Thousands of activists have gathered in New York's Central Park to take part in an event calling on world leaders to "stop the clock" on climate change. They created a human hourglass outside the United Nations building. It contained a representation of the earth trapped inside which dissolved like sand. According to Barbara Stocking, Chief Executive of Oxfam in the UK who helped organize the event, the point was to highlight climate change to push leaders to send a strong message during their meetings that there will be a comprehensive agreement reached at Copenhagen in December. She said: "This is a global problem, where we need the governments of the world and the heads of state stand up and be global leaders and say that 'we're really going to be bold, and we are going to do this.' And we want to see signs of that this week."