Renewable energy could meet 77 percent of the world’s power needs by mid-century if the right policies are put in place, according to a new report by the UN’s Intergovernmental Panel on Climate Change. According to the report, such a dramatic shift to renewable energy would produce a cumulative carbon dioxide emissions savings of 220 billion to 560 billion tons between 2010 and 2050, or up to a one-third reduction of projected emissions. In 2008, only about 13 percent of the world’s energy came from non-fossil fuel sources, including the burning of firewood in developing nations, hydropower, and solar and wind power. But the report predicts that renewable energy technologies will become increasingly attractive economically if governments put a price on their environmental impacts, including greenhouse gas emissions and pollution. Should governments embrace renewable energy programs, concentrations of CO2 in the atmosphere can probably be held below 450 parts per million, a major goal of the IPCC. “It is not the availability of the resource, but the public policies that will either expand or constrain renewable energy development over the coming decades,” said Ramon Pichs, co-chairman of the IPCC’s Working Group III, which compiled the report.