Guardian: You've probably heard that US carbon emissions have been falling. According to President Obama and energy commentators the world over, fracked shale gas has displaced dirty coal, in much the same way that fossil fuels undercut whale oil a century earlier. Out with environmentally unfriendly old technologies and in with cleaner and more efficient new ones. Everyone wins including the climate, thanks to the fact that gas produces only around half as much CO2 as coal does for each unit of power or...