Emissions have peaked in 27 of the C40 group of major cities, including London, New York, and Paris

So mayors announce at the Global Climate Action Summit in San Francisco. Emissions continue to fall. 66 cities expect to peak by 2020.

Wired: “That’s a big deal in the fight against climate change.” More than half the world’s population lives in cities – a proportion expected to grow.

Method: C40 compares a given city’s numbers year over year. To count as a peak, that high point in emissions must be at least 5 years ago, which avoids a false peak.

Image: screenshot from C40 website