Around 56 percent of the world's population currently live in cities, a figure that is expected to increase in coming decades. It follows that these urban areas account for a large amount of the world's greenhouse has emissions, and a new study designed to gauge the scale of this pollution has concluded that around half come from just 25 cities, with so-called megacities in China and Japan proving to be particularly potent emitters.

“Nowadays, more than 50 percent of the global population resides in cities," says co-author Dr Shaoqing Chen, of Sun Yat-sen University. "Cities are reported to be responsible for more than 70 percent of greenhouse gas emissions, and they share a big responsibility for the decarbonization of the global economy. Current inventory methods used by cities vary globally, making it hard to assess and compare the progress of emission mitigation over time and space."

+INFO: New Atlas