Vaughan Pratt, did you just tell manacker he was wrong about the rate of increased in CO2 levels because if you take his rate back in time far enough, it gives too low a value? That’s how I’m reading your comment, but…
That’s stupid. Almost any rate of change given is an estimation. If you extrapolate out far enough, they’ll usually give you a wrong answer. It’s a meaningless point, and it certainly doesn’t invalidate anything. The most it can do is allow you to tell manacker he’s wrong to say “the past” is the past because he’s only looking at one part of the past, not “the last 200 years.” Not only is it a stupid point based purely on semantics, it begs the question of why limit ourselves to only the last 200 years? Maybe the next time manacker talks about the “[p]ast increase of atmospheric CO2 level,” you should tell him he’s wrong because of what things were like millions of years ago!
I hope I’m just misreading you. If not, you’re contradicting manacker based entirely upon a stupid and meaningless point rather than simply saying something like, “When you say ‘the past,’ you’re only talking about the last XX years, right?”