As CO2 science's Idsos report:
"Fang et al. come to the following conclusions.
First, "global warming is an objective fact," but there is "great uncertainty in the magnitude of the temperature increase."
Second, "both human activities and natural factors contribute to climate change, but it is difficult to quantify their relative contributions."
Third, with regard to the IPCC claim that "the increase in atmospheric concentrations of greenhouse gases (including CO2) is the driving force for climate warming," they note the following four problems:
- "It remains unclear how the human and natural factors, especially the aerosols, affect the global temperature change,"
- "Over the past century, the temperature change has not always been consistent with the change of CO2 concentration," since "for several periods, global temperatures decreased or were stable while the atmospheric CO2 concentration continuously increased,"
- "There is no significant correlation between the annual increment of the atmospheric CO2 concentration and the annual anomaly of annual mean temperature," and
- "The observed significant increase of the atmospheric CO2 concentration may not be totally attributable to anthropogenic emissions because there are great uncertainties in the sources of CO2 concentration in [the] atmosphere."
Fang, J.Y., Zhu, J.L., Wang, S.P., Yue, C. and Shen, H.H. 2011. Global warming, human-induced carbon emissions, and their uncertainties. Science China Earth Sciences 54: 1458-1468.