In my coverage of Earth system science (pp. 42-46 of my book) I featured a cutting-edge study of tipping points that has just been updated in the journal Nature. It can be read online here, or a PDF version downloaded from the same URL. The core message of this article is that global warming must be limited to 1.5 °C, and that this requires an emergency response.

The authors review the various tipping points reproduced in Figure 3.3 in my book, both individually and as a “global cascade” to conclude that “the intervention time left to prevent tipping could already have shrunk towards zero, whereas the reaction time to achieve net zero emissions is 30 years at best. Hence we might already have lost control of whether tipping happens. A saving grace is that the rate at which damage accumulates from tipping — and hence the risk posed — could still be under our control to some extent.”

While the Intergovernmental Panel on Climatic Change report Global Warming of 1.5℃ released on 6 October has received widespread publicity, other reports less diluted by political compromise deserve more attention and indicate much greater urgency. Foremost among these is the open-access journal article Trajectories of the Earth System in the Anthropocene by a world-class team of climate scientists, which shows that even if the carbon emission reductions called for in the Paris Agreement are met, there is a risk of Earth entering what the scientists call “Hothouse Earth” conditions. If this happens, the climate will in the long term stabilise at a global average of 4-5°C higher than pre-industrial temperatures with sea level 10-60 m higher than today. The crucial difference between the IPCC predictions and those of “Hothouse Earth” are that the former ignore feedback processes, despite their well-understood importance universally accepted among Earth system scientists. Further commentary is available from the Stockholm Resilience Centre.