This satellite measurement shows that the steep warming of the 1980s to 2000s corresponded with over a 6 Watt per square meter reduction in the global average cloud coverage.
Not only does this change represent over a 6 Watt per square meter increase in incoming solar radiation (aka Sunshine), but also there is an associated reduction in down-welling IR radiation from back reflection off of cloud bottoms.
For this reason, Global Warming is rightfully called Global Brightening.
This increase in Sunshine is over 20x larger than the theoretical radiative forcing associated with rising CO2 concentrations.
The questions remains: What caused this cloud-cover decrease?
"Conclusion: We have proven that the GCM-models used in IPCC report AR5 cannot compute correctly the natural component included in the observed global temperature. The reason is that the models fail to derive the influences of low cloud cover fraction on the global temperature. A too small natural component results in a too large portion for the contribution of the greenhouse gases like carbon dioxide. That is why IPCC represents the climate sensitivity more than one order of magnitude larger than our sensitivity 0.24°C. Because the anthropogenic portion in the increased CO2 is less than 10 %, we have practically no anthropogenic climate change. The low clouds control mainly the global temperature."