NEW YORK, United States, Thursday January 12, 2017 – New climate model projections of the world’s coral reefs reveal 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.
These high-resolution projections, based on global climate models, predict when and where annual coral bleaching will occur. The projections show that reefs in Taiwan and around the Turks and Caicos archipelago will 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, will be hit decades later, according to research recently published in the journal Nature Scientific Reports.
“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,” said Erik Solheim, head of UN Environment.
“They allow conservationists and governments to prioritize the protection of reefs that may still have time to acclimatize to our warming seas. The projections show us where we still have time to act before it’s too late.”
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.
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 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 invariably cause major changes in the ecological function of coral reef ecosystems,” said study leader Dr. van Hooidonk of NOAA and 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.”
The need to act is clear. Between 2014 and 2016, 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.
Coral reefs, which are already under threat from overfishing and tourism, are especially vulnerable to climate change because they are easily affected by warm water. When sea temperatures rise, the algae that give coral its bright colours leave their host, causing it to look white, hence the term ‘coral bleaching’. The loss of algae, which provide coral with much of its energy, make corals vulnerable to starvation and disease.