Climate News: Scientists declare crossing of the world’s first climate ‘tipping point’ as coral reefs enter irreversible decline

The planet has crossed its first major climate ‘tipping point’, scientists warn, as record ocean heat drives the widespread, irreversible collapse of warm-water coral reefs – ecosystems that support nearly a billion people worldwide.

The finding comes from the 2025 Global Tipping Points Report, authored by 160 scientists from 87 institutions in 23 countries and released by the University of Exeter. The report concludes that Earth has entered a ‘new reality’, with the mass mortality of coral reefs marking the first climate-driven ecosystem tipping point.

Coral reefs … have endured extreme stress as marine heatwaves pushed ocean temperatures to record highs

“We are rapidly approaching multiple Earth system tipping points that could transform our world, with devastating consequences for people and nature”, said Professor Tim Lenton of the University of Exeter. “This demands immediate, unprecedented action from leaders at COP30 and policymakers worldwide.”

Coral reefs, which host a quarter of all marine life, have endured extreme stress as marine heatwaves pushed ocean temperatures to record highs. More than 84% of reefs have suffered severe bleaching in the past two years, the report said. Their collapse threatens food security, coastal protection, and livelihoods across the tropics.

The report also warns that other critical systems are nearing dangerous thresholds, including the Amazon rainforest, the Greenland and West Antarctic ice sheets, and the Atlantic Meridional Overturning Circulation (AMOC) – a major ocean current that stabilises global weather. Scientists now believe some of these systems could fail with just 1.5–2°C of warming above pre-industrial levels, far lower than previously thought.

Renewable energy surpassed coal for the first time this year, offering a sign of progress

The planet has already warmed by around 1.3–1.4°C since pre-industrial times and is on track for 3.1°C by 2100, according to an October 2024 UN projection.

Despite the bleak outlook, researchers urged world leaders to trigger ‘positive tipping points’: rapid transitions to clean energy, reforestation, and emissions cuts. Renewable energy surpassed coal for the first time this year, offering a sign of progress.

“Only with decisive action can we tip the balance from catastrophic to hopeful”, Lenton said. “Twenty years ago, it was thought that it would take four to five degrees of global warming for tipping points to become as likely as not; now we think that is the case in the one-to-two-degree range of global warming.”

The warning comes just weeks before COP30, to be held in Brazil at the edge of the Amazon – another ecosystem now on the brink.