In a dire warning about the escalating threat to the world's coral reefs, the US-based National Oceanic and Atmospheric Administration (NOAA) has revealed that nearly two-thirds of these vital marine ecosystems have experienced heat stress severe enough to trigger bleaching over the past year.
The agency's latest assessment indicates that a staggering 60.5% of the global reef area has been affected by the ongoing fourth mass bleaching event, driven by the compounding effects of climate change and the El Niño climate pattern. This figure continues to rise, surpassing the impacts of previous events in 1998, 2010, and 2014-2017.
"I am very worried about the state of the world's coral reefs," said Derek Manzello, coordinator of NOAA's Coral Reef Watch program. "We are seeing ocean temperatures play out right now that are very extreme in nature."
Coral bleaching occurs when corals expel the colorful algae living in their tissues due to heat stress, leaving them vulnerable to starvation and disease. NOAA has documented mass bleaching in at least 62 countries and territories, with India and Sri Lanka recently reporting impacts.
The situation is particularly dire in the Atlantic Ocean, where a staggering 99.7% of the basin's reefs have been subjected to bleaching-level heat stress over the past year. Manzello described the Atlantic as "off the charts" in terms of the heat stress experienced.
In the Mexican Pacific, one assessment found coral mortality ranging from 50% to 93% at Huatulco, Oaxaca. As the summer approaches, scientists anticipate further bleaching in the Southern Caribbean, around Florida, and at the Mesoamerican Barrier Reef, the world's second-largest reef system.
"This is alarming because this has never happened so early in the year before," Manzello warned, referring to the accumulating heat stress in the Southern Caribbean.
While the 2014-2017 event is still considered the worst on record due to its severity and persistence, the current crisis could soon surpass it if conditions continue to deteriorate.
With the ocean remaining anomalously hot despite the dissipating El Niño, Manzello cautioned that "it won't take much additional warming to push temperatures past the bleaching threshold."
As the world's coral reefs face an existential threat, urgent action is needed to address the root cause of this crisis – climate change driven by human activities.
