Extreme ocean heat is causing a mass bleaching event in coral reefs around the world, according to the National Oceanic and Atmospheric Administration.
NOAA declared on Monday that a “fourth global coral bleaching event” was occurring and that bleaching had been documented over the past 14 months in all major ocean basins, including off Florida, the United States, the Great Australian Barrier Reef and the South Pacific.
“As the world’s oceans continue to warm, coral bleaching is becoming more frequent and severe,” said Derek Manzello, a coral reef ecologist who coordinates NOAA’s Coral Reef Observation Program, in a statement from press. “When these events are severe or prolonged enough, they can cause coral mortality, which harms people who depend on coral reefs for their livelihoods.”
Sea surface temperatures have set daily records for over a year, which has raised concerns among scientists trying to figure out how the oceans got so hot so quickly. Warming due to climate change and cycles of natural variability, such as El Niño, have played a significant role.
Coral health is interconnected with ocean temperatures because invertebrates are extremely sensitive to thermal stress. When corals are stressed, they turn white as they release symbiotic algae that live in your tissues. Bleaching is a sign that coral health is in danger.
“When coral bleaches, it doesn’t mean it’s dead. It means it is weak and at risk of dying if conditions don’t improve,” said Ana Palacio, assistant scientist at the Cooperative Institute for Marine and Atmospheric Studies, a research institute based at the University of Miami in partnership with NOAA. .
Corals are critical ecosystems that support a wide range of fish and aquatic species, which help feed coastal communities and attract tourists. The economic value of reefs is estimated at 2.7 billion dollars per year, according to a 2020 report by the Global Coral Reef Monitoring Network.
“They protect our coastline. They offer protection from storms and hurricanes. They have great value for our economy and security,” said Palacio.
Coral ecosystems are among the ecosystems that scientists consider to be most at risk from global warming. In 2018, the United Nations Intergovernmental Panel on Climate Change estimated that 70% to 90% of the world’s coral reefs would disappear if global average temperatures exceeded the limit of 1.5 degrees Celsius above the pre-industrial average.
Last year was the hottest ever recorded on Earth. Average global temperatures got closer to it threshold for the first time, although scientists believe temperatures were raised by El Niño and that 2023 was an anomaly.
In Florida, as sea surface temperatures rose, bleaching began early in the season, experts said.
“Typically, bleaching will be observed in the Northern Hemisphere around August and September. We started seeing bleaching in July last year,” said Phanor Montoya-Maya, a marine biologist at the Coral Restoration Foundation, an organization that collects, restores and repopulates corals.
Palacio said the region has seen widespread mortality of elkhorn and staghorn corals, two species that have been the focus of restoration efforts.
“In some locations, around 20% of these populations have survived,” Palacio said of the restored corals. “We are focusing our hope on why these corals survived and what they can tell us about resilience and how corals can be more resilient.”
The latest global coral bleaching event happened in 2014 and lasted until 2017. More than 56% of global reef areas experienced temperatures that could cause bleaching during that period.
In an email Monday, Manzello said that 54% of the world’s coral reef areas experienced bleaching-level heat stress last year and that the event was poised to become the worst bleaching event in history.
“The percentage of reef areas experiencing bleaching-level heat stress has been increasing by about 1% per week,” Manzello said. “This event is likely to exceed the previous peak.”
Montoya-Maya said a bleaching warning is already in effect in Florida, even before last year. He said the Coral Restoration Foundation was preparing for a busy summer in response to another bleaching event.
The natural pattern of El Niño has begun to dissipate and NOAA’s Climate Prediction Center estimates that there is a 60% chance of La Niña developing this summerwhich could help cool Atlantic waters and allow some corals to recover, at least temporarily.
“This is very painful and will cause damage to many reefs around the world,” Palacio said. “I hope this bleaching event creates some traction and that people start to care more and pay attention to what is happening with the climate.”
This article was originally published in NBCNews. with
