Context:
The open seas offer an immense opportunity to slow climate change if we invest now and do it right.
Answer:
Oceans, covering over 70% of the Earth’s surface, act as the planet’s “blue lungs,” absorbing 25% of anthropogenic CO₂ emissions and over 90% of excess heat from greenhouse gases. Their immense capacity to moderate climate change positions them as a vital ally in combating global warming. However, realising this potential requires balancing opportunities with ecological and technical challenges.
Role and Potential of Oceans in Moderating Global Climate Change and Carbon Sequestration:
- Carbon Dioxide Absorption: Oceans absorb CO₂ through natural processes like dissolution, transforming it into dissolved inorganic carbon.
- The Indian Ocean alone has the potential to capture 25-40% of global marine CO₂.
- Heat Regulation: Oceans store and redistribute heat globally, mitigating extreme temperature variations.
- The Indian Ocean Dipole influences monsoons, highlighting its role in regional climate stability.
- Biological Carbon Sequestration: Marine ecosystems like mangroves, seagrasses, and phytoplankton absorb and store carbon through photosynthesis.
- Sundarbans mangroves sequester approximately 4 million tonnes of CO₂ annually.
- Abiotic Carbon Sequestration: Techniques like ocean alkalinity enhancement (OAE) can lock carbon for tens of thousands of years.
- Experimental studies show OAE’s potential to sequester 1-15 billion tonnes of CO₂ annually.
- Ocean Circulation and Carbon Transport: Currents transport carbon to deep ocean layers, ensuring long-term storage.
- Thermohaline circulation, often termed the “global conveyor belt.”
Opportunities Associated with Ocean-Based Climate Change Mitigation Strategies:
- Scalability and Permanence: Oceans offer vast storage capacity, with abiotic methods providing more permanent solutions.
- Synergies with Biodiversity Conservation: Marine carbon projects support biodiversity and improve resilience of marine ecosystems.
- Mangrove afforestation under the National Adaptation Fund for Climate Change and restoration of coral reefs under National Coastal Mission.
- Global Climate Goals Alignment: Marine-based strategies can bridge the gap to achieve net-zero targets.
- India’s commitment under the Paris Agreement includes enhancing blue carbon ecosystems.
- Co-benefits for Livelihoods and Fisheries: Healthy marine ecosystems improve fish stocks, supporting livelihoods in coastal communities.
- The livelihoods of over 4 million in India depend on sustainable ocean management.
- Economic Opportunities: Development of blue carbon markets and marine technologies can generate employment and revenue.
- India’s Blue Economy policy emphasizes sustainable exploitation of ocean resources.
- NIOT (National Institute of Ocean Technology) is exploring bio-alkalinity solutions.
Challenges Associated with Ocean-Based Climate Change Mitigation Strategies:
- Ocean Acidification: Absorption of CO₂ increases acidity, harming marine biodiversity.
- Coral bleaching in the Andaman & Nicobar Islands due to acidification threatens marine ecosystems.
- Unintended Ecological Consequences: Techniques like iron fertilisation may disrupt marine food chains and deplete oxygen levels.
- Experimental phytoplankton blooms in the Pacific led to oxygen-poor dead zones.
- Energy-Intensive Processes: Abiotic methods like electrochemical processes require significant energy inputs, increasing operational costs.
- Scaling OAE in Indian waters would necessitate extensive renewable energy support.
- Regulatory and Governance Hurdles: Skepticism regarding the safety and effectiveness of abiotic techniques and lack of comprehensive international frameworks for ocean-based carbon solutions hinders their adoption.
- Monitoring and Verification Challenges: High costs and technical difficulties in measuring long-term carbon sequestration impede implementation.
By addressing challenges and scaling up sustainable solutions, oceans can play a transformative role in achieving climate resilience and securing a sustainable future for humanity.
‘+1’ Value Addition:
- As on land, marine carbon capture strategies fall into two categories. (i) Biotic approaches take advantage of living systems like mangroves and macroalgae (ii) Abiotic approaches manipulate physical or chemical properties, such as through ocean alkalinity enhancement (OAE).
- Carbon sequestration potential of biotic solutions is modest, typically capped at less than one billion tonnes of carbon dioxide every year and storage durations are limited to hundreds or at best thousands of years.
