Is it the sun, not carbon dioxide or anything else that is driving changes in the climate

Venus is completely enveloped in clouds, and it has an atmosphere that consists almost entirely of carbon dioxide, as well as a 900 deg F surface temperature. There is a correlation there, and I agree that clouds make the surface warmer. So does carbon dioxide. The earth is a long way from Venus, but it is clear that CO2 is a stronger influence on the cloud cover and the resulting surface temperature than subatomic particles from distant supernovae, or even from the sun. In fact, I do not understand the mechanism that you have described. It seems to me that solar radiation is a much stronger influence than supernovae remnants. What clouds and CO2 do is to prevent the infrared waves that result from that radiation from escaping into space. So that multiplies the effect of the initial radiation. I am drawing no conclusions about the source of that CO2 on earth. We probably get far more greenhouse gases from volcanoes than we get from cars. But excessive CO2 is a primary cause for increased surface temperatures.

There is too much evidence that climate change is directly linked to the increase in greenhouse gases produced by human activity beginning with the Industrial Revolution. Saying the cause is outside of human activity is simply denial and worse than useless.

Think aboutt it a minute - if increased solar activity reduces the number of particles that can form clouds, then there should be a direct correlation between the 11-year solar cycle and the climate. Guess what - there is NO relationship.
The 11-year solar cycle is well-documented and studied, so if there was some relationship between the solar cycle and global warming, don't you think at least one scientist somewhere would have seen that...?

The Sun is the driving engine of weather and climate. The current global warming IS anthropogenic, but Earth has been a lot warmer in the past and will be warmer in the future because of changes in the eccentricity of Earth's orbit.