It's official: we no longer live on a planet with temperatures that can sustain warm-water coral reefs.

This is the first of many fragile Earth systems set to topple as human activities continue to stoke our planet's fever, the 2025 Global Tipping Points Report warns.

Mass reef dieback occurs at an estimated 1.2 °C warming above preindustrial averages, a point the report – involving 160 scientists across 23 countries – confirms we're well beyond.

"I recognize that engaging with tipping points and talking about these risks is emotionally challenging," University of Oslo sociologist Manjana Milkoreit, who contributed to the report, told ScienceAlert. "Maybe the most important but also most difficult thing anybody can do is not to turn away and ignore this problem."

Earth's most vibrant underwater gardens, from the Great Barrier Reef in Australia to Florida's Sombrero Reef, are being annihilated by human-caused global warming. Four global coral bleaching events have now been recorded, with two of these occurring in the last decade. In this time, the Great Barrier Reef alone bleached in 2016, 2017, 2020, 2022, 2024, and 2025.

"The world has just spent much of the last two years at 1.5 °C warming, and the resulting marine heatwaves have caused unprecedented bleaching of 80 percent of the world's reefs," University of Exeter earth system scientist Tim Lenton told ScienceAlert.

These repeat mass bleaching events are now occurring too close together for reefs to recover, triggering the mass death of corals we're now witnessing and threatening the myriad of creatures that call these once-thriving ecosystems home.

"Half-a-billion people depend on these reefs for their livelihoods, including fishing and coastal protection, and the ecosystem services the reefs provide are valued at over US$2 trillion per year," explained Lenton.

"Reefs can bounce back, but only if we manage to cool things back down again."