Scientists say massive bleaching is occurring on coral reefs around the world | Climate News

Scientists have warned that many of the world’s coral reefs may not be able to recover from prolonged and severe heat stress.

Along coastlines from Australia to Kenya to Mexico, many of the world’s colorful coral reefs are turning ghostly white, scientists say, marking the fourth global bleaching event in the past 30 years. He says he will.

The world’s largest coral reef monitoring organization, the National Oceanic and Atmospheric Administration (NOAA), said that as ocean surface waters warm due to climate change, the world’s largest coral reef monitoring organization will continue to operate along coral reefs in at least 54 countries and territories since February 2023. It was announced on Monday that a large-scale bleaching event was occurring.

“Significant coral bleaching has been recorded in both the northern and southern hemispheres in major ocean basins from February 2023 to April 2024,” Coral Reef Watch coordinator Derek Manzello told reporters. Told.

Corals are invertebrates that live in colonies. Calcium carbonate secretions form a hard, protective scaffold that serves as a home for many colorful unicellular algae.

Coral bleaching is caused by abnormal water temperatures that cause corals to expel the colorful algae that live within their tissues. Without the help of algae, which deliver nutrients to corals, corals cannot survive.

“More than 54 percent of the world’s oceanic coral reef areas are exposed to bleaching-level heat stress,” Manzello said.

Coral reefs bleaching on Australia’s Great Barrier Reef; scientists conduct underwater monitoring during ocean heat at Moore Reef [Grace Frank/Australian Institute of Marine Science/Handout via Reuters]

Like this year’s bleaching event, the previous three bleaching events (1998, 2010, and 2014-2017) coincided with El Niño weather patterns, which typically result in warmer ocean temperatures.

Sea surface temperatures over the past year broke records that had been held since 1979, as the effects of El Niño are exacerbated by climate change.

Second, Australia’s Great Barrier Reef, the world’s largest and only coral reef visible from space, is severely affected, as are large swaths of the South Pacific, Red Sea and Gulf.

“We know the biggest threat to coral reefs around the world is climate change, and the Great Barrier Reef is no exception,” Australian Environment Minister Tanya Plibersek said last month.

Last August, coral reefs in the Caribbean experienced widespread bleaching as coastal sea surface temperatures hovered between 1 and 3 degrees Celsius (1.8 to 5.4 degrees Fahrenheit) above normal.

Scientists working in the area then began documenting mass die-offs across the region. Lorenzo Álvarez Philippe, a marine ecologist at the National Autonomous University of Mexico, told Reuters that “in some reefs, everything you see while diving was white,” from giant stag beetles to brain corals.

“I’ve never seen this level of bleaching.”

At the end of the austral summer in March, tropical coral reefs in the Pacific and Indian Oceans also began to suffer.

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A colony of Diplolia labyrintiformis shows tissue loss due to disease near the University of the Virgin Islands campus in St. Thomas, U.S. Virgin Islands. [File: Lucas Jackson/Reuters]

Scientists have warned that many of the world’s coral reefs may not be able to recover from prolonged and intense heat stress.

“What’s happening is new for us and for science,” Alvarez-Philippe said.

“Even if severely stressed corals survive the immediate heat stress, we still cannot predict the extent to which they will be affected,” he added.

Repeated bleaching events also predict that 70% to 90% of the world’s coral reefs could be lost if global warming reaches 1.5 degrees Celsius (2.7°F) above pre-industrial temperatures. It is trying to overturn the previous scientific model. To date, the world has warmed by about 1.2 degrees Celsius (2.2 degrees Celsius).

In a 2022 report by the United Nations Intergovernmental Panel on Climate Change, experts determined that just 1.2°C (2.2°F) of warming would be enough to seriously impact coral reefs, and that “Most of the available evidence suggests that coral-dominated ecosystems will no longer exist.” At this temperature. ”

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Divers swim over dead coral off Malaysia’s Tioman Island in the South China Sea. [File: David Loh/Reuters]

This year’s global bleaching event has added to scientists’ concerns that corals are in grave danger.

“The realistic interpretation is that we have crossed the tipping point for coral reefs,” David Obura, an ecologist in Mombasa, Kenya, who leads the Indian Ocean East Africa Coastal Marine Research and Development, told Reuters. .

“Unless we truly stop carbon dioxide emissions,” which are causing climate change, Koura said, “we are in such a decline that we cannot stop them.”

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