Agence France Presse: Former British prime minister Tony Blair called on leaders from the Group of Eight powerful nations Friday to back a target to halve global greenhouse gas emissions by 2050 when they meet next month. Blair said the world must aim for “realistic and practical” solutions to bring on board major polluters, such as the United States and China, as he launched a report by the non-profit Climate Group ahead of the July 7-9 G8 summit in Japan. He urged the G8 industrialised …