Intergovernmental Panel on Climate Change. News Release, May 9, 2011
Close to 80 percent of the world‘s energy supply could be met by renewables by mid-century if backed by the right enabling public policies a new report shows.
The findings, from over 120 researchers working with the Intergovernmental Panel on Climate Change (IPCC), also indicate that the rising penetration of renewable energies could lead to cumulative greenhouse gas savings equivalent to 220 to 560 Gigatonnes of carbon dioxide (GtC02eq) between 2010 and 2050.
The original IPCC press release can be found at http://srren.ipcc-wg3.de/press
The link above however is much more readable.