The changing climate will increase security threats to Australia, including the possible collapse of fragile states in the region and resource wars, a new report has warned.
The report, by the leading defence think-tank the Australian Strategic Policy Institute, says the speed of change means the nation's military planners can no longer brush off the likely impacts as they did in the 2009 white paper that saw no crisis emerging for at least two decades.
"That's no longer the case," Heavy weather: climate and the Australian Defence Force says.
"The downstream implications of climate change are forcing Defence to become involved in mitigation and response tasks right now."
The report says the Defence Force is poorly equipped to deal with the range of emerging threats - especially the potential need to deal with two major crises at once.
During the 2009 Victoria bushfires, Queensland floods and Cyclone Yasi the military deployed massive assets, including ships, aircraft, trucks and heavy-lift vehicles: 1500 troops were involved in the Queensland flood alone.
"No longer is the Christmas break considered a stand-down period of rest and relaxation," the report says. "It's become part of the ADF operational fabric.
"Certain ADF force elements are ready to be deployed at short notice over Australian summers in the event of floods, fires or cyclones ...
"What will happen when domestic infrastructure is damaged by an extreme weather event at the same time as another such disaster overseas requires a response?
"The ADF should start planning for responding to scenarios such as a devastating bushfire at home at the same time that a storm surge hits the Pacific."
The broader implications will require strategic re-thinking.
It says changes in climate patterns and their impact on the physical environment, including crop yields and food security, will have impacts on countries in Australia's area of strategic interest.
The report says the Asia-Pacific region will be affected by rising land surface temperatures, extreme events such as more powerful cyclones, more frequent floods, rising sea levels, heatwaves, and shifting disease patterns.
Australia and New Zealand will suffer increasing water problems, declining farm and forest productivity and, by 2050, greater vulnerability to rising sea levels and longer, more frequent droughts.
Asia will experience more frequent and longer heatwaves, declining access to fresh water, worse flooding - especially in the heavily populated "megadeltas" - and increasing pressure on natural resources from rapid urbanisation, industrialisation and economic development.
The small Pacific island states will become even more vulnerable to inundation, storm surge and erosion, the decline of natural resources, and rising threats to vital infrastructure, settlements and facilities that underpin local communities, including tourism.
The report says that the more severe effects of climate change, including increases in the frequency and severity of extreme weather and competition over natural resources, could contribute to instability, especially in fragile states.
"Climate change will exacerbate existing hardships and stresses in our neighbourhood, possibly risking the reaching of critical tipping points," it says.
Regional impacts that need to be considered by defence planners include the mass displacement of people.
"Failure to anticipate these changes and understand their cascading security implications could increase the threat of states failing."