1st September 2025 (15 Topics)
1
Sep
Rising Seas and Coral Reefs
Context:
A recent study using coral microatolls in the Maldives has reconstructed sea-level history over 90 years, showing that sea-level rise in the Indian Ocean began as early as the late 1950s, much earlier than previously believed.
Key Dimensions of the Issue
Sea-Level Rise in the Indian Ocean
- Indian Ocean average rise: ~3.3 mm/year, higher than the global average.
- Total increase over the last half-century: 30–40 cm.
- Acceleration observed:
- 1930–1959: 1–1.84 mm/year.
- 1960–1992: 2.76–4.12 mm/year.
- 1990–2019: 3.91–4.87 mm/year.
Coral Reefs and Vulnerability
- Sunlight dependency: Rise in sea level reduces light penetration ? coral bleaching.
- Stress factors: Ocean warming, acidification, changing tides, and coastal erosion.
- Coral bleaching linked to El Niño and negative Indian Ocean Dipole (IOD)
Use of Coral Microatolls in Research
- Definition: Disk-shaped coral colonies growing sideways when vertical growth is restricted by tide levels.
- Serve as natural recorders of sea-level variations.
- Research method: Uranium-thorium dating + growth band analysis (like tree rings).
- Advantage: Provide long-term, high-resolution sea-level records in tectonically stable areas.
Findings of the Study
- Sea-level rise began decades earlier than tide-gauge records suggested.
- Regional differences:
- Central Indian Ocean: Earlier, stronger acceleration.
- Coastal Indian Ocean: More recent acceleration.
- Drivers: Oceanic and atmospheric changes (e.g., intensified Southern Hemisphere westerlies, increased ocean heat uptake, shifts in ITCZ).
Implications for Island Nations
- Nations at risk: Maldives, Lakshadweep, Chagos archipelago.
- Risks: Submergence of land, loss of biodiversity, damage to infrastructure, displacement of populations.
- Importance of historical reconstruction: Enables better climate adaptation planning.
Way Forward:
- Expand monitoring using coral microatolls across the Indian Ocean basin.
- Enhance adaptation strategies for vulnerable island nations through coastal protection and relocation planning.
- Strengthen international cooperation on climate finance and technology transfer for resilience building.
- Integrate regional sea-level histories into IPCC models for improved projections.
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