Former prime minister Malcolm Turnbull was confronted by "the reality of climate change" as he flew back into a smokey Sydney on Friday morning.
Mr Turnbull posted a photo on Instagram of the view out of his plane window as he flew over the CBD, with the Sydney Harbour Bridge barely visible in the orange glow of the smoke-filled sky.
"I have flown back into Sydney many times but never to a sight like this. The reality of climate change - hotter and drier means more fires," he wrote.
"We have to accelerate the move to zero-emission energy. It will mean a safer planet for our children and more affordable energy."
Bushfire smoke from dozens of blazes burning across the state has lingered over the city for days, with some parts of Sydney recording hazardous air quality levels.
Mr Turnbull has become increasingly vocal about climate change since leaving politics, telling Liberal Party members earlier this week to be "loud Australians" on climate change.
The Daily Telegraph reported Mr Turnbull told the private function of moderate factional allies that the government's current climate policies were incoherent.
Prime Minister Scott Morrison, who took over from Mr Turnbull in August last year, has dodged questions about the link between climate change and the unprecedented bushfires that have gripped New South Wales and Queensland since early November.
As he met with people who had lost their homes in the fire, he said it was not the time to discuss the causes of the fire.
His refusal to respond frustrated some bushfire victims, scientists and former emergency services chiefs, who blamed government inaction on climate change for increasing the threat of bushfires.
When pressed on the issue in an interview on ABC radio later in November, Mr Morrison said there was no "credible scientific evidence" that cutting emissions would reduce the severity of fires.
