Just like I have said, CO2 forcing has been overstated by about 30% because there are unknown natural forcings that we (climate scientists) have attributed to anthropogenic carbon dioxide emissions.
http://www.worldclimatereport.com/index.php/2011/11/08/a-new-lower-estimate-of-climate-sensitivity/
http://wattsupwiththat.com/2011/11/09/climate-sensitivity-lowering-the-ipcc-fat-tail/
WUWT also covered this earlier this week, but the link to the pdf file is broken. The author must have removed the file due to excessive traffic.
http://www.worldclimatereport.com/index.php/2011/11/08/a-new-lower-estimate-of-climate-sensitivity/
http://wattsupwiththat.com/2011/11/09/climate-sensitivity-lowering-the-ipcc-fat-tail/
WUWT also covered this earlier this week, but the link to the pdf file is broken. The author must have removed the file due to excessive traffic.