A Row Of Climate 'Dominoes' Is About To Fall, Threatening Human Existence, With No Way Back
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 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 collapse of major ice sheets on Greenland, West Antarctica and part of East Antarctica would commit the world to around 10 metres of irreversible sea-level rise,” he said.
"Even if these polar ice sheets are ‘tipped’, reducing emissions could slow this process, allowing more time for low-lying populations to move."
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," Steffen said.
“Tipping point risks are now much higher than earlier estimates... currently we are seeing much higher risk, and we are rapidly running out of time to respond.”
The warning comes just days after a United Nations report found greenhouse gas emissions surged to a record level last year and world temperatures could rise by more than twice the globally agreed warming limit if nothing is done.
The "Emissions Gap Report" is one of several studies released ahead of UN climate talks in Madrid next week aimed at spurring world leaders to limit climate change.
Under current national pledges to cut emissions, "temperatures can be expected to rise by 3.2 degrees this century, bringing wide-ranging and destructive climate impacts," said a summary of the report by the UN Environment Program (UNEP).
The report said the safest temperature threshold set in Paris -- of 1.5 degrees-- was still achievable, but would require emissions cuts of 7.6 percent a year between 2020-2030, the report said. Limiting the rise to two degrees it would mean annual cuts of 2.7 percent.
"We are talking about transformational change now -- incremental change simply will not make it. We simply need to transform societies in the next 10 years," said the report's lead author John Christensen.
"The longer you wait, the more difficult it becomes."