Agence France-Presse: US President Barack Obama hailed an “historic consensus” on battling climate change Thursday, saying rich nations had a duty to lead the fight as they won backing from emerging powers. At expanded sessions at the G8 club of developed nations’ annual summit in Italy, an agreement was also reached that countries should resist calls for protectionism to cushion the impact of the economic crisis. Brazil, China, Egypt, India, Mexico and South Africa all joined the G8 on its second …