Rising Sea Levels In Maldives, Lakshadweep, And Indian Ocean

A recent study using coral microatolls shows that sea levels around the Maldives, Lakshadweep, and Chagos Archipelago have been rising faster than previously thought, starting from the late 1950s.

Background

  • Global warming is causing thermal expansion of oceans and ice-melt, contributing to rising sea levels.
  • Low-lying island nations like the Maldives and Lakshadweep are highly vulnerable to even small increases in sea level.
  • Historical tide gauge records were limited in the central tropical Indian Ocean.

What are Coral Microatolls?

  • Coral microatolls are disk-shaped coral colonies whose upward growth stops at the lowest tide.
  • The upper surface of microatolls reflects historical lowest water levels.
  • Can live decades to centuries, preserving climate and sea-level history.
  • Scientists can extract annual growth bands similar to tree rings to reconstruct sea-level changes.

Study Details

  • Conducted at Mahutigalaa reef, Huvadhoo Atoll, Maldives.
  • Methods used:
    • Measuring and sampling coral structure.
    • X-raying slabs to study annual growth bands.
    • Uranium-thorium dating to determine historical elevation.
  • Data covered 1930–2019.

Key Findings

  • Sea level rose ~0.3 metres over 90 years in the region.
  • Rise began in the late 1950s, earlier than previous assumptions (~1990).
  • Current rate: ~4 mm/year over the last 20–30 years.
  • Historical climate events such as El Niño and negative Indian Ocean Dipole (IOD) slowed coral growth.
  • Lunar nodal cycle influenced tides and microatoll growth.
  • Tectonic stability at study sites ensured accurate sea-level reconstruction.

Implications

  • Sea level rose ~0.3 metres over 90 years in the region.
  • Rise began in the late 1950s, earlier than previous assumptions (~1990).
  • Current rate: ~4 mm/year over the last 20–30 years.
  • Historical climate events such as El Niño and negative Indian Ocean Dipole (IOD) slowed coral growth.
  • Lunar nodal cycle influenced tides and microatoll growth.
  • Tectonic stability at study sites ensured accurate sea-level reconstruction.

Conclusion:

Kilauea’s eruption highlights the dynamic nature of Earth’s geology. Studying such volcanoes not only helps in disaster preparedness but also improves understanding of plate tectonics and landform evolution.

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