International climate scientists have warned in a new report that tropical coral reefs have already crossed their tipping point due to rising ocean temperatures. The Global Tipping Points Report 2025 highlights risks of cascading failures in other climate systems if global warming exceeds 1.5°C. The findings come ahead of the 30th World Climate Conference in Brazil.
The Global Tipping Points Report 2025, coordinated by Tim Lenton, Professor at the University of Exeter's Global Systems Institute, was released by more than 100 scientists from over 20 countries. It identifies roughly two dozen parts of the global climate system at risk of tipping points, where self-reinforcing changes become irreversible.
Tropical coral reefs are the first to have surpassed their threshold, estimated at about 1.2°C of warming. With current global warming at roughly 1.4°C above pre-industrial levels, reefs are suffering record mortality from repeated bleaching events. Even if temperatures stabilize at 1.5°C, most reefs would continue to collapse and would only recover if warming falls to 1°C or lower. Nico Wunderling, Professor of Computational Earth System Sciences at Goethe University Frankfurt and a lead author, stated: "The devastating consequences that arise when climate tipping points are crossed pose a massive threat to our societies. There is even a risk of the tipping of one climate system potentially triggering or accelerating the tipping of others. This risk increases significantly once the 1.5°C threshold is exceeded."
Other systems near tipping points include the Amazon rainforest, which could transform into savanna between 1.5-2°C of warming, accelerating global climate change; Greenland and West Antarctica ice sheets, potentially causing several meters of sea level rise; and the Atlantic Meridional Overturning Circulation (AMOC), including the Gulf Stream, which could fail at less than 2°C, leading to colder European winters, disrupted monsoons, and reduced agricultural productivity.
The report, first published in 2023, projects that 1.5°C warming will be reached within the next few years, potentially triggering multiple tipping points. It also notes positive tipping points, such as renewables now cheaper than fossil fuels in most areas and electric vehicles rapidly replacing gasoline models, which could accelerate sustainable transitions through policy support and social changes.
This update precedes the 30th World Climate Conference, starting November 10, 2025, in Belém, Brazil.