The world’s 20 biggest-polluting countries will meet in Japan on Friday for a three-day climate conference designed as a run-up to the July G8 meeting where current G8 leader Japan wants to put climate at the top of the agenda. Japan has expressed support for cutting G8-country emissions by 50 percent from 1990 levels by 2050 — an ambitious-sounding, but relatively safe goal since the United States opposed an identical goal at last year’s G8 meeting and is likely to continue its opposition to setting any specific reduction goals. No one has especially high hopes for the upcoming climate meeting, but Yvo de Boer of the United Nations climate program said, “If the G20 meeting could agree on the 2020 emission reductions range for the group of industrialized countries as a whole, that would really help the process move forward.” Meanwhile, the U.S. will undoubtedly try to push the process backward.