Extreme weather and rising sea levels caused by climate change will significantly increase the need for an effective defence force. It's why the military are taking notice of the scientists.

When Australian professors Colin Butler, Tony McMichael and Will Steffen stood up to talk climate change at a series of briefings in Canberra earlier this year there was something very different about the audience.

This wasn't a forum organised by an environment group where the seats are taken up by the usual cohort of the climate concerned.

Instead, this audience was full of hardheaded military types and members of the defence community - people worried more about conflict and geopolitics than wind turbines and carbon footprints. This invitation to speak on climate change had come from Australia's Department of Defence.

"They wanted to get a handle on the idea of tipping elements in the climate system that could cause rapid change that would be very difficult for human societies to deal with," says Professor Steffen, an Australian Climate Commissioner and executive director of the Climate Change Institute at the Australian National University.

Butler, Australian Research Council Future Fellow at the University of Canberra, displayed maps of places where climate change might act as a "threat multiplier" - food and water shortages in eastern parts of Asia and forced migration across Africa.

"The maintenance of peace and preventing war depends on more than just military personnel and hardware," says Professor Butler. "It also depends on what I call the 'determinants of peace' - that is, having enough basic resources of food, shelter and energy."

It's a far cry from 2009, when a Defence White Paper concluded that climate change would not be a serious consideration for the Defence Forces until at least 2030.

Australia's current National Security Strategy lists climate change as a broad global challenge "with national security implications" alongside the more obvious threats of corruption and the resurgence of violent political groups.

Last month in the journal Science, researchers reported the results of an analysis of "45 different conflict data sets" and found "strong causal evidence linking climatic events to human conflict".

When rainfall and temperatures started to shift, the study found a systematic increase in "the risk of many types of conflict".

For the complete article, please see ABC Environment.