by Coral reefs around the world are experiencing a predicted mass bleaching event as the climate crisis drives record ocean warming, two scientific bodies announced on Monday – with some experts warning that this could be the worst bleaching period in recorded history.
More than 54% of the world’s coral reef areas have experienced bleaching in the past year, affecting at least 53 countries and territories, including major reefs in the Atlantic, Pacific and Indian Oceans, a statement joint from the National Oceanic and Atmospheric Administration (NOAA). ) and the International Coral Reef Initiative (ICRI).
“This event will likely exceed the previous peak of 56.1% soon,” Derek Manzello, coordinator of NOAA’s Coral Reef Watch program, said in an email to CNN. “The percentage of reef areas experiencing heat stress at a predicted level is increasing by about 1% per week.”
When corals are exposed to stress from ocean heat waves, they uproot the algae that live within their tissues, which provide them with their color and most of their energy. If ocean temperatures do not return to normal, bleaching can lead to mass die-off of corals, threatening the collapse of species and the food chains that depend on them.
This is the fourth global bleaching event in the world, and the second in the last decade – with previous periods in 1998, 2010, and between 2014-2017.
Over the past year, mass bleaching has been confirmed in regions including Florida and the wider Caribbean, Mexico, Brazil, Australia, the South Pacific, the Red Sea, the Persian Gulf, Indonesia, and the Ocean Indian including the east coast of Africa and the Seychelles.
Professor Ove Hoegh-Guldberg, a climate scientist specializing in coral reefs based at the University of Queensland in Australia, predicted this mass bleaching event months ago.
“We knew that ocean temperatures were increasing quickly, but not at this speed,” Hoegh-Guldberg told CNN on Monday. “The worst question is that we don’t know how long this huge temperature change will last.”
The last 12 months have been the hottest on record on the planet and sea temperatures are soaring off the charts. Global sea surface temperatures hit record highs in February and again in March, according to data from the European Commission’s Copernicus Climate Change Service.
In February, scientists at NOAA’s Coral Reef Watch program added three new alert levels to the coral bleaching alert maps, to enable scientists to assess the new scale of underwater warming.
Will La Niña bring relief?
El Niño, a natural climate pattern that originates in the equatorial Pacific Ocean and tends to raise global temperatures, helped drive unprecedented ocean warming.
NOAA is predicting that La Niña, El Niño’s cooler counterpart, could set in between June and August of this year, giving coral reefs “a boost of hope,” NOAA’s Manzello said.
But, he said, bleaching events have still occurred during La Niña in recent years.
“I’m getting more and more worried about the summer of 2024 for the Caribbean and Florida more broadly,” Manzello said. “As we roll into summer and bleaching season for Florida and the Caribbean, it won’t take much additional seasonal warming to push temperatures over the bleaching threshold.”
In mid-February, CNN witnessed widespread coral bleaching on Australia’s Great Barrier Reef – the world’s largest coral reef system – on five different reefs spanning the northern and southern areas. A mass bleaching event was officially confirmed last month following aerial and underwater surveys by the Australian Institute of Marine Science (AIMS) and the Great Barrier Reef Marine Park Authority.
“The tolerance levels of coral reefs are being tested by the increased frequency and severity of marine heat waves driven by climate change,” said AIMS CEO Selina Stead. “Climate change is the biggest threat to coral reefs around the world and this global confirmation shows just how far-reaching its impact has been over the past 12 months.”
“That’s why it’s critical that the world works to reduce carbon emissions,” Stead said. “It is also important to ensure that coral reefs are well managed at local and regional levels.”
The United Nations Environment Program has warned that if the world fails to aggressively lower its emissions, the planet is headed for nearly 3 degrees Celsius of warming above pre-industrial levels this century.
Scientists predict that even at 2 degrees of warming – which the world could reach around 2050 – around 99% of the world’s corals would die.
As well as being an essential habitat for marine life, coral reefs are vital to the world’s coastal communities — they act as a critical defense system against the threat of flooding from storms and sea level rise, and provide a vital livelihood and food source also available. around a billion people worldwide.
David Ritter, CEO of Greenpeace Australia, said that reefs were facing “grave danger” and that the blame “lies heavily on the main culprits who drive global warming: fossil fuel companies, and the governments that support this industry.” “
“We are running off the runway to avoid an irreversible climate catastrophe,” he said, “and we must act quickly to ensure an immediate end to new fossil fuels.”
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