A mangrove passage near Everglades City, Mangrove forests such as this one are rapipidly pushing north along Florida coaslines. Photo credit Sarasota Herald-Tribute

Mangroves: The Forests We Almost Erased—and Why We Cannot Afford to Lose Them

Mangrove forests are among the most important ecosystems along the world’s coastlines, playing a vital role in both environmental stability and climate regulation. Classified as “coastal blue carbon” ecosystems, mangroves function as powerful natural carbon sinks. They capture carbon dioxide from the atmosphere and store it within their dense plant tissues and deep, waterlogged soils. This long-term carbon storage makes mangrove forests essential allies in mitigating climate change, despite their relatively small global footprint.

Although seagrass meadows, salt marshes, and mangrove swamps occupy only about 0.2 percent of the seafloor, they are responsible for sequestering more than half of the ocean’s carbon. Mangrove forests are particularly efficient: per acre, they can store up to four times more carbon than tropical rainforests. While mangroves make up less than 2 percent of marine environments, they account for an estimated 10 to 15 percent of global carbon burial, highlighting their disproportionate impact on Earth’s carbon cycle.

The carbon-storage capacity of mangroves is striking at even the smallest scale. A single acre of mangrove forest can store approximately 1,450 pounds of carbon each year, roughly equivalent to the emissions produced by a car driving nearly 6,000 miles—across the United States and back. When mangroves are destroyed, this stored carbon is released into the atmosphere, accelerating climate change rather than slowing it.

Beyond their role in climate mitigation, mangrove forests provide critical protection against extreme weather. Their dense, interlocking root systems act as natural barriers, absorbing and dispersing wave energy from storms. Research shows that a one-kilometer-wide mangrove forest can reduce the destructive force of hurricanes, cyclones, and tsunamis by up to 90 percent. As climate change intensifies storms and raises sea levels, this protective function becomes increasingly essential for coastal communities.

Despite their immense value, mangrove forests have been lost at an alarming rate—between 20 and 35 percent globally over the past 50 years. This loss represents not only the destruction of a unique ecosystem but also the removal of one of nature’s most effective tools for climate resilience and coastal protection. Preserving and restoring mangrove forests is therefore not just an environmental priority, but a critical investment in the future stability of both coastal ecosystems and human societies.

At the boundary where land dissolves into subtropical and tropical seas, mangroves take root in places few other trees can survive. These resilient forests thrive in low-oxygen soils, bathed daily by tides and surrounded by slow-moving waters that allow fine sediments to settle. For centuries, mangroves quietly performed their work—stabilizing coastlines, sheltering wildlife, and supporting human communities. Yet for much of the twentieth century, they were misunderstood, dismissed as mosquito-infested swamps unworthy of protection.

Before 1970, mangroves were widely viewed as obstacles to progress. Clearing them seemed harmless, even beneficial. As a result, destruction accelerated at an astonishing rate. According to the United Nations, nearly 14,000 square miles of mangrove forests were destroyed between 1980 and 2005, leaving fewer than 60,000 square miles worldwide by the mid-2000s. Trees were harvested for timber, wetlands were filled to control mosquitoes, and vast areas were converted into shrimp farms or reclaimed for development. What was lost, however, was far more valuable than the land that replaced it.

Mangroves are among the most biologically rich ecosystems on Earth. They are associated with more than 1,500 animal species, providing shelter and breeding grounds for fish, amphibians, birds, reptiles, and marine mammals. In the Sundarbans of India and Bangladesh—the largest mangrove forest in the world—approximately 500 Royal Bengal tigers roam an intertidal landscape that supports one of the planet’s most iconic predators. Yet this biodiversity is under threat. Fifteen percent of mangrove-associated species now face extinction, including sharks, manatees, otters, and even sloths in regions spanning the Americas and the Asia-Pacific.

