Coral catastrophe

Consistent ocean heating puts global corals at risk of mass bleaching in 2024

- AKSHIT SANGOMLA

IN EARLY March, scientists in Australia confirmed that the Great Barrier Reef, the world's largest coral reef system, is undergoing mass bleaching. This is the fifth such event at the UNESCO World Heritage Site since 2016, which scientists attribute to ocean warming. "We have a fair idea from satellites that the heat stress in the southern Great Barrier Reef is as bad as it has ever been,” David Wachenfeld, research program director, Reef Ecology and Monitoring Program, Australian Institute of Marine Science, tells Down To Earth (dte).

Found majorly in tropical and sub-tropical oceans all across the world, coral reefs are complex underwater ecosystems that sustain 25 per cent of all marine species. They also provide millions of dollars in terms of ecosystem services and tourism. In a warming world, these ecosystems are threatened due the frequent and severe coral bleaching. During such an event, algae growing on hard shells of corals die due to heat stress, ocean acidification or other factors, stripping colour from corals and making them vulnerable to diseases. Not just the Great Barrier Reef, but “unprecedented” mass coral bleaching and mortality are likely across the Indo-Pacific region in 2024, says a December 2023 Science paper that analyses sea surface temperatures over the past 40 years.

For example, coral bleaching in the Indian Ocean region may start in April and May, Roxy Mathew Koll, climate scientist at the Indian Institute of Tropical Meteorology, Pune, tells dte. In the Indian Ocean region, the Gulf of Kutch in Gujarat, Gulf of Mannar in Tamil Nadu, Andaman and Nicobar, and Lakshadweep islands have coral reefs.