact on the atmosphere and ocean can lead to better protection of these crucial ecosystems. This knowledge empowers us to develop more effective climate change strategies and extend protection to other vital coastal vegetated habitats like saltmarshes and seagrass meadows,” says Alex Cabral.

Writer: Annika Wall