Reuters: Japan should set strong 2020 targets for greenhouse gas curbs since Tokyo will be judged against a past promise of a six percent cut, the head of the U.N. Climate Change Secretariat said on Tuesday. Japanese media suggest that Prime Minister Taro Aso will announce on Wednesday a seven percent cut by 2020 from 1990 levels when he chooses from six options ranging from a four percent rise to a 25 percent cut. “I am looking forward very keenly to the number that Japan will come …