Reuters: Japan has yet to persuade the United States to agree to a global goal of cutting greenhouse gas emissions by 50 percent by 2050 at a G8 leaders’ summit, a Japanese government source said on Thursday. Summit host Prime Minister Yasuo Fukuda faces the prospect of a diplomatic failure at next month’s talks if Washington refuses to agree to a 2050 emissions target. A weak summit showing could erode Fukuda’s support rates, which have shown a slight bounce after dropping below 20 …