Mangroves and Coral Reefs Provide Vital Natural Defense Against Extreme Weather and Climate Change; Protect 8.5+ Million Highly Vulnerable People

May 29, 2020

Preserving Blue Carbon Ecosystems is a win-win-win for climate, resilience and social outcomes

Arlington, VA (May 29, 2020) – As extreme weather season ramps up, a study released today underscores the importance of mangroves and coral reefs when it comes to protecting vulnerable coastal communities from extreme winds and storm surges – both today and even more so in the future as climate change progresses.

Published in the scientific journal PLOS ONE, the paper was co-authored by three Conservation International scientists – Dave Hole, Will Turner and Mariano Gonzalez-Roglich.

The study found that around 31 million people live in regions “highly vulnerable” to sea-level rise and hurricanes or tropical cyclones, the impacts of which are intensifying due to climate change. Of those 31 million, about 8.5 million people could directly benefit from the severe weather protection that mangroves and coral reefs offer.

Previous research has already demonstrated that conserving mangrove and reef ecosystems can help buffer the risk of flooding and inundation these communities face – for example, a 100-meter-wide coastal strip of mangroves can reduce wave heights by as much as two-thirds. Coral reefs buffer wave energy by up to 97% in some contexts, significantly reducing erosion and cutting flood-damage costs in half annually.

The study published today identifies where this risk reduction service is most important and how many of those 30+ million highly vulnerable people could potentially benefit from the protection of these ecosystems.

“Coastal populations are particularly exposed to the effects of climate change through increased storm frequency or intensity and rising sea levels, but nature plays a key role in reducing their vulnerability,” said Hole. “Ecosystem-based adaptation, or the use of nature to lessen the impacts of climate change, can improve the safety and resiliency of coastal areas.”

By looking at where mangrove and coral reefs are located in close proximity to coastal populations globally, the researchers estimate that around one quarter of the most highly vulnerable coastal populations (around 8.5 million people) are likely to benefit from the risk reduction provided by these ecosystems. The authors note this is a conservative estimate – the number of people whose risk is reduced increases to more than 13 million people if vulnerable communities are included.

Highly vulnerable, coastal regions that would benefit the most from the conservation of mangroves and coral reefs span across Central America, the Caribbean, Eastern Africa, Southeast Asia and the South Pacific region. And yet only 38% of mangroves and 11% of coral reefs located along the most vulnerable coastlines are protected, according to the study.

Developed by the study’s authors, these regions were identified using a measure of “adaptive-capacity” designed to synthesize economic data, education levels and other societal factors that often impact a region’s ability to respond to climate change.

“Coral reef and mangroves serve as cost-efficient buffers against the adverse impacts of climate change, and they already play important roles in protecting human lives and livelihoods, while providing a multitude of biodiversity benefits,” said Holly Jones, Northern Illinois University scientist and lead author of the study. “Simply put, it’s much cheaper to conserve a mangrove than to build a sea wall.”

Not only are investments in the conservation and restoration of mangroves and coral reefs a smart economic choice in terms of storm protection, but investments in the former can also help slow global warming.

Mangroves capture and store extraordinary amounts of carbon in their trunks, roots and sediments. Yet humans are rapidly destroying these reserves of “Blue Carbon,” both in mangroves, but also in other coastal ecosystems such as seagrass beds, and salt marshes. Already, one third of these coastal ecosystems have been lost to a variety of factors including land-use change, which means there is an enormous opportunity to increase protection and reforestation efforts in these regions.

“Ensuring the resiliency of mangroves is a win-win-win for people, nature and the climate. Mangroves store more carbon than any other forest ecosystem on Earth, drawing CO2 down from the atmosphere and storing it for decades, which helps to slow global warming,” said Hole. “As interest in ecosystem-based adaptation continues to grow, its vital that it’s multiple co-benefits are part of the conversation.”

The study found that mangrove ecosystems protecting the most highly vulnerable coastal communities store around 896 million metric tons of carbon. Moreover, they provide habitats for a host of plant and animal species, act as nursery grounds for some of the most important artisanal and economic fisheries in the world’s oceans, and support tourism and recreational activities that contribute to the livelihoods of tens of millions of people.

About Conservation International
Conservation International works to protect the critical benefits that nature provides to people. Through science, partnerships and fieldwork, Conservation International is driving innovation and investments in nature-based solutions to the climate crisis, supporting protections for critical habitats, and fostering economic development that is grounded in the conservation of nature. We work in 30 countries around the world, empowering societies at all levels to create a cleaner, healthier and more sustainable planet. Follow Conservation International's work on Conservation News, Facebook, Twitter, Instagram and YouTube.

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