Mangrove forests, rare tidal woodlands at the interface of land and sea, are extraordinary ecosystems that bridge freshwater and marine environments. These forests support rich biodiversity and invaluable nursery habitat for fish and crustaceans, while also providing food, shelter, and cultural resources to millions of coastal communities.
Think of mangroves as sea walls: their dense, prop-root networks buffer shorelines against tides, storm surges, tsunamis and erosion. They also host extraordinary carbon vaults in their waterlogged soils. Tomorrow marks the International Day for the Conservation of the Mangrove Ecosystem, so this blog is dedicated to celebrating the scientific understanding of these blue carbon ecosystems, from soil chemistry to coastal geomorphology, and highlighting global efforts to protect and restore them.
Mangrove roots and coastal stability
Mangrove trees, like this solitary specimen in Flores, Indonesia use stilt-like roots to form a complex barrier in shallow water. These root tangles trap sediment and dissipate wave energy, which leads to a gradual buildup of coastal soils. Islands with mangrove forests experience far less shoreline erosion and storm damage than bare coasts.
In fact, dense mangrove belts can reduce ocean wave heights dramatically; for instance, a 500-meter mangrove strip can cut wave heights by 50–99%. Recent modeling shows that mature mangroves can protect up to 97–99% of adjacent sandy coasts from erosion, even under projected sea-level rise scenario. In Ghana’s Volta Delta, introducing healthy mangrove stands reduced long-term shoreline erosion by roughly 97% in present-day scenarios (and 99% under modest sea-level rise). These geomorphological benefits, such as stabilizing sediments, building landforms, and buffering waves, make mangroves one of nature’s most effective coastal defense strategies.
Mangrove wetlands also play a pivotal role in sediment dynamics. As rising seas threaten many coasts, only wetlands that accrete sediment are fast enough can keep up with the pace. Mangrove roots trap silt and organic debris, consequently raising the soil surface over time. But when sea-level rise or extreme events outpace accretion, mangroves can drown. A 2024 study of the Maldives found that record-high sea levels (over 30 mm per year) far exceeded mangrove sedimentation (~6.4 mm/yr), triggering dieback on a quarter of island mangrove areas after 2020.
Such findings demonstrate that mangroves are highly resilient, but only within certain thresholds of change. In regions where mangroves can naturally migrate landward or where sediments are abundant, they tend to hold their own; while elsewhere, engineering and restoration may be needed to help wetlands survive rising waters.
Soils and blue carbon: Mangroves’ hidden reservoirs
Mangrove soils are among the most carbon-rich on Earth. Despite covering only ~0.4% of global forests, mangrove ecosystems can sequester carbon at nearly four times the rate of terrestrial forests. In fact, a single hectare of mangrove can store over 3,700 tons of carbon in its biomass and sediments.
Globally, mangrove forests hold on the order of 21 billion tons of carbon, mostly locked away in waterlogged soils. These anoxic, peat-like soils slow the decay of organic matter, preserving up to ~90% of the carbon that falls onto the forest floor. Over centuries, layers of fine sediment and dead roots accumulate, resulting in meters-thick mangrove peat layers.
This “blue carbon” function has big climate implications. Mangroves capture about 10–15% of all coastal carbon stocks, even though they occupy <1% of the coastline. In countries with extensive mangroves, these ecosystems are critical carbon sinks. Indonesia’s mangroves, for example, store roughly 3.14 petagrams of carbon (33% of the world’s coastal carbon). And every loss of mangrove triggers large emissions: studies estimate that deforestation of 1% of mangrove cover would release roughly 200 billion tons of carbon.
Indeed, although mangroves represent only ~0.7% of global land, mangrove deforestation accounts for about 10% of emissions from all forest loss. Conversely, conserving and restoring mangrove soils can deliver outsized carbon-climate benefits; global climate commitments now increasingly recognize mangroves as Nature-based Solutions. By 2023, 97 countries had included coastal and marine ecosystems (often mangroves) in their Paris Agreement NDCs, and 61 countries called for conserving or restoring mangroves as part of their carbon reduction strategies.
