The dominoes of uncontrollable massive releases of carbon dioxide are dangerously close to tipping and could push the planet into a state that threatens human civilisation.
A group of seven leading scientists warn that the globe is nearing nine major tipping points.
These include coral die-offs in the Great Barrier Reef, the extensive loss of Arctic sea ice and ice sheets in Greenland and Antarctica, the thawing of permafrost, and the destruction of boreal forests in high-altitude areas and the Amazon rainforest, they say in a , published on Thursday.
Antarctica is melting more than six times faster than it did in the 1980s. Source: NASA/Jeremy Harbeck
"As soon as one or two climate dominoes are knocked over, they push Earth towards others," says ANU climate expert Will Steffen, one of the authors.
"We fear that it may become impossible to stop the whole row of dominoes from tumbling over, forming a cascade that could threaten the existence of human civilisations."
He says each of these tipping points could trigger massive and uncontrollable releases of carbon into the atmosphere from where it had previously been stored on Earth.
That, in turn, would accelerate the heating and further destabilisation of other ice sheets.
The tipping points were identified two decades ago and it was initially thought they would only be reached if the Earth heated by five degrees.
But the two most recent Intergovernmental Panel on Climate Change special reports said they could, in fact, happen with warming of between one and two degrees.
The scientists warn the worst-case scenario is a "hothouse Earth" that would be far less hospitable to humans.
An emergency response of rapid action to reduce emissions is needed to stop this "tipping cascade", they say.
"All nations need to recognise the seriousness of the situation and go well beyond their Paris Agreement pledges to cut emissions," Prof Steffen said.
