Newsweek: To President Barack Obama, climate change is a threat to national security. To Jeb Bush, a likely Republican presidential candidate, it's not clear how much humans are to blame for the Earth's fluctuating climate. In his ongoing effort to combat climate change, Obama on Wednesday warned the graduates of the United States Coast Guard Academy that denying or refusing to act on the divisive issue is negligence and a dereliction of duty. "It undermines the readiness of our forces," he told the cadets...