Blue carbon

Blue carbon is the carbon captured and stored in coastal and marine ecosystems, such as mangroves, seagrass meadows and salt marshes. These habitats act as powerful carbon sinks, absorbing CO2 and locking it away in waterlogged soils for centuries, often at rates per unit area well above those of land-based forests.

Where blue carbon is found

• Mangroves: forests in the intertidal zones of tropical and subtropical coasts.
• Seagrass meadows: underwater flowering-plant ecosystems in shallow coastal waters.
• Salt marshes: coastal wetlands regularly flooded by the tides.

Why it matters

• Carbon storage: according to the Blue Carbon Initiative, these ecosystems can sequester carbon several times faster per unit area than tropical forests, and store large stocks in their soils despite covering a small fraction of the ocean.
• Coastal protection: they reduce wave energy and help prevent erosion and flooding.
• Biodiversity: they serve as nurseries for many marine species.
• Water quality: they filter nutrients and pollutants.

Main threats

• Habitat loss: coastal development, aquaculture and pollution.
• Climate change: sea-level rise and ocean acidification.
• Overexploitation: for example conversion of mangroves into shrimp farms.

Conservation and restoration

Protecting and restoring blue carbon ecosystems helps to:

• Mitigate climate change by maximising long-term CO2 storage.
• Protect coastal communities as natural barriers against storms.
• Sustain fisheries by preserving marine productivity.

Blue carbon is increasingly used in nature-based solutions and in the voluntary carbon market, where credible projects must meet strict standards for permanence and measurement. Key references include the Blue Carbon Initiative and the Global Mangrove Alliance.

At Manglai we help companies measure their carbon footprint and prepare their sustainability reporting. Discover how Manglai can help you.