Wealthy nations, as history's biggest polluters, should cut greenhouse gas emissions by 40 percent from 1990 levels by 2020, China says in a policy document on climate change. The government also rolled out fresh help for solar power and other «green energy.» The reductions China is calling for are based on the principles of «historical responsibility and fairness,» the position paper says, and set a hard line ahead of international negotiations on addressing global warming, according to AP. A U.N. conference set for December in Copenhagen aims to draft a new agreement on controlling carbon dioxide and other heat-trapping greenhouse gases that scientists say are causing the Earth to warm. Delegates will meet in Bonn, Germany, next month to begin discussing the text of that agreement. China's position paper was posted Thursday on the Web site of the National Development and Planning Commission, the country's main economic planning agency. Meanwhile, the government announced new support for solar and wind power and other renewable energy sources. In a meeting Thursday with provincial officials, the Ministry of Finance promised 38 billion yuan ($5.6 billion) in subsidies to promote wider use of wind and solar power and encourage the use of energy efficient cars and appliances, state-run media reported Friday.