Prince Charles has warned Scott Morrison an upcoming global climate conference will be "a last chance saloon" to take action, after being told the prime minister might not attend.
In an interview with the BBC, the future king was asked why it was so important for world leaders to go to COP26 in Glasgow, given Mr Morrison might skip the conference.
"Well, that's what I'm trying to say all the time, and the point being that this is a last chance saloon, literally," the Prince said.
"Because if we don't really take the decisions that are vital now, it's going to be almost impossible to catch up."
The UN climate conference will be held from 31 October to 12 November and will be attended by US President Joe Biden and about 100 world leaders, as well as Prince Charles and the Queen.
Mr Morrison is yet to announce a decision on whether he will fly to Glasgow to attend the talks.
But SBS News understands it is highly likely the Prime Minister will attend the upcoming Cop26 summit as well as a meeting of the G20 leaders.
In the interview, Prince Charles said he shares the concerns of Greta Thunberg and other environmental activists that world leaders "just talk" about climate change and were not doing enough to prevent its catastrophic impact.
The heir to the British throne, 72, who has spent most of his life speaking out on green issues, said he understood why campaigners took direct action when faced with the inactivity of politicians.
"They just talk," Prince Charles told BBC TV in the interview broadcast on Monday.
"And the problem is to get action on the ground."
His views echo remarks from Ms Thunberg and her fellow youth campaigners at a Youth4Climate event in Italy last month when she accused world leaders of "thirty years of blah, blah, blah".
Prince Charles said he understood young people's despair and why groups such as Extinction Rebellion took to the streets to carry out disruptive protests.
"All these young people feel nothing is ever happening, so of course they're going to get frustrated. But it isn't helpful, I don't think, to do it in a way that alienates people," he said.
"So I totally understand the frustration, the difficulty is how do you direct that frustration in a way that is more constructive rather than destructive. The point is that people should really notice how despairing so many young people are."
Prince Charles will be joined by his mother Queen Elizabeth and his eldest son Prince William for events at the COP26 summit.
He has been calling for governments to work with business and the private sector to help solve the climate crisis.
Without action "it will be a disaster", he said.
"It will be catastrophic. It is already beginning to be catastrophic."
Questioned about his own green credentials, given his passion for cars and the carbon impact of royal palaces, Prince Charles revealed he had converted his 51-year-old Aston Martin to run on surplus white wine and whey from making cheese, and had installed biomass boiler systems and solar panels at his homes.
He also said he did not eat meat or fish two days a week, and had no dairy products on Mondays.
Health Minister Greg Hunt said the Australian government would be "represented at a very high level as a nation" at the Glasgow summit.
"We will make very clear, real, deliverable commitments with a plan," he told reporters.
