In this instalment of FRANCE 24's special series on the Paris Climate Conference, we look at the role of urban crusaders.
Cities produce an estimated three quarters of greenhouse gas emissions. The result is not always pretty.
New Delhi, a city of 8 million cars, is rated the most polluted in the world. Beijing is often dubbed the home of China's "airpocalypse". And even in Paris, the Eiffel Tower is regularly masked by a haze of smog.
We explore how cities can help turn the climate change battle around.
To discuss this issue, we speak to Rajendra Shende, former director of the United Nations Environment Programme and now chairman of Terre Policy Centre and Celia Blauel, Paris deputy mayor in charge of the environment and sustainable development.