Crowds in numerous cities marched to pressure world leaders meeting in Paris on Monday into strengthening environmental policyHundreds of thousands of people around the world, from Sydney to New York, marched on Sunday to call on world leaders meeting in Paris to agree a strong climate change deal.In Paris, pairs of shoes given by Pope Francis and Ban Ki-moon were among a collection set out in the Place de la République to represent those who were unable to march due to a ban by the French authorities in the aftermath of 13 November terror attacks.