You're back to that. It's not '3 trillion cubic tons'; it's not a drop of pee. It's 421 ppm.
First off; your math is wrong and not even using the correct units.
Second; nobody is arguing about how much 0.04% of the atmosphere is. Yes, we know it's a very small percentage of the atmosphere. Yes, we know adding another 0.04% doesn't feel like it will have an impact. But it does. I honestly don't know how someone can run a reef tank and not understand this. If you really think 400 ppm is so dilute as to not matter lets go ahead and add ONE PPM of something to your reef tank. Why don't we try copper? It will only take 15 drops in a 200 gallon tank to reach 1ppm. But it's so dilute it won't do anything, right? After everything dies, imagine adding 6,000 more drops. That's still only 400 ppm, less than the co2 content of the atmosphere. For goodness sake we measure phosphate and ammonia and a dozen other things in concentrations less than a single ppm and panic.
And if you insist on sticking with the disgusting comparison, that's 6,000 drops of pee in a single 200 gallon tank. You have the tools to measure this in your kitchen - it's 1 and a quarter cups of pee. In a single tank.
So just how much co2 is in the atmosphere? Each ppm represents 7.82 gigatonnes; and as of 2022 the concentration was 421 ppm. That's 3,292 gigatonnes. And a third of that has been added since the mid 1800s alone.
This is propaganda from the corporations doing the polluting. They want you to feel guilty so that you blame yourself instead of them. Remember shows like Captain Planet?