Australia's failure to address climate change will cause a significant national security threat, according to a report by the Centre for Policy Development. 

The report, called The Longest Conflict: Australia's Climate Security Challenge, says Australia's Defence Force is underprepared for climatic events like extreme heat, rising sea levels and more frequent natural disasters. 

It warns of escalating regional tensions over food and growing numbers of internally displaced people and refugees. 

The former head of the ADF, retired Admiral Chris Barrie, launched the report and blamed politics for the failure to take the issue seriously. 

"Most of the people I work with in Defence actually get this; they understand about climate change, and they're very enthusiastic to get to grips with it," he said. 

"The problem we've got is at the top level of politics in this country it seems to be a toxic term. 

"That's bad news and they know it's rubbish so let's get real about it and start having a decent conversation." 

The report says there is a perception the ADF has an "institutional reluctance to address this critical security challenge comprehensively". 

A new Defence white paper is due later this year, but senior Defence officials told the Centre for Policy Development climate change is unlikely to be seriously addressed. 

"[It's] very unlikely that the language of climate change will be used in the [Defence white paper] given the current political situation," the report said. 

One ADF interviewee said that in Canberra, "climate change is a dirty word". 

Former UK Climate and Energy Security Envoy Rear Admiral Neil Morisetti says the ADF is falling behind its major allies like the US and UK. 

"We know enough to know that we've got to act," he said. 

"If you take for example the reports that came out last year from the inter-governmental panel on climate change, 95 per cent of the scientists are saying this is happening, and the pace and nature of things happening reflects the pace and nature of human activity," he said. 

Anthony Bergin, from the Australian Strategic Policy Institute, said the impacts of extreme heat cannot be ignored. 

"Think about the implications of health for our 80,000 full-time and part-time military soldiers, sailors and airmen with a significant increase in temperature," he said. 

"Just as elite sportsmen have to manage operating in a changing climate, so too do our armed forces." 

He says climate change could cause regional upheaval. 

"The impacts of sea level rise may involve the displacement of people resulting in implications for border security," he said. 

"Climate change may well have impacts on food production, a rise in food prices, resulting in political instability in a region." 

Mr Bergin also warned of ramifications to deploying troops, with changing weather threatening the reliability of traditional fuel supplies. 

"Both in Britain and the US they're increasingly looking at alternative fuels, not only to decrease their carbon footprint, but also to increase their sustainment in operations," he said. 

Watch Margot O'Neill's full report plus live interviews on Lateline tonight at 9:30pm (AEST) on ABC News 24 and 10:30pm on ABC TV.