Agence France-Presse: Thousands of campaigners marched in London on Saturday to demand that the government take more action to prevent climate change. Organisers said 10,000 people took part in the colourful procession to the Houses of Parliament, which coincided with a meeting of 192 nations in Poznan, Poland, to draft a new international climate change treaty. Kate Tansley, of the march organisers Campaign against Climate Change, said the protest highlighted four issues, including a call for plans …