Corals may vanish if temperatures continue to rise

Lakshadweep islands will be the first where the reefs may disappear

Corals may vanish if temperatures continue to rise


Into the blue: Coral reefs are the world’s most diverse marine habitat, supporting an estimated five lakh species globally.

Lakshadweep will be the first place where corals may die followed by the Andaman and Nicobar islands as well as the Gulf of Mannar. The Gulf of Kachchh may sustain corals for a few decades more, but eventually they, too, will perish.

The warnings have come from researchers at the Central Marine Fisheries Research Institute, Kochi. They analysed coral vulnerability, assuming that the sea surface temperature will rise by 3 degrees Celsius between 2000 and 2099.

The temperature forecast came from one of the latest weather models used by the UK Meteorological Organisation. Satellite data from a US payload was used to validate the temperature projection.

According to the study, unless immediate action is taken to limit temperature rise, bleaching—whitening of corals due to external stress—will become an annual or biannual phenomenon in almost all reef regions along the Indian coast in the next 30-50 years.

Reef building corals may lose their dominance between 2030 and 2040 in the Lakshadweep and between 2050 and 2070 in another four regions, the team reported in the journal Current Science. Coral reefs are the world’s most diverse marine habitat, supporting an estimated five lakh species globally. They are among the most sensitive of all ecosystems to temperature changes, resulting in bleaching. Though corals usually recover, they die in extreme cases. Also an increased frequency of bleaching reduces their capacity to recover.

Coral bleaching

The scientists found thermal thresholds for coral bleaching in all the five regions are exceeded frequently until the middle of this century and almost every year after 2050. Between 2000 and 2099, sea surface temperature in the Lakshadweep is projected to rise from 29.2 degrees to 32.2 degrees Celsius. In the Gulf of Kachchh it may rise from 27 degrees to 30.5 degrees Celsius.

The bleaching trend in the Lakshadweep islands may set in as early as by 2030 followed by the Andaman and Nicobar islands. It may even happen early if other factors like acidification of the ocean and El Nino events are taken into account.

By 2050, catastrophic exposure to temperature is the most likely outcome. Given that partial recovery time for such an event is at least 10 years and 50 years for full recovery, this could mean a non-coral-dominated reef structure in the Lakshadweep.

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