`World witnessed longest bleaching event in past two years`

Washington: The world witnessed the longest global coral bleaching event ever recorded between 2014 and 2016, which killed corals on an unprecedented scale, according to new global study which found that reefs in India will have at least 25 more years before annual bleaching occurs.

In 2016, bleaching hit 90 per cent of coral on the iconic Great Barrier Reef and killed more than 20 per cent of the reef's coral, researchers said.

The new climate model projections of the world's coral reefs shows which reefs will be hit first by annual coral bleaching, an event that poses the gravest threat to one of the Earth's most important ecosystems.

Researchers from University of Miami in the US projected that reefs in Taiwan and around the Turks and Caicos archipelago will be among the world's first to experience annual bleaching.

If current trends continue and the world fails to reduce greenhouse gas emissions, then severe bleaching will occur every year on 99 per cent of the world's reefs within the century, according to the study.

It takes at least five years for a reef to recover from a single bleaching event.

"Bleaching that takes place every year will invariably cause major changes in the ecological function of coral reef ecosystems," said study leader van Hooidonk from the University of Miami.

"Further, annual bleaching will greatly reduce the capacity of coral reefs to provide goods and services, such as fisheries and coastal protection, to human communities," said Hooidonk.

The study shows that, on average, the world's reefs will start suffering annual bleaching in 2043.

About 5 per cent of them will be hit a decade or more earlier, while about 11 per cent will suffer annual bleaching a decade or more later than this date.

If emission reductions exceed pledges made by countries to date under the Paris Agreement, coral reefs would have another 11 years, on average, to adapt to warming seas before they are hit by annual bleaching.

If such emissions reductions become reality, many high and low latitude reefs in Australia, the south Pacific, India, Coral Triangle and the Florida Reef Tract will have at least 25 more years before annual bleaching occurs, buying time for conservation efforts.

However, reefs near the equator will experience annual bleaching much sooner, even if emissions reductions pledges become reality, researchers said.