Wow, I am totally at a loss to understand what you are asking.
Global warming is not due to carbon dioxide?
You can easily calculate how much warmer the earth is because of the presence of carbon dioxide and other greenhouse gases in its atmosphere, compared to a black body at 1 AU from the sun (about 33 degrees C). Without global warming, mainly due to carbon dioxide and water vapor in the air, the earth would be MUCH colder.
And you are correct that carbon dioxide is not the only greenhouse gas. There are many more. Such as water vapor and CFCs and HFCs and nitrous oxide and methane and so on. But CO2 does contribute, a lot.
We can't see light in a vacuum? Well I guess if I passed light through a vacuum I would not see it until it bounced off something. But if I was in the vacuum and the light went into my eye, then I would see it. I just don't understand your statement.
And I have no idea what those two statements have to do with the first question about scientists and quizzes.