A new report finds that one of the most precious ecosystems on Earth has already passed a frightening climate tipping point

At a conference in 2019, Melanie McField, a marine biologist and coral reef conservationist, was surprised by a question from an attendee: How would it feel to dedicate your life to studying an ecosystem that would be the first to be wiped off the planet?

“I’m rarely amazed,” McField, who now serves as director of the Healthy Reefs for Healthy People Initiative, told Gizmodo. Although she was well aware of the dire state of the world’s coral reefs, the idea that these ecosystems could be the first to succumb to climate change came as a troubling new realization. “I didn’t know what to say,” she said.

Today, McField is one of 160 authors of a landmark report asserting that the questioner that day may have been right. the Global Turning Points Report 2025A new study, released by the University of Exeter and international partners on Sunday, found that the world’s warm-water coral reefs have become the first terrestrial system to cross a thermal tipping point.

The report comes at the level of global ministers meet In Brazil to meet in preparation for the 30th annual UN Climate Change Conference in November. During these meetings, leaders try to reach some consensus on the major climate issues facing the planet. The report’s authors hope that their findings will help push decision-makers to take meaningful action to reduce global warming.

“We need to have stubborn people at the table in these negotiations who say: ‘We want to keep coral reefs on the planet,'” McField said.

The growing threat of ocean warming

Rising ocean temperatures are forcing many of the world’s coral reefs to expel the symbiotic algae, or zooxanthellae, that live in their tissues — a process known as coral bleaching. These algae not only give coral reefs their distinctive bright colors, but also provide them with oxygen and essential nutrients through photosynthesis.

The Earth is in the midst of the fourth global coral bleaching event, according to the British newspaper “Daily Mail”. Noah. Since January 2023, heat stress from bleaching has affected 84.4% of the world’s coral reefs, with scientists documenting mass bleaching of coral reefs in at least 83 countries and territories. This is the second event of its kind in the past ten years and the largest ever.

The good news is that bleached coral is not necessarily dead coral. If ocean temperatures return to a cooler state for an extended period of time, the algae could recolonize bleached corals. But the bad news is that climate change is increasing the severity of bleaching events while reducing the amount of recovery time between them. As a result, the prospects for coral reef recovery are rapidly diminishing.

“This is why ocean warming is scary,” Mark Hickson, a leading coral reef expert and professor of marine biology at the University of Hawaii, who was not involved in the report, told Gizmodo. “Especially now with the oceans warming so rapidly, we will see more frequent and more severe bleaching events.”

At what point does the global average temperature of Earth’s oceans become so warm that the majority of coral reefs will not be able to survive bleaching events? This is where the idea of ​​a thermal tipping point comes in. Researchers appreciation The thermal tipping point for warm-water corals is 2.16°F (1.2°C) of global surface warming above pre-industrial levels. The planet has already passed this point.

Entering uncharted waters

Crossing this threshold does not mean that all the world’s coral reefs will die tomorrow. “That’s not what we’re saying,” McField said. “We’re saying we’re in the zone where death occurs — which means the entire ecosystem is upending.”

Each reef is unique, with different species, local water temperatures, non-thermal stressors, ecosystem integrity, and levels of resilience. These and other factors shape the viability of coral reefs. But in a warming world, all coral reefs – regardless of their individual conditions and characteristics – are at greater risk.

“Let’s say we have 100 people, and they all go to the doctor,” McField said. “They all have cholesterol levels of up to 300 — which is very dangerous. They will still die at different rates.”

The report finds that global surface temperatures could rise by 2.7 degrees Fahrenheit (1.5 degrees Celsius) above pre-industrial levels over the next 10 years. This is the upper range of the thermal turning point for warm-water corals.

At that point, “we’re in new territory,” McField said. Even under the most optimistic scenario, in which global warming stabilizes at 2.7 degrees Fahrenheit without any overshoot, coral reefs in warmer waters are “almost certain” to capsize, the report states.

Where do we go from here?

Scientists around the world are working to protect and restore coral reefs. Some strategies focus on improving coral resilience through genetic modification, i.e. selectively breeding them to have resilience traits.

“This could work to some extent, to prevent the species from being lost entirely,” McField said.

“But when you think about how this could be applied at an ecosystem scale, with little money spent on on-the-ground work in coral reef countries…how would this be an economic option?”

Other strategies aim to reduce other potential stressors, such as pollution or destructive fishing practices. Hixon, for example, is working to improve water quality and protect herbivorous fish species in Hawaii, which could reduce overall stress on coral reefs and help them recover from bleaching events.

However, this work cannot mitigate all the effects of rapidly rising temperatures. The report notes that the Earth needs aggressive emissions mitigation and enhanced decarbonization to reduce global average surface temperatures to 1.8 degrees Fahrenheit (1 degree Celsius) above pre-industrial levels. “These temperatures are necessary to maintain warm-water corals on a large scale,” the report says.

“The scientific community has to engage with stakeholders of all kinds about the threats to coral reefs, how they are accelerating, and how there are some concrete steps we can take to try to save our coral reefs from loss,” Hickson said.