Reuters: The United Nations’ top climate change official on Thursday called on Tokyo to push for ambitious midterm emissions targets at the G8 summit to be held in northern Japan in July. Yvo de Boer, in Tokyo for an official level climate change conference, told reporters that Japan faces the task of reaching a consensus among industrialized countries on 2020 targets for reductions in greenhouse gas emissions. "As chair of the G8, Japan could lead the discussion by moving forward …