Read here. (See updated chart with below information here.) Since publication of IPCC 2007 report, new research has been published with findings that non-greenhouse gas factors have significantly raised global temperatures, which were not recognized by IPCC. If these factors were properly accounted for, real greenhouse gas (CO2) global warming since 1950 would be 0.204°C versus the "reported" 0.702°C. That drops the per century rate of GHG warming from 1.17°C to a measly 0.34° C per century.
"Now, whether or not all of these impacts are as large as they have been reported, or whether they are totally independent of each other (as we have assumed), may or may not bear out as more research in done in the future. But, more research may just as well determine that these effects may be larger than reported, or may identify yet other warming influences. We can’t say for sure—nor can anyone else....But one thing that we can say for sure is that the IPCC’s statement that “[m]ost of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG [greenhouse gas] concentrations” is badly in need of reassessment. The current literature shows that it cannot be justified."