Mangrove blue carbon is not only a static stock but also a flux. Mangroves export (“outwell”) dissolved and particulate carbon into adjacent waters via tidal pumping. Recent tracer studies using radium isotopes found that porewater and tidal flow can carry large amounts of dissolved carbon (mainly bicarbonate) from mangrove soils to the coastal ocean. Surprisingly, this outwelling of carbon can actually increase the long-term carbon burial of the mangrove system. One field study in Brazil found that bicarbonate released during tidal exchange boosted the system’s overall carbon sequestration by ~234% compared to burial alone. In practical terms, this means that mangroves trap CO₂ not only in place but also in the surrounding marine environment!
Biodiversity, fisheries, and food security
Mangrove forests teem with life. They support vast food webs in coastal zones, serving as nursery grounds for fish, shrimp, crabs, and even some corals. Over 341 globally threatened species (from tigers to turtles) rely on mangroves at some point in their life cycle. One comprehensive assessment estimates that nearly 800 billion individual fish and invertebrates depend on mangroves each year.
By providing safe breeding grounds and feeding areas, mangroves underwrite the productivity of nearby coral reefs, fisheries, and food supplies. For coastal communities in Southeast Asia, West Africa, Latin America, and other regions, mangroves are directly linked to livelihoods, thus, losing mangroves doesn’t just mean losing biodiversity; it means losing food security, ancestral practices, and the resilience of entire communities.
Beyond fisheries, mangroves contribute to human well-being in many ways. They filter sediments and pollutants from rivers before they reach the ocean, improving water quality for reefs and people. The resources they yield – timber, fuelwood, honey, fruits – are crucial for millions of poor communities.
Indeed, UNESCO notes that managing and restoring mangroves is a cost-effective strategy to help ensure food security and sustainability for coastal populations. During disasters, mangroves reduce vulnerability: their vegetation can markedly lessen the heights of storm surges and tsunamis reaching inland. Think of the 2004 Indian Ocean tsunami: It caused far less damage in areas shielded by intact mangroves than in cleared areas.
People and policy: Restoration, threats, and opportunities
Many coastal communities rely on mangroves for building materials, as shown by this stilt house made of mangrove wood in the Philippines. Such traditional uses highlight the intimate human–mangrove connection. However, unsustainable harvesting and conversion are major threats. Across the tropics, millions of hectares have been cleared for shrimp ponds, palm oil and rice farms, or simply cut for charcoal and timber. Approximately 43% of global mangrove loss from 2000–2020 was due to conversion to aquaculture, oil palm, and agriculture.
For example, Indonesia alone lost ~30% of its mangroves between 1980 and 2005, causing an estimated 0.19 Pg CO₂-eq annual emission from soil organic carbon. As these soils dry out, their deep carbon stores oxidize and escape as greenhouse gases, flipping a carbon sink into a source.
Climate change adds another layer of pressure. Rising sea levels, stronger cyclones and altered freshwater flows can stress mangroves. In some places like the densely populated Sundarbans (Bangladesh/India) or small Pacific islands, there is little room for forests to retreat inland, making them vulnerable if sediment supply is insufficient.
Over 50% of the world’s mangrove provinces (ecologically distinct regions) are now classified as threatened by factors including climate change. In the Caribbean, for instance, declining mangroves mean greater storm flooding and erosion – the Caroni Swamp in Trinidad (shown above) is a rare bulwark, and its loss would put nearby towns at much higher hurricane riskspace4water.org.
Still, there is reason for hope. Global mangrove loss rates have slowed down by 44% from 2000–2020, as awareness and mapping improve. New high-resolution satellite data (Global Mangrove Watch) have given conservationists unprecedented ability to track changes in near-real time. Countries like Seychelles and Costa Rica have explicitly pledged to protect 50–100% of their mangroves in updated Nationally Determined Contributions.
Innovative approaches are emerging: Integrated Mangrove Aquaculture (IMA) systems, for example, combine shrimp farming with mangrove conservation so that culture ponds are surrounded by restored forest, thus producing seafood while maintaining habitat. Community-led planting projects, from Senegal all the way to the Bahamas, have reforested tens of thousands of hectares using seedlings of local species.