The importance of mangroves extends far beyond the forest itself. Their tangled root systems act as living infrastructure, absorbing wave energy and trapping sediments that would otherwise be washed away. By holding sand, dirt, and silt in place, mangroves reduce erosion and improve water quality. They filter nutrients from agricultural and urban runoff, preventing harmful algal blooms that can suffocate marine life. Nearby coral reefs and seagrass beds depend on these water-purifying services to survive, forming a connected web of coastal ecosystems that rise or fall together.

Perhaps most striking is the role mangroves play in regulating Earth’s climate. Though they account for less than one percent of tropical forests worldwide, mangroves are extraordinary carbon sinks. Their soils store two to four times more carbon per acre than terrestrial forests. When mangroves are destroyed, this carbon—locked away for centuries—is released back into the atmosphere, intensifying climate change. Between 1996 and 2020, the emissions from mangrove loss were equivalent to roughly four times the global CO₂ emissions produced by fossil fuels and cement manufacturing in 2018 alone.

Despite occupying less than two percent of marine environments, mangroves are responsible for 10 to 15 percent of global carbon burial. A single acre can store about 1,450 pounds of carbon each year—roughly equivalent to the emissions from driving a car across the United States and back. These numbers reveal a powerful truth: protecting mangroves is not a symbolic gesture; it is a climate solution.

Mangroves also stand on the front lines of climate adaptation. As sea levels rise and storms intensify, coastal communities face growing risks from erosion, flooding, and storm surges. Mangrove forests act as natural shields, absorbing and dissipating wave energy through their dense root systems. A one-kilometer-wide mangrove forest can reduce wave energy by up to 90 percent, offering protection that concrete seawalls struggle to match. With 40 percent of the world’s population living within 100 kilometers of the coast, the survival of mangroves is inseparable from human safety.

Once written off as worthless swamps, mangrove forests are now recognized as some of the most valuable ecosystems on the planet. They feed communities, shelter wildlife, stabilize coastlines, and quietly lock away carbon that would otherwise fuel climate breakdown. The tragedy is not that mangroves exist in difficult places—but that for so long, we failed to see their worth. The opportunity before us now is clear: protect what remains, restore what has been lost, and allow these extraordinary forests to continue doing what they have always done—protecting life at the edge of land and sea.

In 1991, a powerful cyclonic storm made landfall in an area of Bangladesh where the mangroves had been stripped away. The 20-foot (6-meter) storm surge, comparable to the height of Hurricane Katrina’s, contributed to the roughly 138,000 people killed by the storm (for comparison, Katrina killed 1,836). The damage caused by the 2004 tsunami spurred impacted countries to rethink mangrove importance, and many restoration projects are working to rebuild lost forests.

Photographs showing a time series of a restored mangrove at West Lake Park, Hollywood, Florida, USA. The channels were restored by grading the site to match the slope of an adjacent relatively undisturbed mangrove wetland and constructing tidal creeks. No planting of mangroves occurred, and all three Florida mangrove species established naturally on their own (Lewis, 1990, 2005). (A) initial completion of grading and construction of tidal creeks (July, 1989), (B) after 28 months, and (C) after 78 months (photos by Dr. Roy R. Lewis III).

Case Study: West Lake Park near Ft. Lauderdale, Florida.

In 1986, ichthyologist Robin Lewis worked to restore 1,300 acres of mangroves at West Lake Park near Fort Lauderdale, Florida, where about 200 acres were completely dead, covered in dirt while invasive plants thrived.

Lewis concluded that traditional mangrove restoration resembles forest planting. He cultivates seedlings in greenhouses, relocating them to mudflats, but this is often ineffective. For instance, the World Bank spent $35 million planting nearly 3 million seedlings in the Central Visayas from 1984 to 1992; by 1996, fewer than 20 percent survived. Many global mangrove restoration efforts fail because wetland environments are dynamic, and seedlings struggle if water levels aren't ideal.

