Feel free to put up an estimate then.
>I don't think you can actually put a number on this waste.
Well that just makes it clear you're only interested in your feelings/vibes as opposed to anything objective.
To give a really simple upper limit: 36.8 billion tonnes per year. Because that's the current total global CO2 emissions per year. And we can be pretty sure that ads are less than that, or at least not more.
I agree with your assessment of the grandparent comment.
So, even if advertising was technically neutral (which is clearly not the case), it would still be an ecological cataclysm.
One would even argue that the whole climate emergency is created by our advertise/consume culture.
Pulling an "estimate" out of your ass isn't exactly any more objective than admitting that attempting to estimate it is futile.
"I know that I know nothing" and all that.
I don't think you can actually put a number on this waste.