The Shanghai conference was the start of a series of meetings under U.N. auspices to gather evidence for climate negotiators. Other gatherings will focus on the social and economic costs of global warming and how to reduce it. The series ends in April with the release of a huge report in Nairobi, Kenya. A key conflict in climate negotiations is a U.S.-led effort to reduce the impact of cuts. Washington wants to count carbon dioxide absorbed by forests and farmland against a country's reduction commitments.
Some European governments oppose that.
American cars, factories and power plants put out a quarter of the world's greenhouse gases, which also include nitrous oxide and methane. Other opponents of drastic cuts include oil companies and major coal producers such as Australia.