Earth ‘decades away’ from tipping point which triggers runaway climate change apocalypse

Metro.co.UK:Earth may only be decades away from a climatic tipping point that 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, new research suggests. They are already 1C higher and rising. Feedback mechanisms acting ‘like a row of dominoes’ will then spin the world into a ‘Hothouse Earth’ state of uncontrollable climate change.
Long term, the Hothouse Earth climate will stabilise at a global average of 4C-5C above pre-industrial levels, the study shows. If that happened, swathes of the planet around the equator will become uninhabitable, with sea levels up to 60 metres (197ft) higher than they are today, threatening coastal cities. A Hothouse Earth would pose ‘severe risks for health, economies, political stability, and ultimately, the habitability of the planet for humans’, the international scientists wrote in the journal Proceedings of the National Academy of Sciences. The research highlighted 10 feedback processes that were predicted to kick in at around 2C of global warming.The tipping point dangers were identified as thawing permafrost, the release of methane trapped on the ocean floor, weakening land and ocean carbon sinks, increased carbon dioxide production by ocean bacteria, Amazon rainforest die-back, coniferous forest die-back, reduced northern hemisphere snow cover, loss of Arctic summer sea ice, reduced Antarctic sea ice and melting polar ice sheets.