“When you look at the lifestyle of people living in cities, they can often be better in terms of carbon emissions than people in the country,” said David Dodman, a geographer and climate change scientist who headed the IIED research effort. “In certain cities, particularly in high-income countries but also in rapidly industrializing countries, the emissions from city dwellers were less than the average emissions form the country as a whole.”

The IIED report, which was published in 2009, spawned 20 or 30 follow-up studies, all of which told a similarly positive story about urbanization. “[All of the] studies have shown that urbanization can have benefits in terms of lowering greenhouse gas emissions,” Dodman told Life’s Little Mysteries.