Michael R. Bloomberg, BloombergView: “We need leadership from the White House — and over the past four years, President Barack Obama has taken major steps to reduce our carbon consumption, including setting higher fuel-efficiency standards for cars and trucks. His administration also has adopted tighter controls on mercury emissions, which will help to close the dirtiest coal power plants (an effort I have supported through my philanthropy), which are estimated to kill 13,000 Americans a year.”