In his commencement address to the United States Military Academy last week, President Obama called climate change a "creeping national security crisis." He means that there will be refugee flows, natural disasters, and conflicts over water and food. But really, in my narrow mind, nothing is a security crisis unless it involves violence or the threat of it. Does climate change pose that threat? Then-Defense Secretary Robert Gates made that point over six years ago.
Bruce Johnsen at George Mason once offered this example. "I'm a big guy [he is]. But if I am threatened by violence on a dark street by someone smaller than me who wants my wallet, I will give it to him even if he is unarmed. Even though I may have an absolute advantage in violence, that person is likely to have a comparative advantage in violence." I am paraphrasing, but you get the point. Also, surely Professor Johnsen is not the only person to have made this point, but he is the only big guy I know to have made this point.
The point is that people have different opportunity costs of violence. A poor mugger on the streets may have a less than 50-50 chance of winning a fight against Bruce Johnsen (that was a few years ago), but because of his extraordinarily low opportunity costs of injury, it is a chance he might take. Professor Johnsen, on the other hand, might have to cancel classes, miss conferences, and *gasp* -- even miss faculty meetings! His costs of injury would be very high. Wealth inequalities are dangerous precisely because they create vast disparities in the opportunity costs of violence.
So goes it with climate change. As the rich get richer and the poor get relatively poorer (indulge me for a moment, as Professor Johnsen noted that these claims are inferential, and may underestimate the adaptive capacity of poor nations) in a climate-changed world, the poor are likely to respond by fighting. Poorer nations are likely to respond with violence, because, after all, when your country is threatened by flooding and tropical storms, what really do you have to lose?