Australia

Scientists warn world is approaching climate tipping points

A scientist measures coral mortality following bleaching on the northern Great Barrier Reef. Source: AAP

A group of scientists, including Australian Will Steffen, have warned the globe is reaching several tipping points that could lead to massive releases of carbon.

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.

Antarctica is melting more than six times faster than it did in the 1980s.
Antarctica is melting more than six times faster than it did in the 1980s.
NASA/Jeremy Harbeck

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 commentary for scientific journal Nature, published on Thursday.

"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.

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14 November: Former emergency chief's climate change warning
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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.

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