A bleached mound of coral

A bleached mound of coral at the Cheeca Rocks monitoring site in the Florida Keys National Marine Sanctuary that had been previously tagged shows the coral skeleton.

(Photo: NOAA AOML)

Coral Bleaching 'Off the Charts' in Atlantic as NOAA Warns Ocean Going 'Crazy Haywire'

"We had to add additional bleaching alert levels to appropriately categorize just how hot it was," said a coral reefs expert at the agency.

The phrase "off the charts" is no exaggeration in the National Oceanic and Atmospheric Administration's latest warning about a global coral bleaching event that scientists have linked to rising ocean temperatures and heat stress.

Derek Manzello, coordinator of NOAA's Coral Reef Watch Program, told reporters Thursday that about 60.5% of the world's coral reefs are now experiencing heat stress severe enough to cause bleaching, which can make the reefs more vulnerable to disease and harm the biodiversity they support.

Manzello said at the press briefing that after observing the first months of the coral bleaching event, which began in early 2023, NOAA changed its existing bleaching alert system because conditions were so abnormally warm in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea.

The agency's new bleaching alert system categorizes heat stress for coral reefs on a scale of 1-5, with Alert Level 5 representing ocean heat that could kill "approximately 80% or more of corals on a particular reef," Manzello said.

"We had to add additional bleaching alert levels to appropriately categorize just how hot it was," he said, with Level 5 "analogous to a Category 5 hurricane or cyclone."

"I hate that I have to keep using that word 'unprecedented.'... But, again, we are seeing unprecedented patterns again this year."

The world's oceans, Manzello, said, are going "crazy haywire."

In the Caribbean this year, heat stress off the coasts of Panama, Costa Rica, Nicaragua, and Colombia are now at levels that in previous years weren't seen until the summer months.

"I hate that I have to keep using that word 'unprecedented,'" Manzello toldThe New York Times. "But, again, we are seeing unprecedented patterns again this year."

The bleaching that took place last year resulted in coral mortality of at least 50% and as high as 93% in reefs off the coast of Huatulco, Mexico, according to a team of Mexican scientists.

In the Atlantic, fossil fuel-driven planetary heating has been exacerbated by El Niño—the natural phenomenon that causes warmer-than-normal ocean surface temperatures—and has caused the "most unprecedented and extreme" bleaching-level heat stress observed in the past year.

Manzello said 99.7% of reef areas in the Atlantic have experienced heat stress that could cause bleaching.

"The Atlantic Ocean has been off the charts," he said.

Scientists have recorded four global bleaching events since 1998 and have linked all of them to warmer ocean temperatures. Since 1950, the world has lost half of its coral reefs, according to a 2021 study.

Along with serving marine life, a quarter of which rely on coral reefs at some point in their life cycles, reefs also protect coasts from storms, whose growing severity in recent years scientists have also linked to planetary heating.

The current bleaching event has affected reefs off the coasts of at least 62 countries and territories.

Scientists earlier this year confirmed that 2023 was the hottest year in human history and the warmest year on record for the world's oceans, which absorb more than 90% of excess heat from greenhouse gas emissions.

"I am very worried about the state of the world's coral reefs," Manzello said. "We are seeing [ocean temperatures] play out right now that are very extreme in nature."

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