UPSC Prelims 2021 Q19: Environment & Ecology – Climate Change & Greenhouse Gases
- (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
Answer: (a) Carbon captured by oceans and coastal ecosystems
Explanation
Blue Carbon: What It Is
| Type of Carbon | Ecosystem | Storage Duration |
|---|---|---|
| Blue carbon | Oceans and coastal ecosystems (mangroves, seagrass, salt marshes) | Long-term (centuries to millennia) |
| Green carbon | Terrestrial forests and vegetation | Decades to centuries |
| Brown carbon | Peat and organic soils | Long-term but fragile |
| Black carbon | Fossil fuels and combustion residues | Depends on source |
Blue carbon refers to carbon captured and stored by the world's oceans and coastal ecosystems. Mangroves, seagrasses and salt marshes sequester carbon 4-5 times faster per hectare than terrestrial forests, and lock it in waterlogged soils where it can persist for millennia. India's Sundarbans is a major blue carbon reservoir.
Answer: (a) Carbon captured by oceans and coastal ecosystems.
Why each option is right or wrong
- (a) CORRECT. Blue carbon is carbon captured by oceans and coastal ecosystems (mangroves, seagrasses, salt marshes). These systems are among the most efficient carbon sinks per hectare.
- (b) Incorrect. Carbon in forest biomass and agricultural soils is 'green carbon' or 'terrestrial carbon'.
- (c) Incorrect. Carbon in fossil fuels is called geological or fossil carbon.
- (d) Incorrect. Atmospheric carbon is called 'atmospheric CO2' or greenhouse carbon stock, not blue carbon.
Key point
Blue carbon = carbon stored in oceans + coastal ecosystems (mangroves, seagrass, salt marshes). Sequesters 4-5x faster per hectare than land forests. Locked in waterlogged sediments for millennia. India's Sundarbans is a major reservoir.
Remember
Blue carbon is carbon captured by oceans and coastal ecosystems - mangroves, seagrasses and salt marshes. These are the most efficient carbon sinks per hectare, storing carbon in waterlogged sediments for millennia. Correct answer: (a).
Common mistakes
- Confusing blue carbon (oceans/coastal) with green carbon (forests/soil).
- Not knowing mangroves are more efficient carbon sinks per hectare than rainforests.
- Missing that blue carbon loss (mangrove destruction) releases stored carbon rapidly - a major climate risk.
Exam tip
Carbon storage hierarchy: Blue (oceans/coastal) > Brown (peat) > Green (forests) > Atmospheric. International Blue Carbon Initiative (2011) launched by Conservation International, IOC-UNESCO, IUCN. India's Mangrove Alliance for Climate (MAC, COP27) is relevant.
Sources
- The Blue Carbon Initiative - IOC-UNESCO / Conservation International / IUCN
- Indian Council of Forestry Research and Education (ICFRE) - Mangrove Carbon Studies