] As the planet's carrying capacity shrinks, an ancient ] pattern reemerges: the eruption of desperate, all-out ] wars over food, water, and energy supplies. As Harvard ] archeologist Steven LeBlanc has noted, wars over ] resources were the norm until about three centuries ago. ] When such conflicts broke out, 25% of a population's ] adult males usually died. As abrupt climate change hits ] home, warfare may again come to define human life. Fortune.com: Grim Pentagon Climate Change scenario |