On the international stage, mangroves now feature in major agreements. The UN Decade on Ecosystem Restoration (2021–2030) and the Ocean Decade explicitly include coastal wetlands. In 2019 the UN Environment Assembly urged all countries to support “mangrove conservation, restoration and sustainable management” via ecosystem-based policies.
The Kunming-Montreal Global Biodiversity Framework (2022) set a target of protecting and managing 30% of marine and coastal ecosystems by 2030 , a goal that highlights areas important to mangroves and even includes indicators for mangrove cover and fragmentation.
The Mangrove Breakthrough, launched at COP27, is a high-profile call to action: it aims to secure 15 million hectares of mangroves by 2030 with new financing (~$4 billion) for restoration and protection, supporting Paris Agreement commitments, Ramsar wetlands conservation, and the “30×30” and UN Decade targets.
Hundreds of organizations and governments have now joined a global Community of Action on mangroves, pledging science-based interventions to halt loss and restore forests.
My experience kayaking through Kilim Geoforest Park in Langkawi, Malaysia
I’ll never forget gliding silently through the labyrinth of mangrove tunnels at Kilim Geoforest Park in Malaysia last year. The experience felt otherworldly: dense, ancient trees looming overhead, the water dark and still, with the sound of macaques chattering overhead, and eagles circling in the limestone-clad sky.
But beyond the breathtaking beauty, our guide shared a powerful lesson: these mangroves saved lives. During the 2004 Boxing Day tsunami, much of Langkawi was shielded thanks to these tidal woodlands. Though the tsunami devastated nearby regions like Banda Aceh and Phuket, only one life was lost on Langkawi (compared to the thousands of lives lost in surrounding regions), which highlights the importance of nature’s fortification through the mangrove buffer.
Image of the author, Asmae Ourkiya, Kayakin in Kilim Geoforest Park in Langkawi, Malaysia
The mangroves’ complex root systems act as living seawalls. I learned that for wave heights, even small tsunamis, they slow and dissipate energy and therefore reduce impact on fertile coastal communities. Floating along in my kayak, I could almost feel that protective barrier acting as a natural bulwark and keeping the worst at bay.
Moving forward: Science, communities, and global collaboration
Modern soil and coastal science – including by EGU’s Soil System Sciences and Geomorphology divisions – is helping guide these efforts. For example, field and modeling studies quantify how mangroves shift sediments and carbon under different sea levels and land uses. Research on greenhouse-gas fluxes in mangrove soils (CO₂ and CH₄) in Indonesia, the Red Sea, and elsewhere is improving carbon accounting in national inventories. Geomorphologists use aerial roots and sediment maps to design optimal restoration zones that balance erosion and growth.
At the same time, success usually comes from locally driven solutions. Engaging Indigenous knowledge and community stewardship has repeatedly improved outcomes. Protecting mangroves also means linking policies: science-informed Wetland Inventories, coastal zoning, climate adaptation plans, and biodiversity strategies should all recognize mangroves’ multiple values.
Financially, blue carbon projects and payments for ecosystem services (e.g. carbon credits, disaster insurance) are emerging tools to channel more funding for mangroves. Initiatives like the Global Mangrove Alliance, IUCN Mangrove Specialist Group and Ramsar’s mangrove resolutions are building scientific networks and best-practice guidelines to scale up effective conservation.
In short, the science is clear: healthy mangroves stabilize coasts, trap sediment, and sequester vast amounts of carbon. They are natural defenses against storms and erosion, vibrant biodiversity hotspots and sources of food and livelihoods. Yet they remain “among the most threatened forests” in the world.
This International Day for Mangrove Conservation, I call on scientists, policymakers, and citizens alike to champion mangroves (educate, share, and even talk about them with your friends!) and the latest research, press for stronger protection, and help, in your own way, restore these “natural engineers” wherever possible. By uniting soil science, geomorphology, ecology, and community action, we can ensure that mangroves continue to shelter our shores and climate for generations to come.
