Coral Fossil in Maldives Shows Sea Level Rise Sped Up Far Earlier Than Believed

Findings from study of coral skeleton reveal Indian Ocean's rise accelerated from 1959

- Shabana Begum

The Indian Ocean's sea levels began accelerating from 1959, far earlier than previously thought, according to Singapore scientists who studied a coral fossil discovered in the Maldives.

Sea levels in the central Indian Ocean rose by 30cm between 1930 and 2019. This started with an annual rise of 1.42mm since 1930, before it accelerated to 3.44mm per year from 1959. Between 1992 and 2019, it rose 4.39mm per year.

These findings were published in scientific journal Nature Communications in July.

The century-old white, chalky fossil — called a microatoll — stores the memories of the Indian Ocean.

It records sea level rise each year because its skeleton grows layer by layer sideways, similar to how trees form rings. Each layer captures details about the ocean at that time, such as temperature, salt levels, and even sea level.

Such sea level archives are valuable because most existing records are from satellite data and tide gauges that go back only to the late 20th century. Most records from the central tropical locations in the Indian Ocean date back only up to 30 years.

"What we've now got is 60 more years of sea level records, which we never had in this part of the world. The Indian Ocean basin seemed to respond quite quickly to climate change," said Professor Paul Kench from the National University of Singapore's Department of Geography.

In 2019, he led a research team from his department and Nanyang Technological University (NTU) to visit the Maldives, where they found the 2.7m-wide coral fossil, which resembles a table, and brought back a cross-section of it for study.

The microatoll resides in the shallow waters of the Maldives' Huvadhoo atoll.