BBC: he impact of rising temperatures on the world's food supplies is a key issue for climate experts meeting in Japan. But food security is not just about developing countries. As environment correspondent Matt McGrath reports, a changing climate is one of a number of issues pushing Japan towards a food crisis. In the historic Ueno Park in the middle of Tokyo, seemingly normal people are earnestly staring at trees. They are waiting for the first signs of cherry blossom, a spring event of special importance...