Agence France-Presse: European leaders who once saw Barack Obama’s election as a new dawn in the battle against global warming are becoming concerned, three months ahead of a key UN climate summit in Copenhagen. One sign of this is the revival of the idea for a “carbon tax” to protect Europe’s industry and environment, amid fears that Europe’s commitments on tackling climate change will not be matched in the United States and elsewhere. “I confess that I am very worried by the prospects for …