Independent: Leaders of the world’s richest nations have kept alive hope of a global agreement to combat climate change by agreeing to cut their carbon emissions by at least 50 per cent by 2050. Environmental groups said the agreement at the G8 summit in Japan did not go far enough, and the search for a deal moves to the talks about a “son of Kyoto” global agreement in Copenhagen next year. George Bush, who had previously stalled progress by agreeing only to “seriously …