Climate disaster ‘just decades away’

EARTH may be decades away from a climatic tipping point which triggers ‘runaway global warming’ and threatens the future of humanity, scientists have warned.

The threshold will be reached when average global temperatures are only around 2C higher than they were in pre-industrial times, according to researchers. They are already 1C higher – and rising.

Feedback mechanisms acting ‘like dominoes’ will lead to a ‘Hothouse Earth’ period of uncontrollable climate change, the study predicts.

Temperatures will eventually stabilise at 4C-5C above pre-industrial levels, the researchers wrote in the journal Proceedings of the National Academy of Sciences.

If this happens, swathes of the planet around the equator will become uninhabitable and sea levels will rise by up to 60 metres (197ft).

The research highlighted ten feedback processes – including shrinking ice sheets and widespread droughts – that are predicted to kick in at around 2C of global warming. These ‘tipping elements’ could turn natural carbon storage systems or ‘sinks’ – such as plants – into powerful greenhouse gas emitters.

Co-author Johan Rockstrom, of the University of Stockholm, said: ‘These tipping elements can potentially act like a row of dominoes. Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row tumbling over.’

Avoiding a Hothouse Earth would require ‘deep cuts’ in greenhouse gas emissions and efforts to remove carbon dioxide from the atmosphere, the study said.

Chris Rapley, a professor of climate science at University College London said Hothouse Earth would represent ‘an existential threat to humanity’.