ScienceDaily: Denver released the largest amount of greenhouse gases (GHG) and Barcelona the smallest amount in a new study documenting how differences in climate, population density and other factors affect GHG emissions in global cities. The study, which could identify ways in which cities can reduce GHG emissions, is scheduled for October 1 issue of ACS’ Environmental Science & Technology, a semi-monthly journal. Christopher Kennedy and colleagues note in the new study that some …