I find it awesome (not in the good sense) that the air my parents breathed as children contained substantially less carbon than the air I breathe today. I've also read that the weight of carbon we've released into the atmosphere exceeds the weight of all the built world we've created on the surface of the Earth.

That is to say that we've already altered the atmosphere immensely. Watching Carl Sagan or reading James Hansen's work the the 80's makes it clear that we had a good understanding of the consequences even then. The bill is now coming due and if we can't pay it, then obviously we need to find some way to dodge it.