America's Environmental Protection Agency has announced that greenhouse gases are a danger to human health. The ruling will allow it to regulate emissions without the approval of the US Congress - a move designed to show President Obama is taking climate change seriously. The president and more than 100 other world leaders, including Gordon Brown, are set to attend a summit at the end of the talks in Copenhagen, which take place until December 18. The meeting is being described as the "best, last chance" to save the planet. The Obama administration wants to show that the US, which has...