2. United States emissions had been declining because of increased burning of natural gas in power generation, which emits less carbon dioxide for each unit of energy than does coal. But the nation reported an increase in 2013 as coal regained some market share. If that trend continues, it could prove to be a challenge for the Obama administration as it seeks to institute tighter policies on greenhouse gases.
3. There are few chief executive decisions that drew more attention this year than Yahoo(YHOO, Fortune 500) CEO Marissa Mayer's work-from-home ban. The policy was initially seen as highly controversial and had a lot of people upset because of its perceived lack of flexibility.