Climate change is a security issue.

Climate change will lead to desertification, soil erosion, loss of arable land, and droughts. Resources such as fresh water and land will be in shorter supply. Thus nations may wage war to forcibly gain control of these essential resources from other nations.

Experts believe that the effects of climate change are not only negative in themselves, but may also exacerbate existing areas of political and social tension.

As an example, John Ashton, the UK Foreign Secretary's Special Representative for Climate Change, is of the opinion that recent climate change was a factor in the Darfur conflict's "complex roots". Rainfall in northern Darfur had declined by almost 40 per cent over the last century, creating increasing competition for water between previously co-existing peoples.

In a similar vein, Sir Crispin Tickell, the former UK Permanent Representative to the UN, highlights the environmental factors behind societal collapse. The genocidal inter-ethnic Rwandan conflict in 1994, he argues, stemmed partly from a population increase set against a background of land degradation and drought.

Food shortage, death, disease and loss of home will all lead to violence and radicalisation.

Migration due to climate change may also create tension and lead to violence

It has been shown that non-renewables (such as oil) rather than natural resources often lie at the centre of conflicts. 
 
Scarcity of resources doesn't inevitably lead to conflict.