China and the United States are the world’s two biggest CO2 emitters, but what approach are these countries’ governments taking in the fight against climate change? In Shenzhen, one of China's most populous cities, new regulations to tackle air pollution are helping unleash a revolution in clean energy and transport. Meanwhile, the tone has changed in Washington DC with the Trump administration rolling back much of the environmental policies that had been made over the past decade. - Subscribe to our channel: http://aje.io/AJSubscribe - Follow us on Twitter: https://twitter.com/AJEnglish - Find us on Facebook: https://www.facebook.com/aljazeera - Check our website: http://www.aljazeera.com/