> I saw on Google that it gets 6% brighter every 1 Billion years. That's a really long time, and I'm not sure what that even means anyway.

For our current situation, it means nothing.

The grandparent comment was referring to a period 100s of millions of years ago. Given that the sun's intensity has changed significantly on that scale, it's not appropriate to compare our current situation to that of something that happened 100s of millions of years ago.

For what it's worth, the atmospheric CO2 reduction that followed that period was associated with significant cooling and glaciation, which is further evidence that CO2 is a significant factor in determining global climate change. The grandparent comment was very disingenuous.