World sees longest coral bleaching, says study

By Vishal Gulati

New Delhi, Jan 5 (IANS) In the past two years, the world witnessed the longest bleaching event ever recorded, which killed coral on an unprecedented scale, a latest international study says.

In India, if emissions reductions become reality the reefs would have at least 25 more years before annual bleaching -- a change in climate phenomenon -- occurs, said the study published in the journal Nature.

However, reefs near the equator will experience annual bleaching much sooner, even if emissions reduction pledges materialise, said the study, "Local-scale projections of coral reef futures and implications of the Paris Agreement".

The study was led by Ruben van Hooidonk of the University of Miami and Jeffrey Maynard.

Coral reefs in India are mostly found in the Andaman and Nicobar Islands, the Gulf of Mannar, the Gulf of Kutch and the Lakshwadeep Islands.

"These predictions are a treasure trove for those who are fighting to protect one of the world's most magnificent and important ecosystems from the ravages of climate change," an official statement quoting UN Environment head Erik Solheim said on Thursday.

"They allow conservationists and governments to prioritise the protection of reefs that may still have time to acclimatise to our warming seas. The projections show us where we still have time to act before it's too late," he said.

The researchers said if current trends continued and the world failed to reduce greenhouse gas emissions, severe bleaching would occur every year on 99 per cent of the world's reefs within the century.

The Paris Agreement's aspirational target of limiting global temperature increase to 1.5 degrees Celsius provides a safer, but not an entirely safe space for coral reefs.

Even if emission reductions exceed pledges made by countries to date under the Paris Agreement more than three quarters of the world's coral reefs would bleach every year before 2070.

The high-resolution projections, based on global climate models, in the research predict when and where annual coral bleaching would occur.

The projections show that reefs in Taiwan and around the Turks and Caicos archipelago would be among the world's first to experience annual bleaching.

Other reefs, like those off the coast of Bahrain, in Chile and in French Polynesia, would be hit decades later.

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.

"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," he added.

The need to act is clear.

Between 2014 and 2016, say the researchers, the world witnessed the longest global bleaching event ever recorded, which killed coral on an unprecedented scale.

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

The study shows that, on average, the world's reefs would start suffering annual bleaching in 2043. About five per cent of them would be hit a decade or more earlier, while about 11 per cent would 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 were 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 would have at least 25 more years before annual bleaching occurs, buying time for conservation efforts.

"It's imperative that we take these predictions seriously and that, at the very minimum, we meet the targets of the Paris Agreement. Doing so will buy time for coral reefs and allow us to plan for the future and adapt to the present," Solheim added.

(Vishal Gulati can be reached at vishal.g@ians.in)