The Federal Administrative Court ruled this week that German cities can legally ban diesel vehicles.
This US state already has ambitious plans to get 1.5 million zero-emission cars on its roads by 2025.
Oxford in the UK wants to become the world's first carbon emission-free city by 2035, with a plan to ban all petrol and diesel vehicles from the city centre over the next 20 years.
The country’s ambitious plans to stem climate change will be a challenge.
India is taking on its air pollution problem by announcing a daring plan to eliminate petrol and diesel powered cars from the roads by 2030.