Guardian: International negotiators lost one of the key elements to a successful deal on global warming today after Democratic leaders in the US Congress ruled out passing a climate change law before 2010. In the latest obstacle on the road to the UN summit in Copenhagen next month, Senate leaders ordered a five-week pause to review the costs of the legislation. The delay, which would push a Senate vote on a climate change bill into next year, frustrates a last-minute push by the German …