Agence France-Presse: A global carbon price of at least $32 (24 euros) per tonne is needed by 2015 to apply an effective brake on global warming -- almost five times today's European market rate, a study said Monday. Co-authored by British economist Nicholas Stern, an authority on the costs of climate change, the report reviewed a widely-used model for assessing risk and found it led to a "gross underassessment" of danger. This beefs up the case for strong cuts in greenhouse gas emissions, helped by a carbon price "in...