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UPSC Prelims 2021 · Environment · Warming World
What is blue carbon?
- (a) Carbon captured by oceans and coastal ecosystems
- (b) Carbon sequestered in forest biomass and agricultural soils
- (c) Carbon contained in petroleum and natural gas
- (d) Carbon present in atmosphere
Show the answer and explanation
Answer: (a) Carbon captured by oceans and coastal ecosystems
Blue carbon is carbon captured by the ocean and especially by coastal ecosystems (mangroves, salt marshes and seagrass meadows) and buried in their waterlogged soils for centuries.
The idea
Carbon is given a colour by where it is stored. Green carbon is in forests and soils on land. Blue carbon is in the ocean and coastal ecosystems. Black carbon is soot. Brown carbon comes from burning organic matter.
Mangrove, salt marsh or seagrass takes in CO₂ → Dead leaves and roots fall into waterlogged mud → No oxygen in the mud → very slow decay → Carbon stays buried for centuries
Why the others are wrong
(b) That is green carbon: forests and soils on land.
(c) That is fossil carbon.
(d) That is simply carbon in the air.
The trap
“Blue” makes you think of the open ocean or the sky (option d). Blue carbon is mainly about the COASTS: mangroves, marshes and seagrass.
Also know
Waterlogged, low-oxygen mud slows decay, so carbon stays buried for centuries to millennia, and destroying these ecosystems releases it. Globally there is the Blue Carbon Initiative (IUCN, Conservation International, IOC-UNESCO); India has MISHTI for mangroves (2023).
🔒 Blue carbon = ocean and coastal carbon: mangroves, salt marshes, seagrass. It is stored in the sediment.