The Australian Security Leaders Climate Group is urging the federal government to recognise the scale of the security risks at a time of rapid warming.
Former Defence chief Chris Barrie said Australia needed to reorder its foreign policy priorities, with traditional geopolitical risks set to be displaced by climate change.
"Australia has put all its eggs in the AUKUS basket, risking entanglement in a war with China, while the far greater threat to Australians' security is being ignored," he said.
The year 2024 was the first that exceeded pre-industrial temperatures by more than 1.5C, the ceiling set by the Paris agreement.
Global climate goals have not been breached, as average temperatures must have stayed above that level for 20 years, but the World Meteorological Organization estimates there's a 70 per cent chance average temperatures over the next five years will exceed 1.5C.
If average global temperatures exceed 3C, which is possible by the end of the century under existing policies, large parts of the tropics will be "near-unlivable" due to extreme heat.
"Three degrees will very likely mean widespread social conflict, large-scale people displacement, war, failed states and social collapse," the report said.
Recent research from Australian universities and Antarctic agencies confirmed the West Antarctic Ice Sheet was at "severe" risk of collapse, an event that would raise sea levels by three metres, damaging coastal communities in Australia and around the world.
The former national security leaders want foreign policy to reflect the threat posed by climate change, recommending the pursuit of climate-conditioned trade and investment linked to promises to phase out fossil fuel subsidies and similar commitments.
Reforming laws to prepare for climate migration and boosting finance for climate-vulnerable regions were also suggested by the security leaders.
"Security is not just about submarines and fighter jets — it's about food, water, homes, and health," said Cheryl Durrant, former director of preparedness and mobilisation at the Department of Defence.
"Without climate security, there is no national security."
The federal government is presently preparing its contribution to world temperature goals, a requirement every five years under the global pact and due before the next climate talks in Brazil.
It's also preparing a national climate risk assessment, a document that's now overdue.
The group of security leaders have been among the voices calling for its release, along with several federal crossbenchers, environmental organisations and climate-exposed industry groups.
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