Blue Carbon Dynamics in Coastal Ecosystems

Blue carbon refers to the carbon captured and stored by coastal vegetated ecosystems, principally mangroves, saltmarshes and seagrasses. These habitats sequester atmospheric CO₂ through photosynthesis and bury it in soils and sediments, where low oxygen levels slow decomposition and allow long-term storage. Dynamics are governed by interactions among primary production, tidal exchange, sediment deposition, microbial processes and physical disturbance. Human activities such as land-use change, aquaculture and coastal development have driven substantial losses of blue carbon stocks, releasing stored CO₂ and undermining natural climate mitigation. Restoration and conservation efforts can reverse this trend, enhancing carbon sequestration, bolstering coastal resilience and contributing to ocean alkalinity regulation. The global significance of these ecosystems is underscored by their disproportionate role in carbon storage per unit area, their biodiversity support and the range of ecosystem services they provide to coastal communities.

Research from Nature Portfolio

Recent studies have employed biogeochemical modelling to demonstrate that restoration of coastal vegetation not only increases organic carbon burial but also drives local enhancement of ocean alkalinity, thereby promoting durable atmospheric CO₂ removal. Enhanced alkalinity arises from elevated rates of anaerobic respiration and dissolution of calcium carbonate within sediments, reinforcing the value of blue carbon restoration in climate policy frameworks. Complementary global analyses comparing mangrove reforestation—replanting in historically vegetated zones—with afforestation on novel intertidal flats show that reforestation can yield around 60 per cent greater carbon accumulation over four decades, owing to optimal nutrient regimes and tidal positioning. A seminal synthesis in the field has outlined priority research needs, including precise mapping of blue carbon extents, determination of carbon provenance, quantification of greenhouse gas fluxes post-disturbance and evaluation of management practices that maximise carbon retention.

Blue Carbon Dynamics in Coastal Ecosystems publication trend

The graph below shows the total number of articles in blue carbon dynamics in coastal ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Blue Carbon: Carbon captured by coastal vegetated ecosystems and stored in biomass and sediments.

Carbon Sequestration: Process by which CO₂ is fixed from the atmosphere and stored long-term in ecosystems or geologic reservoirs.

Ocean Alkalinity Enhancement: Increase in seawater buffering capacity through chemical processes that promote CO₂ uptake and reduce acidity.

Reforestation: Restoration of vegetation in areas where it previously existed, enhancing ecosystem function and carbon storage.

Afforestation: Establishment of vegetation in areas that historically did not support such ecosystems, often on marginal soils.

Anaerobic Respiration: Microbial breakdown of organic matter in oxygen-limited environments, influencing carbon cycling and alkalinity production.

References

1. Ocean alkalinity enhancement through restoration of blue carbon ecosystems. Nature Sustainability (2023).
2. Mangrove reforestation provides greater blue carbon benefit than afforestation for mitigating global climate change. Nature Communications (2023).
3. The future of Blue Carbon science. Nature Communications (2019).
4. Global declines in human‐driven mangrove loss. Global Change Biology (2020).
5. Estimating Global “Blue Carbon” Emissions from Conversion and Degradation of Vegetated Coastal Ecosystems. PLOS ONE (2012).