Data show seas rising faster around Maldives, Lakshadweep than believed , Pg2

Key Highlights:

• A recent study reveals that sea levels around the Maldives and Lakshadweep have been rising faster than previously estimated, with an increase of 0.3 meters over the past 90 years.
• The study, led by Paul Kench from the National University of Singapore, utilized coral microatolls to extend sea-level records in the central tropical Indian Ocean by 90 years.
• Data indicates that accelerated sea-level rise in the region began in the late 1950s, much earlier than conventional tide gauge records suggested.
• The research challenges the assumption that significant sea-level rise only started around 1990, showing a rise of approximately 3.2 mm/year since 1959 and about 4 mm/year in the last 20-30 years.

Detailed Insights:

• Coral microatolls, disk-shaped coral colonies, provide high-resolution, long-term sea-level records due to their growth being limited by the lowest tide levels.
• The study analyzed a Porites microatoll on Mahutigalaa in the Huvadhoo Atoll in the Maldives, using X-rays of coral slabs and uranium-thorium dating to determine historical sea levels from 1930 to 2019.
• Periods of slowed coral growth corresponded with major El Niño and negative Indian Ocean Dipole (IOD) events, while the 18.6-year lunar nodal cycle also influenced sea levels.
• The central Indian Ocean has experienced an earlier, more pronounced sea-level rise compared to coastal locations, driven by regional oceanic and atmospheric changes like intensified Southern Hemisphere westerlies.

Scientific/Technical Concepts Involved:

• Coral Microatolls: Disk-shaped coral colonies whose growth is limited by the lowest tide level, providing a record of sea-level changes.
• El Niño: A climate pattern describing the unusual warming of surface waters in the eastern tropical Pacific Ocean.
• Indian Ocean Dipole (IOD): An irregular oscillation of sea surface temperatures in which the western Indian Ocean becomes alternately warmer and then colder than the eastern part of the ocean.