UCL Research Domains


UCL Scientist Professor Chris Rapley Comments on 'Hothouse' Earth

UCL Professor of Climate Science, Chris Rapley, is amongst scientists to comment on the future state of the Earth System following a recent report featured in the proceedings of the National Academy of Sciences of the United States of America. Report authors Steffen et al. warn of the potential of a 'Hothouse Earth', whereby self-reinforcing feedbacks could push the Earth System through a planetary threshold to a new state characterised by a combination of high global temperatures and rising sea levels unprecedented in the Holocene.This would be amplified by the weakening of naturally stabilising feedbacks within the Earth System due to the human forcing. A rapid, human driven trajectory of the Earth System away from the natural glacial-inter glacial limits would have devastating impacts on ecosystems, society and economies. 

Professor Rapley echoes concerns regarding the concurrent human influence driving the Earth System towards a 'Hothouse' state whilst "simultaneously weakening the 'Gaia' feedbacks that have helped maintain a stable climate state conducive to the growth of human civilisation and general prosperity of the modern world". Furthermore, Rapley highlights that a runaway warming to a new and uncontrollable hot state would pose an existential threat to humanity and the majority of existing species. 

Through their summary, Steffen et al. urge for collective human action to avoid reaching the 'Hothouse' threshold, calling on the world's societies to make international efforts to reduce human impacts on the Earth System and promote effective Earth System Stewardship. This would require changes in demographics, consumption, behaviour, attitudes, education, institutions and socially embedded technologies underpinned by mobilisation of institutional and social innovation at the global governance level, and a stronger emphasis on planetary issues in politics, trade, finance and technological development.

Whilst this provides an idealistic solution to the threat, Professor Rapley suggests that given the evidence of human history, this would seem a naïve hope. Highlighting that "at a time of the widespread rise of Right Wing Populism, with its associated rejection of the messages of those perceived as "cosmopolitan elites" and specific denial of climate change as an issue, the likelihood that the combination of factors necessary to allow humanity to navigate the planet to an acceptable "intermediate state" must surely be close to zero."

It seems that whilst the 'Hothouse Earth' conditions explored by Steffen et al. may be uncertain, they are certainly not implausible, and the main tasks facing civilisation are not only how best to deal with the threat of runaway warming, but whether humanity has the combination of necessary factors to co-ordinate a collective response.

If you are a UCL academic with an interest in climate change you can join the Environment Domain Climate Change Working Group, please contact Dr Becca Burns via environment@ucl.ac.uk