Context: A recent study indicates that 10–15% of the Sundarbans mangrove ecosystem is experiencing “critical slowing down”, signalling declining ecological resilience under environmental stress.
Key Highlights:
• About Sundarbans
- World’s largest mangrove forest located in the Ganga–Brahmaputra–Meghna delta
- Recognized as a UNESCO World Heritage Site
- Shared between India (40%) and Bangladesh (60%)
- Key rivers: Muriganga, Raimangal, Harinbhanga, Matla, Saptamukhi, Thakuran
• Critical Slowing Down
- Indicates reduced recovery capacity after disturbances
- Early warning sign of ecosystem collapse
• Climate-related Stress Factors
- Rising temperatures reducing species richness
- Erratic rainfall increasing salinity imbalance
- Reduced freshwater inflow affecting mangrove growth
- Increase in extreme weather events
• Ecological Changes
- Decline in canopy height and leaf traits
- Shift toward uniform forest structure (loss of biodiversity)
- Presence of both:
- Fast-growing species: Avicennia officinalis, Excoecaria agallocha
- Slow-growing species: Heritiera fomes, Bruguiera, Xylocarpus
- Some areas shifting from carbon sink → carbon source
• Impact of Cyclones
- Cyclones like Sidr, Rashmi, Aila have reduced resilience
- Large areas downgraded from high to moderate/low resilience
• Geographical Impact Zones
- Most affected: Central and south-eastern Sundarbans (seaward zones)
- Indian Sundarbans show lower resilience compared to Bangladesh
• Significance
- Crucial for biodiversity conservation
- Provides coastal protection against cyclones and storm surges
- Acts as a major carbon sink
- Supports livelihoods of coastal communities
Relevant Prelims Points:
• Mangrove Ecosystem
- Salt-tolerant vegetation in intertidal zones
- Acts as natural barriers against coastal erosion
• UNESCO World Heritage Site
- Recognized for outstanding universal value
• Carbon Sink vs Carbon Source
- Sink: absorbs more CO₂ than releases
- Source: emits more CO₂ than absorbs
• Salinity Gradient
- Key determinant of species composition in mangroves
• Cyclones in Bay of Bengal
- Frequent due to warm sea surface temperatures
Relevant Mains Points:
• Climate Change Impact on Coastal Ecosystems
- Rising sea levels and salinity threaten mangrove sustainability
- Increased frequency of extreme weather events
• Biodiversity Loss & Ecological Imbalance
- Reduced species diversity weakens ecosystem resilience
- Loss of keystone species impacts food chains
• Socio-economic Implications
- Threat to fisheries and forest-dependent communities
- Increased vulnerability to natural disasters
• Environmental Governance Challenges
- Need for transboundary cooperation (India–Bangladesh)
- Integrating climate adaptation policies
• Way Forward
- Protect mature mangrove trees to maintain resilience
- Strengthen patrolling against illegal logging
- Promote community participation in conservation
- Enhance climate-resilient policies and restoration programmes
- Improve freshwater management to control salinity
UPSC Relevance:
• GS Paper III: Environment, Climate Change, Biodiversity
• GS Paper I: Geography (Coastal Ecosystems)