Canwest News Service: Scientists have turned up the heat on the Harper government and are calling for urgent action on climate change. “We must act responsibly. We must act now. We must act in concert with other industrialized nations,” leaders of organizations representing more than 3,000 scientists said in an open letter to parliamentarians Thursday. They note that the “eyes of the world will be on Canada” at the international climate talks in Copenhagen and “urge the government to negotiate an …