A new report warns that humanity has crossed the first critical Earth system tipping point with the widespread death of warm-water coral reefs. Released on October 13 by the University of Exeter and international collaborators, the study highlights risks of further irreversible changes as global temperatures exceed 1.5°C. Urgent action is needed to trigger positive tipping points like renewable energy adoption to avert cascading crises.
The second Global Tipping Points Report, produced by 160 scientists across 87 institutions in 23 countries, concludes that warm-water coral reefs—vital to nearly a billion people and a quarter of marine species—have passed their threshold of stability. Mass coral die-off is underway, and unless global warming is reversed, large reef systems will disappear, with only isolated refuges possibly enduring under urgent protection.
Researchers emphasize that this marks the beginning of multiple interconnected tipping points. With current warming at about 1.4°C, reefs are passing their thermal tipping point (central estimate 1.2°C, range 1-1.5°C). Even stabilizing at 1.5°C, reefs are virtually certain (over 99% probability) to tip, leading to loss unless temperatures return toward 1°C or below. Other risks include melting polar ice sheets, disruption of major ocean currents like the Atlantic Meridional Overturning Circulation (AMOC) below 2°C, and Amazon rainforest dieback, now estimated at a lower threshold of 1.5°C due to climate change and deforestation.
The report, timed ahead of the COP30 summit in Brazil, urges limiting temperature overshoot. Professor Tim Lenton of the University of Exeter's Global Systems Institute stated: "We are rapidly approaching multiple Earth system tipping points that could transform our world, with devastating consequences for people and nature. This demands immediate, unprecedented action from leaders at COP30 and policymakers worldwide."
Dr. Mike Barrett, chief scientific advisor at WWF-UK and a co-author, added: "The findings of this report are incredibly alarming. That warm-water coral reefs are passing their thermal tipping point is a tragedy for nature and the people that rely on them for food and income."
Positive developments include crossed tipping points in solar PV, wind power, electric vehicles, battery storage, and heat pumps. The authors advocate accelerating these through policy to cut emissions and scale carbon removal. They are collaborating with Brazil's COP30 Presidency on an Action Agenda to prioritize tipping points at the summit.
Dr. Manjana Milkoreit from the University of Oslo noted: "Current policy thinking doesn't usually take tipping points into account. Tipping points present distinct governance challenges... requiring both governance innovations and reforms of existing institutions."
Ambassador André Corrêa do Lago, COP30 President Designate, welcomed the report as evidence that humanity can evolve toward a safe future through collective efforts.