Sea-Level Rise in Maldives & Lakshadweep – New Findings from Coral Microatolls
Context
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A new study (led by Paul Kench, NUS) using coral microatolls has extended sea-level records in the central Indian Ocean by 90 years.
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Findings: Seas around Maldives, Lakshadweep, Chagos have been rising faster and earlier than previously assumed.
About Coral Microatolls
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Disk-shaped coral colonies → upward growth limited by lowest tide level.
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Act as natural sea-level markers since their surface reflects lowest water levels over time.
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Can live for decades–centuries; growth bands similar to tree rings.
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Useful in data-sparse regions → provide long-term sea-level history.
Key Findings of the Study
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Location: Mahutigalaa reef platform, Huvadhoo Atoll, Maldives.
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Period reconstructed: 1930–2019.
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Sea-level rise (SLR): ~0.3 m over 90 years.
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Rates of SLR:
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1930–1959 → 1–1.84 mm/yr
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1960–1992 → 2.76–4.12 mm/yr
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1990–2019 → 3.91–4.87 mm/yr
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Major revelation:
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Acceleration began late 1950s (not ~1990 as commonly believed).
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Since 1959: ~3.2 mm/yr, rising to ~4 mm/yr in last 20–30 years.
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Total rise over 50–60 years: 30–40 cm.
Wider Implications
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Maldives, Lakshadweep & Chagos → among world’s most vulnerable islands.
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Sea-level rise threatens → coral reefs, coastal ecosystems, communities & infrastructure.
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Challenges adaptation models that assumed significant SLR only after 1990.
Additional Insights from Coral Records
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El Niño & Negative IOD events → linked to slowed coral growth & bleaching.
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18.6-year lunar nodal cycle → influences tides & sea levels.
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Tectonic stability of study site ensured data reliability.
Why Indian Ocean is Critical
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SLR in Indian Ocean: ~3.3 mm/yr, above global average.
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Region also warming faster than global average → amplifies bleaching, circulation shifts, and extreme events.
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Regional drivers:
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Intensified Southern Hemisphere westerlies.
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Increased ocean heat uptake.
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Possible shifts in ITCZ (Inter-Tropical Convergence Zone).
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Significance of the Study
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Fills data gaps in central Indian Ocean (least monitored basin).
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Offers historical context to refine SLR projections.
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Critical for climate adaptation planning in island nations.
UPSC Relevance
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GS-1 (Geography): Sea-level rise, coral reefs, climate change.
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GS-3 (Environment & Disaster Mgmt): Vulnerability of small island states, Indian Ocean dynamics.
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Essay: “Rising seas and sinking shores: the climate crisis in small island nations.”
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Prelims Pointers: Coral microatolls, Indian Ocean warming, El Niño & IOD linkages.
Way Forward
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Expand long-term monitoring (satellite + tide gauges + coral proxies).
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Strengthen adaptation measures for Lakshadweep & Maldives.
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Global cooperation for climate finance & resilience.
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Integration of indigenous knowledge + scientific data for coastal planning.
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