Chiming in late, and most likely beyond the scope of modding (quite new to the game, and not entirely sure what's possible yet), but I have a fondness for throwing ideas out there. Sure a space faring society would be *able* to lick pollution, but there are many examples in sci-fi where it's not done because it's not expedient to do so. My personal suggestion, whether it be for a later version, or maybe for a mod (a few ideas in my head about how it could be done with buildings) would be a combination of a slider (or optionally a set of buildings, with the mid-level choice being none at all)... call it sustainability, and a counter for pollution. Low sustainability would raise the pollution counter, but give a production and economy bonus. Mid-level sustainability would give no bonus, but wouldn't add to the counter. High would give penalties to production and economy, but decrease the counter. As the pollution counter increases, penalties to population growth, max population, morale and loyalty start growing as well, and extremely high values could give a chance for catastrophic effects (sudden die-off, especially if population was at max, and the max dropped... improvements destroyed, terrain becomes unusable, etc.)
Trends either way throughout the civilization could also have more universal diplomacy, influence, morale and ethical effects - especially as either your citizens die off due to your greed, or you annex someone else's messes and clean them up, respectively.
Like I said, quite possibly beyond the scope of modding, but it'd be cool. And if it's not moddable, it would make a good (IMHO) addition for some future expansion pack.
