“The Australian government is in utter and complete denial,” he said.
“Under its current leadership, Australia is fostering denial in an incredibly mendacious way.
“Until Australians throw out their current leaders they will continue this way … It’s time to wake up.”
Brown is the longest serving governor in the history of California, which has almost 40 million residents – more than any other US state. He served two terms beginning in 1975 before returning to office again in 2010.
Brown made climate change his signature issue, suing the Trump administration over its environmental policies and mandating 100 per cent carbon-free electricity in the state by 2045.
He is now executive chair of the Bulletin of the Atomic Scientists, which moved its Doomsday Clock forward to 100 seconds to midnight. This is the first time it has passed the two-minute mark since it was launched in 1947.
Rachel Bronson, chief executive of the Bulletin of the Atomic Scientists, said: “We are now expressing how close the world is to catastrophe in seconds, not hours or even minutes.
“We now face a true emergency – an absolutely unacceptable state of world affairs that has eliminated any margin for error or further delay.”
Sivan Kartha, a senior scientist at the Stockholm Environment Institute, said: “To test the limits of earth’s habitable temperature is madness. It’s a madness akin to the nuclear madness that is again threatening the world.”
He said extreme weather events over the past year were a portent of what was to come unless the world takes drastic action on climate change.
“Wildfires raged from the Arctic to Australia,” Kartha said.
“They now persist with an unprecedented intensity, extent and duration that makes them harder to contain … The very idea of a limited fire season is becoming a thing of the past.”
Former United Nations secretary-general Ban Ki-moon said: ‘From the US withdrawal from the Paris Agreement and the Iran nuclear deal, to deadlock at nuclear disarmament talks and paralysis at the UN security council, our mechanisms for collaboration are being undermined when we need them most.”
Speaking from the World Economic Forum’s annual meting in Davos, Switzerland, Finance Minister Mathias Cormann defended Australia’s record on climate change.
“We have a very ambitious climate change policy, we are absolutely committed to effective action on climate change,” Cormann told CNBC.
“We are a large continent with a small population, so considering the emissions reduction targets we’ve committed to on a per capita basis we will be more than halving emissions and indeed we will be reducing the emissions intensity in our economy by two-thirds.
“That is more ambitious than the UK, than Canada, than New Zealand, than many other countries around the world.”
Matthew Knott is North America correspondent for The Sydney Morning Herald and The Age.