As the world warms, the U.S. military will inevitably be called upon to conduct more disaster relief and humanitarian-aid missions. The U.S. military, of course, is not a polar-bear rescue operation. "The military has many important roles," says Sharon Burke, a former assistant secretary of defense. "But the main job is to fight wars. That means breaking things and killing people." But the military also prides itself on its practical-mindedness, both in times of war and of peace. Military leaders embraced desegregation long before the rest of the nation, in part because they wanted the best people they could find, no matter what color. "It's our job to deal with the world as it is, not as we wish it could be," says Robert Freeman, a meteorologist and member of the Navy's climate-change task force.