British Prime Minister has warned his country will face a catastrophe of floods, droughts and killer heat waves if world leaders fail to agree a deal on climate change. Gordon Brown said negotiators had 50 days to save the world from global warming and break the impasse. He told the Major Economies Forum in London, which brings together 17 of the world's biggest greenhouse gas-emitting countries that there is no plan B. Mr. Brown warned that negotiators are not reaching agreement quickly enough and said it is a profound moment for the world involving momentous choice. He said the costs of failing to tackle the issue would be greater than the impact of both world wars and the Great Depression combined. World leaders will meet in Copenhagen in December for talks on a new treaty.