Press Association: Environment chiefs from top industrial countries have called for an agreement on cutting greenhouse gas emissions in half by 2050, declaring that developed nations should take the lead in battling global warming. The statement by ministers from the Group of Eight (G8) nations, aimed at preparing for action on climate change at the G8 summit in Toyako, Japan in July, also acknowledged calls for midterm emissions reduction targets for 2020, though it did not specify any …