NEWS – Rising Seas Around Maldives and Lakshadweep: New Findings

HIGHLIGHTS

Background

• Sea-level rise is a major impact of global warming, threatening low-lying islands.
• Coral reefs, sensitive to water levels, face bleaching when sunlight penetration reduces.
• Monitoring in Indian Ocean began with Tropical Ocean Global Atmosphere Programme (1985-94), later under Global Sea Level Observing System.

Study Methodology

• Conducted on Mahutigalaa reef, Maldives, led by Paul Kench (National University of Singapore).
• Used coral microatolls (disk-shaped corals limited by lowest tide) as natural sea-level markers.
• Microatoll growth bands (like tree rings) + Uranium-Thorium dating used to reconstruct 90 years (1930–2019) of sea-level history.
• Site tectonically stable, ensuring reliability of sea-level inference.

Key Findings

• Total rise: ~0.3 metres (30–40 cm) over 90 years.
• Rates of rise:
  • 1930–59: 1–1.84 mm/year
  • 1960–92: 2.76–4.12 mm/year
  • 1990–2019: 3.91–4.87 mm/year
• Rise began late 1950s, earlier than previously assumed (1990s).
• Current rate ~4 mm/year, higher than global average (3.3 mm/year).

Regional Implications

• Maldives, Lakshadweep, Chagos have been exposed to steady rise for 60+ years.
• Amplified by ocean warming, altered currents, El Niño, negative IOD events.
• Coral growth interruptions aligned with climatic stress events; also reflected 18.6-year lunar nodal cycle.

Significance

• Challenges assumption that sea-level rise began only in 1990.
• Highlights regional variations in Indian Ocean: earlier, more pronounced rise in central basin.
• Provides historical baseline for adaptation planning in vulnerable island nations.
• Microatolls as tool: Complementary to tide gauges/satellites, crucial for data-sparse regions.