SHENZHEN — China's southern boomtown Shenzhen has launched a smartphone application that displays information on carbon emissions to encourage residents to cut their carbon footprints. In the application, residents can see how much carbon dioxide is emitted from the daily electricity their households consume. The data can be compared with the city's average to learn how much carbon emission is saved. It also shows the accumulated carbon emissions they have helped avoid, as well as a ranking among users. Virtual badges are offered on the application to encourage carbon emission reduction. It is expected that, in 2023, residents can authorize…