Reuters: A small reference on page 776 of a mammoth U.N. scientific report to cuts in greenhouse gases far deeper than those on offer by rich nations has become a main roadblock towards a new U.N. climate treaty. For developing nations at two-week U.N. talks in Bonn ending on Friday, the outlined emissions cuts by developed nations of 25 to 40 percent below 1990 levels by 2020 have become vital for a deal due to be agreed in Copenhagen in December. Many developed nations, however, say …