Coral reefs are at a tipping point after surging global temperatures

A recent surge in ocean temperatures has led to widespread bleaching and mortality of warm-water corals around the world, officially triggering the first… climate This is a turning point for one of the Earth's ecosystems, scientists said.

The collapse of one of the world's most diverse and fragile ecosystems poses a “threat to human health and safety” that governments are unprepared for, warns Melanie McField at the Smithsonian Institution's Healthy Reefs for Healthy People program in Florida.

Warm water coral reefs support up to one third of all known marine biodiversity and provide food, coastal protection and income for up to a billion people worldwide. Reef services contribute up to $9.9 trillion annually to goods and services worldwide.

However, corals are very sensitive to changes in water temperature. Record global temperatures recorded since 2023 have pushed Ocean heat levels reach new highwhich caused a massive bleaching event that affected more than 80 percent of all corals in the world. Bleaching is when corals expel algae living in their tissues in response to high water temperatures, causing them to turn white. This makes the corals vulnerable to disease, and long-term bleaching can completely destroy them, depriving them of their main food source.

The latest bleaching event was “an order of magnitude different” from anything scientists had seen before, McField said. “We are at a tipping point,” she confirms. This is generally defined as a critical threshold that, if exceeded, could cause dramatic and likely irreversible changes in the climate system.

McField was one of the authors of the chapter on corals in Global Tipping Points 2025 Report.released today. The report, the first update since 2023, was compiled by 160 scientists from around the world and coordinated by the University of Exeter in the UK and the WWF research group. He warns that warm-water corals are the first Earth system to cross a tipping point and are now facing an “unprecedented crisis.”

Central academic estimates indicate that the thermal limit of warm-water corals is reached when global atmospheric temperatures reach 1.2°C above pre-industrial levels, with an upper threshold of 1.5°C. In 2024, average global temperatures temperatures exceeded pre-industrial levels by 1.5°C for the first time in human history.an event that pushed the world's coral reefs beyond their endurance limits, according to Tim Lenton at the University of Exeter, who led the report.

“We took the example of global warming of 1.5°C and saw the consequences,” he told reporters at a briefing ahead of the report's release. “Most coral reefs are at risk of widespread extinction. [or bleaching] and transition to an alternative state where seaweed dominates and is covered with algae.”

The best hope for saving the world's warm-water corals from near extinction now lies in rapidly reducing average global temperatures to 1.2°C above pre-industrial levels, he said. Whether such an ambitious target, which goes far beyond the requirements of even the 1.5°C temperature target, can be achieved is a separate question, Lenton says.

Terry Hughes James Cook University in Australia warns that there are now “hardly any unbleached reefs left in the world.” But the situation can still be mitigated. “Where coral reefs end up in the next few decades is within our control if global greenhouse gas emissions are quickly reduced,” he says.

The point at which climate tipping points may occur is often highly uncertain, but researchers warn that widespread decline of the Amazon rainforest, melting of polar ice sheets And collapse of the crucial ocean current AMOC all of this could happen with warming below 2°C.

But people can also drive “positive tipping points” to reduce risk, Lenton emphasizes, highlighting the exponential growth of renewable energy over the past decade and the rapid adoption of electric vehicles. The report notes that rapid adoption of cleaner technologies could achieve emissions reductions on the scale needed to keep warming below 2°C.

In a statement, Lenton said urgent action was needed from world leaders at the upcoming conference. KS30 summit in Brazil to accelerate emissions reductions in the global economy and minimize the amount of time global temperatures exceed 1.5°C. “We are rapidly approaching multiple Earth system tipping points that could reshape our world with devastating consequences for people and nature. This requires immediate, unprecedented action from COP30 leaders and policymakers around the world,” he said.