The X-istence of Externalities

Pingry, commenting on this post, writes

And so if continued growth can reduce pollution and environmental harm after some point, why should third parties be subjected to dangerous spillover costs before that point?

Should they just "deal with it" so that future generations can face less spillover costs after reaching a certain point?

Or should polluters be forced to internalize their spillovers so that all innocent people can be spared such a market failure?

Why assume that greenhouse-gas...