ANNOUNCEMENTS
This study presents a comprehensive analysis of blue carbon dynamics and sea level rise impacts in the Sundarbans Biosphere Reserve, India, spanning four decades (1982-2024) to assess climate change effects on the world's largest contiguous mangrove forest. Using integrated multi-temporal datasets including sea surface temperature, sea level height, tidal variations, precipitation, and land use/land cover (LULC) data, combined with the InVEST Coastal Blue Carbon model and field validation through soil organic carbon measurements, this research quantifies spatiotemporal changes in carbon storage and sequestration under multiple climate stressors. The climate analysis reveals significant environmental changes with sea surface temperatures warming at 0.178°C per decade and sea level rising at 3.89 mm/year, creating a net relative rise of 5.88 mm/year when combined with land subsidence. LULC analysis demonstrates complex landscape transformations over 30 years (1990-2020), including mangrove expansion of 126.46 km² (+7.50%), tree cover doubling to 676.61 km² (+99.77%), agricultural land decline of 607.64 km² (-25.87%), and urban expansion of 260.69 km² (+72.22%). The InVEST modeling results show substantial carbon stock growth from 1,454.79 Mt C/ha (1990) to 2,863.61 Mt C/ha (2020), representing a 96.8% increase, with projections indicating continued growth to 4,296.58 Mt C/ha by 2050. The analysis reveals declining sequestration efficiency, with carbon emissions increasing from 91.74 Mt C/ha (2005-2020) to a projected 155.98 Mt C/ha (2020-2050), reflecting accelerating conversion pressures. Sea level rise vulnerability assessment projects 20.35 km² of land submergence by 2050, resulting in 71.91 Mt C loss (1.67% of total stocks), representing 10.8% of projected net sequestration for 2020-2050. Critical thresholds are identified including sea surface temperatures >30°C during peak seasons, sea level rise >5 mm/year exceeding sediment accretion rates, and urban expansion >2%/year outpacing natural carbon accumulation. The research demonstrates that while the Sundarbans continues to function as a globally significant carbon sink with cumulative sequestration potential of 106 Mt C over 60 years (equivalent to annual emissions of medium-sized countries), the system approaches critical thresholds where climate mitigation function may be compromised. The findings provide quantitative evidence for urgent adaptive management interventions and highlight the Sundarbans' dual role as both a critical nature-based climate solution and an indicator of blue carbon system vulnerability under accelerating global change.
KEYWORDS: Blue Carbon, Sea Level Rise, Mangroves, Climate Change, Carbon Sequestration.
