Climate change will cause annual coral bleaching

Nearly all of the world’s coral reefs are at risk of experiencing severe bleaching each year by the end of this century, finds the UN’s environment agency.

The finding is part of a study funded by the UN Environment Programme (UNEP) and partners, which reviewed new climate change projections to predict which corals will be affected first and at what rate, according to a UN statement.

Researchers found that the reefs in Taiwan and the Turks and Caicos archipelago will be among the first to experience annual bleaching, followed by reefs off the coast of Bahrain, in Chile and in French Polynesia.

Calling the predictions “a treasure trove” for environmentalists, the head of the UN agency, Erik Solheim said the projects allow conservationists and governments to prioritise the protection reef protection.

“The projections show us where we still have time to act before it’s too late,” said Mr Solheim.

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.

But even if emission reductions exceed the pledges made by countries to date under the Paris Agreement, more than three quarters of the world’s reefs will bleach every year before 2070.

It takes at least five years for a reef to recover from a single bleaching event. Bleaching that takes place every year will have a deadly effect on the corals and reduce their ability to host fish or protect coasts, both of which human communities rely on, explains the study leader Dr van Hooidonk of NOAA and the University of Miami.

On average, the reefs will start to undergo annual bleaching starting in 2043, according to the study. But if emission reductions exceed the pledges 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.

Between 2014 and 2016, the world witnessed the longest global bleaching event recorded. Among the casualties was the Great Barrier Reef, with 90 per cent of it bleached and 20 per cent of the reef’s coral killed.


Image credit: U.S. Geological Survey

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