Key Terms & Concepts — UPSC Mains
Blue Carbon
"Carbon captured and stored by coastal and marine ecosystems — mangroves, seagrasses, and salt marshes — at rates far exceeding terrestrial forests"
Blue Carbon refers to the carbon dioxide sequestered and stored by coastal and marine ecosystems — specifically mangroves, seagrass meadows, and tidal salt marshes. These ecosystems capture carbon from the atmosphere through photosynthesis and store it in both living biomass and the sediment below (where it can persist for millennia). Per unit area, blue carbon ecosystems store 3–5 times more carbon than tropical forests and absorb CO₂ up to 50 times faster. Their destruction releases stored carbon rapidly, making conservation a dual climate-biodiversity priority.
High UPSC relevance for GS3 (Environment — climate change mitigation, biodiversity) and GS2 (Governance — coastal management, India's NDC commitments). India's Sundarbans (West Bengal/Bangladesh) is the world's largest mangrove delta and a critical blue carbon sink. The UNESCO Sundarbans microplastics study (2025) highlighted threats to this ecosystem's carbon storage capacity.
- 1 Blue carbon ecosystems — mangroves, seagrasses, tidal marshes (not coral reefs, which are calcium carbonate)
- 2 Carbon storage rate — 3–5× more per hectare than tropical forests; sediment storage lasts thousands of years
- 3 India's mangrove cover — ~4,992 sq km; Sundarbans (~4,200 sq km) is largest; Bhitarkanika (Odisha) second largest
- 4 Threat — 50% of global mangroves lost since 1980; India's mangrove cover marginally increasing (Forest Survey of India data)
- 5 When destroyed, blue carbon ecosystems release centuries of stored carbon — making loss a double liability
- 6 IPCC recognises blue carbon in national carbon accounting under NDCs
- 7 India's National Action Plan on Climate Change (NAPCC) includes mangrove conservation under NMSA
- 8 Microplastic pollution degrades seagrass and mangrove root systems — disrupting carbon sequestration
- 9 Blue Carbon Initiative — IUCN, CI, IOC-UNESCO partnership for blue carbon measurement and policy
The Sundarbans mangrove delta stores approximately 200 million tonnes of carbon in its soils — equivalent to decades of India's power sector emissions. Microplastic contamination found in Sundarbans sediments (2025 study) threatens the integrity of this blue carbon sink by disrupting the microbial communities that facilitate carbon burial.