Typically, plantings use only one mangrove species, unlike the diverse habitats found in natural mangrove forests. “Mangrove forests consist of diverse trees and communities, showcasing complexity. Single-species plantings result in simpler habitats that support less biodiversity.”

Lewis began restoring a ten-acre plot with a hydrologist to map the water flow. After three years, he initiated the complete restoration project, which required significant dirt relocation. With bulldozers, he shaped a gentle slope for tidal flow. By 1989, the site looked barren, but by 1991, seedlings took root, and by 1996, Florida’s three mangrove species were established. A survey revealed as many fish and aquatic species as in a nearby healthy mangrove site, attracting shorebirds.

“There wasn’t a single mangrove planted in the whole project,” Lewis said. “Mother Nature can repair herself if given the opportunity.” His methods have revived 30 mangrove sites in the U.S. and been adopted in 25 countries, including Thailand and Indonesia. This work requires careful planning, study, and patience but is vital for restoring the world’s mangroves.

A threat and a solution – tourism’s role in mangrove protection. From the Race to Resilience Race to Zero website.https://climatechampions.unfccc.int/a-threat-and-a-solution-tourisms-role-in-mangrove-protection/

Florida mangroves mitigated flood damage

The Nature Conversancy reported in 2017, mangroves in Florida mitigated flood damage from Hurricane Irma by nearly 25%. A study by scientists from the engineering, insurance, and conservation sectors found that mangroves prevented $1.5 billion in direct flood damages. Mangroves also protected over 626,000 people across Florida. Their effectiveness in reducing flood risks increases with their abundance and placement in front of densely populated areas. These vital ecosystems safeguarded over half a million residents and averted billions in losses across counties such as Collier, Lee, and Miami-Dade. They helped avoid about $802 million in losses, along with an additional $580 million. Furthermore, mangroves shielded valuable coastal properties from more than $134 million in potential flood damage.

Case Study: Tahiry Honko, Madagascar Mangrove Carbon Project

The Tahiry Honko mangrove carbon project is one of the largest of its kind. It is making an impact by enhancing community resilience and offering climate solutions through the restoration of precious mangrove forests. In the Velondriake Locally Managed Marine Area (LMMA) in southwest Madagascar, ten villages have come together to adopt a management strategy that addresses the long-term degradation of mangrove forests caused by their use as building materials and firewood.

This collaborative approach not only generates carbon credits but also provides sustainable income for these villages and the management association. It's fantastic to see how this initiative fosters conservation, reforestation, and the sustainable use of over 1,200 hectares (3,000 acres) of mangroves, all while promoting alternative livelihoods. Impressively, it prevents nearly 1,400 tons of CO2 emissions each year and brings in carbon credit revenues that support LMMA management and community services. The Plan Vivo Foundation has validated the remarkable work of this project. This highly respected certification body sets essential standards for community and smallholder land-use and marine projects.

This gave investors funded by the Darwin Initiative through UK Government funding, the Global Environment Facility (GEF) through its Blue Forests Project, the MacArthur Foundation, and UK Aid confidence that this project represents the best quality for nature and climate communities.

For over 15 years, Blue Ventures has joyfully partnered with coastal communities in Madagascar to create innovative benefits from conservation, especially by valuing carbon sequestration and fish production. By protecting and restoring mangroves, these communities play a crucial role in preserving significant carbon stores in vegetation and sediments, effectively preventing CO₂ release. As of October 2019, these avoided emissions are highly valued within the voluntary carbon market.

This project is a wonderful example of locally led conservation, embracing reforestation and ensuring the sustainable use of over 1,200 hectares of mangroves. It also includes initiatives aimed at building alternative livelihoods—like sea cucumber and seaweed farming, as well as mangrove beekeeping—all while supporting the delivery of health and education services in the region.

Consequently, the loss of mangroves can have significant and long-lasting impacts on the health, safety, and prosperity of millions of people. It can also hamper the fight against climate change and the ability to deal with it.