Our present global warming is not at all unusual by the standards of geological history, and it is probably benefiting the biosphere.
But the sun is not driving
the present global warming because there has been no clear trend in sunlight for 50 years.
That statement was a lie but his testimony became the foundation of
the present global warming movement.
Burning fossil fuels has been identified as the main reason for
the present global warming.
The idea is, if the change in surface temperature over that period is affected by changes in cloud cover, but changes of the surface temperature associated with the ocean warming are small, then changes in cloud cover must be driving
the present global warming.
The present global warming is happening because extra carbon dioxide is being released from burning fossil fuels.
It happens to be the major (not the only) cause of
the present global warming, but at other epochs other causes have been more important.