Guardian: Later this month world leaders will gather in New York for a historic summit on climate change. This is an opportunity to inspire key decision-makers to act in the face of a growing climate crisis that threatens almost every aspect of our lives. Politicians all over the world cite a lack of public support as a reason not to take bold action against climate change. So on 21 September we will meet this moment with unprecedented public mobilisations in cities around the world, including thousands of...