HUMANITY faces doomsday within decades as climate change reaches a tipping point that triggers runaway global warming, scientists warn.
A rise of 2C will set off an uncontrollable chain of events, say researchers at Cambridge and universities in Stockholm, Exeter and Arizona. These end with a 5C increase that could raise sea levels by up to 197ft and threaten ‘the habitability of the planet for humans’.
Dr Phil Williamson, from the University of East Anglia, said: ‘In the context of the summer of 2018, this is definitely not a case of crying wolf or raising a false alarm. The wolves are now in sight.’ Governments worldwide have committed to keeping temperature rises to no more than 2C above pre-industrial levels, but scientists now warn this will not be enough.
The planet is now 1C hotter — averaging 14.8C — and warming at 0.17 degrees per decade, potentially reaching the deadly tipping point in 50 years.
Ten events ending in ‘hothouse Earth’ are referred to in the paper published in Proceedings of the National Academy of Sciences.
They include thawing permafrost, methane released from the ocean floor, weakening land and ocean carbon sinks, increased CO2 from ocean bacteria, dying Amazon rainforests and coniferous trees, reduced northern hemisphere snow, loss of Arctic summer sea ice, reduced Antarctic sea ice and melting polar ice sheets.
Lead author Prof Johan Rockström, of the University of Stockholm, said: ‘Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over.’
Carbon dioxide is at its highest for 800,000 years, a US study released last year found. The researchers warn deeper cuts to emissions than those in the Paris climate change agreement are needed along with technology and methods to remove existing CO2.