With the new Trump administration questioning the existence of climate change, The National Science March - which began as a suggestion on Facebook - has turned into a fully-fledged organisation. On April 22 the group wants to convince the country to listen to its scientists instead of its politicians. But can a march really make a difference? Al Jazeera’s Jacob Ward reports from San Francisco. - 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/