text: The IPCC says in its latest report: "The differences in radiative forcing estimates between the present day and the start of the industrial era for solar irradiance changes and volcanoes are both very small compared to the differences in radiative forcing estimated to have resulted from human activities. As a result, in today's atmosphere, the radiative forcing from human activities is much more important for current and future climate change than the estimated radiative forcing from changes in natural processes. "(Ch.2, p.137) This position will be more closely considered. The change in the total solar radiation since 1750 is estimated by the IPCC to 0.12 (-0.06 / +0.18) W/m2 (Ch.2, Table 2.12). This value is of the order of the relative change per decade of satellite measurements. ACRIM has measured as for the cycles 21-23% or 0.5W/m2 0037. The absolute error is about the satellite but with 3W/m2. How could you determine, however, without satellites in the past such small changes is not explained. To a completely different result, however come Solanki and Fligge (CRL 26 (1999) 2465). Their reconstruction shows the next graphic: Both the absolute and the relative values are more than one order of magnitude larger than the values specified by the IPCC.