The world is closer than thought to a “point of no return” after which runaway global heating cannot be stopped, scientists have said.
Continued global heating could trigger climate tipping points, leading to a cascade of further tipping points and feedback loops, they said. This would lock the world into a new and hellish “hothouse Earth” climate far worse than the 2-3C temperature rise the world is on track to reach. The climate would also be very different to the benign conditions of the past 11,000 years, during which the whole of human civilisation developed.
The public and politicians were largely unaware of the risk of passing the point of no return, the researchers said. The group said they were issuing their warning because while rapid and immediate cuts to fossil fuel burning were challenging, reversing course was likely to be impossible once on the path to a hothouse Earth, even if emissions were eventually slashed.
The assessment, which was published in the journal One Earth, synthesised recent scientific findings on climate feedback loops and 16 tipping elements. The tipping elements include the Greenland and Antarctic ice sheets, mountain glaciers, polar sea ice, sub-Arctic forests and permafrost, the Amazon rainforest and the Atlantic meridional overturning circulation (Amoc), a system of ocean currents that strongly influences the global climate.