Coastal flooding costs and carbon accumulation pressures are pushing researchers to quantify what natural infrastructure can realistically deliver alongside engineered flood defenses.
Planting mangroves in combination with human-made structures such as dikes could protect more than 140,000 people from flooding and save up to $800 million in flood damage globally each year, according to a study published in PNAS on January 20. The research modeled mangrove restoration scenarios layered on top of existing flood defenses to identify where combined approaches would produce the greatest returns.
The case for mangroves as physical barriers has data behind it. When Hurricane Ian struck southwest Florida in 2022, storm-powered waves reached up to 18 feet (5.5 meters), killing 158 people and generating $110 billion in damage statewide. Coastal areas with mangrove cover recorded 30% less damage than those without, saving an estimated $13 billion. “Mangroves act as a sponge to incoming waves,” said Daniel Friess, an environmental scientist at Tulane University. “Their dense tangle of aboveground roots are great at soaking up incoming wave energy.”
The mechanism is straightforward: mangroves occupy the intertidal zone between ocean and land, their root systems dissipating wave energy before surges reach built infrastructure. Climate change is expected to increase hurricane frequency and drive higher storm surges through sea level rise, conditions that would amplify the value of that buffer.
The Carbon Calculation
The protective function is only part of the argument. A separate 2025 study found that restoring 1.1 million hectares (2.7 million acres) of mangroves globally would remove approximately 0.93 gigatons of carbon dioxide from the atmosphere — nearly triple the annual emissions from passenger cars in the United States. The estimated cost of that restoration: $10.73 billion.
To identify viable restoration sites, the PNAS research team used satellite data to map where mangroves have been lost and assessed whether current hydrological conditions in those areas could support regrowth. “We used a published mangrove restoration tool, which looks into where the mangroves have been lost based on satellite data, the hydrological conditions of those areas now,” said study lead author Timothy Tiggeloven, a climate adaptation specialist at Vrije Universiteit Amsterdam.
What Is Blocking Progress
The scale of the opportunity sits against a deteriorating baseline. A 2024 assessment by the International Union for Conservation of Nature found that more than half of Earth’s mangrove ecosystems face collapse risk by 2050. Agriculture and aquaculture are the primary drivers of that loss, replacing forests that took decades to establish.
Restoration at meaningful scale faces compounding challenges: identifying hydrologically suitable sites, securing land that has often been converted to productive agricultural use, and funding projects whose benefits — flood protection and carbon sequestration — accrue broadly rather than to any single investor. The $10.73 billion restoration cost figure from the 2025 study implies coordination across dozens of countries and funding mechanisms that do not yet exist at the required scale.
The research does not resolve those institutional obstacles, but it provides a geographically specific cost-benefit framework that governments and conservation bodies can use to prioritize where intervention would deliver the highest combined return on flood protection and carbon removal.
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