Less than two years after researchers at the University of Exeter warned that the world was nearing multiple climate tipping points, a new international report has confirmed that one of those irreversible thresholds has already been crossed. The planet, scientists say, has reached its first major climate tipping point with the dieback of warm-water coral reefs—ecosystems that once supported nearly a million species of marine life and shielded coastal communities from storms and erosion.
According to the 2025 Global Tipping Points Report, released Monday, “the central estimate of coral reefs’ tipping point of 1.2°C global warming has been crossed,” with global average temperatures now roughly 1.4°C above preindustrial levels. Since 2023, the world’s reefs have experienced the worst mass bleaching event on record, with more than 84 percent of reefs impacted by extreme ocean heat.
“We can no longer talk about tipping points as a future risk,” said Steve Smith, a social scientist at the University of Exeter and a lead author of the report. “This is our new reality.”
The scale of reef die-off is without precedent. “We have now pushed (coral reefs) beyond what they can cope with,” said Mike Barrett, chief scientific adviser at the World Wide Fund for Nature in the UK and co-author of the report. “Unless global warming is reversed extensive reefs as we know them will be lost.”
Bleaching occurs when prolonged heat stress causes coral to expel symbiotic algae, turning once-colorful reefs into ghostly white structures. Many corals can recover from short bleaching events, but repeated exposure and rising baseline temperatures make recovery increasingly unlikely.
The report notes that maintaining reefs “at any meaningful scale” will require not only halting warming but actively reducing global temperatures. “Unless we return to global mean surface temperatures of 1.2°C (and eventually to at least 1°C) as fast as possible, we will not retain warm-water reefs on our planet at any meaningful scale,” it states. “Minimizing non-climatic stressors, particularly improved reef management, can give reefs the best chance of surviving under what must be a minimal exceedance of their thermal tipping point.”
Coral reefs are among the most biodiverse ecosystems on Earth, providing food and habitat for nearly a million species and forming the foundation of marine life in tropical oceans. Their loss is expected to trigger cascading impacts: the collapse of reef-dependent fisheries, coastal exposure to storm surge, and a sharp decline in tourism industries worth billions of dollars each year.
“The impacts will have far-reaching consequences,” the report warns. “Coral reefs are an essential habitat for marine species, vital for food security, contribute trillions to the global economy and buffer coastal areas from storms.”
Bleaching events have transformed once vibrant reefs into what the report calls “a seaweed-dominated landscape.” The ecological shift from coral to algae not only diminishes biodiversity but undermines the carbon storage capacity of ocean ecosystems already under stress.
Warm-water reefs are only the first domino. The report cautions that Earth is now “rapidly approaching multiple Earth system tipping points that could transform our world, with devastating consequences for people and nature,” according to Tim Lenton, a professor at the University of Exeter’s Global Systems Institute.
Among the tipping points scientists say are drawing near are the large-scale degradation of the Amazon rainforest, the melting of mountain glaciers such as Áakʼw Tá Hít in Alaska, and the potential collapse of the Atlantic Meridional Overturning Circulation (AMOC)—a vast ocean current that regulates climate by moving warm water from the tropics to the northern Atlantic.
“There is now a risk that collapse could occur within the lifetime of people born and living on the planet today,” said Barrett, referring to the AMOC. Such a collapse could have catastrophic global consequences, disrupting monsoon systems, driving extreme heat in some regions, and plunging others into sudden cold.
Without rapid cuts in greenhouse gas emissions, scientists warn that the world will surpass 1.5°C of warming within the next decade. “We are going to overshoot 1.5°C of global warming probably around 2030 on current projections,” Lenton told The Guardian. The report calls for “immediate, significant reductions in fossil fuel emissions” to bring the global mean surface temperature back down toward 1.2°C and eventually to 1.0°C.
However, some scientists say the opportunity to reverse coral loss may already be gone. “We won’t reduce temps to 1.2°C as soon as possible, so this is the death knell for most of the world’s stupendous reef communities,” said Bill McGuire, a climate scientist quoted in the report. “Other tipping points will follow.”
The authors stress that current global governance frameworks are not equipped for such abrupt, irreversible changes. “Current policies and international agreements are designed for gradual changes, not for these kinds of abrupt, irreversible and interconnected shifts,” said Manjana Milkoreit, a political scientist at the University of Oslo and a co-author of the report. “We have the knowledge regarding how to stop the Earth from reaching more tipping points. What we need is a kind of governance that matches the nature of this challenge.”
The 2025 report also outlines potential “positive tipping points”—self-reinforcing changes that can accelerate climate progress, such as the rapid growth of renewable energy. “Solar PV panels have dropped in price by a quarter for each doubling of their installed capacity. Batteries have improved in quality and plummeted in price the more that are deployed,” the report notes. “This encourages further adoption. The spread of climate litigation cases and nature positive initiatives is also self-amplifying. The more people undertaking them the more they influence others to act.”
“The race is on to bring forward these positive tipping points to avoid what we are now sure will be the unmanageable consequences of further tipping points in the Earth system,” said Lenton.
The findings come just weeks before global leaders meet in Belém, Brazil for the 30th Conference of the Parties (COP30) to the United Nations Framework Convention on Climate Change. The meeting will center on how to deliver a “Granary of Solutions”—a framework for scaling up existing technologies and policy tools that can drive down emissions fast enough to trigger systemic change.
“As we head into the COP30 climate negotiations it’s vital that all parties grasp the gravity of the situation,” said Mike Barrett to Yale Environment 360. “Countries must show the political bravery and leadership to work together and achieve them.”
The urgency of such cooperation is underscored by diverging national trajectories. The report highlights rapid progress in renewable adoption across much of the world—but notes that the United States, under President Donald Trump, has moved in the opposite direction. A recent spending bill “imposes new fees on solar and wind development and boosts drilling on public lands while the U.S. Department of Energy is investing $625 million in coal.”
The crossing of the coral reef tipping point is both an ecological tragedy and a warning of what lies ahead. It reveals the cascading fragility of Earth’s interconnected systems and the accelerating pace of irreversible change. For the scientists behind the Global Tipping Points Report, the message is stark: the time for hypothetical scenarios has ended.
As Lenton said, “We are rapidly approaching multiple Earth system tipping points that could transform our world, with devastating consequences for people and nature.”
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