The federal government has been urged to come up with a strategy to deal with social tension, conflict and people fleeing their homes as the climate changes.
A group of former defence and security officials, including former defence force chief Admiral Chris Barrie, wants the government to develop a National Climate Security Strategy.
"Climate change now poses the greatest threat to our security and the government should be engaging the electorate to build understanding of climate risks and how to respond," Admiral Barrie said.
"Instead, the government has a strategy of non-engagement when it comes to the most significant threat to our future. That is a fatal mistake."
Admiral Barrie said the world was facing severe climate events and increasing food and water insecurity.
"The government's lack of focus increases the risks of economic and supply chain disruption, social tensions, conflict and people displacement in our region becoming the norm," he said.
In parliament on Wednesday, independent MP Kate Chaney asked Defence Minister Richard Marles how the government planned to respond.
Mr Marles said climate change was a critically important issue for defence planning and strategy.
"I do accept that the pressures of climate change will give rise to a more complex and volatile strategic landscape," he said.
"So we will need to be very mindful of the way in which we posture ourselves in respect of that."
He noted it had been an issue for the defence strategic review released in April.
The Australian Security Leaders Climate Group's call for a strategy followed a successful push for a national climate risk assessment.
But the group is concerned the government has not made public a declassified version of the climate-security risk assessment completed by the Office of National Intelligence in 2022.
Retired Air Vice-Marshal John Blackburn, a former RAAF deputy chief, said the release of the assessment would go a long way to informing the public and parliamentarians about the "greatest threat to our nation and people".
"How can we expect our decision-makers to act in the nation's best interest when the government is deliberately keeping us all in the dark?" he said.
The group argues the national strategy should involve setting up an Office of Climate Threat Intelligence within the Office of National Intelligence, with an annual briefing to parliament.
As well, the climate science, risk analysis and policy-making capacities of the public service, CSIRO and the Bureau of Meteorology needed to be rebuilt.