C40 is a network of more than 80 of the world’s largest cities, committed to collaborating to address climate change through urban action. It aims to reduce greenhouse gas emissions and climate risks while increasing the wealth and wellbeing of urban residents. In the ten years of the network's existence, C40 cities have taken 10,000 climate actions, and they aim to reduce emissions by 3 gigatons of CO₂e by 2020.