A small mention in a large UN scientific report about the necessity for deeper cuts in greenhouse gases by rich nations has become a major issue hindering the progress of a new UN climate treaty. Developing nations at a two-week UN conference in Bonn are insisting on emissions cuts of 25 to 40 percent below 1990 levels by 2020 as crucial for reaching a deal at the Copenhagen summit in December. However, many developed nations argue that such reductions would harm their economies. Yvo de Boer, head of the UN Climate Change Secretariat, stated that the 25 to 40 percent target has become a key benchmark for measuring the success of the Copenhagen summit. The range of 25-40 was not included in the "summary for policymakers" of the IPCC report, which was based on a few studies and the work of 2,500 experts. Shyam Saran, special climate envoy to Indian Prime Minister Manmohan Singh, noted that little progress has been made on setting targets at the Bonn talks. Developing nations like China and India argue that wealthy countries should aim for emissions cuts of at least 40 percent from burning fossil fuels. Evidence of global warming, such as melting Arctic ice, has worsened since 2007. Small island states, concerned about rising sea levels, believe that rich nations should cut emissions by at least 45 percent below 1990 levels. Saran stated that achieving a forty percent reduction by 2020 is a reasonable goal if the problem is as significant as believed. De Boer mentioned that this level is not a confirmed target, but rather a potential scenario to mitigate the effects of global warming. Many developed countries, including the United States, believe this goal is unattainable. President Obama aims to reduce U.S. emissions to 1990 levels by 2020 and by 80 percent by 2050. Japan recently set a 2020 target of 8 percent below 1990 levels. Bill Hare of the Potsdam Institute for Climate Impact Research believes achieving a 25 percent reduction is still possible but will be challenging. He stated that recent scientific discoveries had supported the range of 25-40 percent. The exclusion of this range from the summary was due more to technical issues rather than doubts about its accuracy. The 25 to 40 percent figure gained significant political attention when it was referenced on page 776 and included as a footnote in a document launching negotiations for a new treaty at a meeting of over 190 nations in Bali in 2007. Rich nations have currently proposed cuts ranging from 8 to 14 percent below 1990 levels by 2020, with the European Union offering 20 percent cuts, or 30 percent if other developed nations participate. The text on page 776 suggests that developing countries should make significant changes by 2020 to reduce their emissions, which has caused a divide between rich and poor nations. Instead of implementing a sliding scale of cuts based on wealth, both sides feel overwhelmed by the expectations. It is uncertain how this deadlock will be resolved, with possibilities including the wealthy nations offering deeper cuts or the developing nations compromising in exchange for clean technologies and increased aid. Hare suggested that Russia, a key country that has not yet established a greenhouse gas target, could have a significant impact since its emissions are already approximately 30 percent below 1990 levels following the collapse of the Soviet Union. If Russia were to maintain current levels for a 2020 goal, overall promised cuts could increase to between 12 and 18 percent. However, some countries argue that cuts do not necessarily have to fall within this range, especially if future reductions are more substantial. Jonathan Pershing, the leader of the US delegation in Bonn and an author of the IPCC chapter that mentioned the 25-40 percent range, mentioned in a recent briefing that there are other possible trends to consider.