[parkinglot (OP)]

In a future (100, 200, 500, and 1000 years in the future specifically) where industrial and domestic pollution is totally unregulated, what does the composition of the atmosphere look like? And what do weather systems look like? I know this is an extremely broad question, I'm just looking for a few theories/ideas from folks smarter than I am. I'm wondering what kind of protection humans would need in this future. Is the main issue still CO2 and global warming? What about particulate pollutants? At what point does it become unsafe to fly because of density of smog? Based on my limited knowledge I don't think even an extreme greenhouse gas effect future would be quite like Venus because of our more limited volcanic activity. So what does it look like? I recently read that Aerosols were actually holding off some of the effects of global warming by reflecting some of the suns energy and now that we have reduced them we're feeling a more extreme increase in temperature and that got me thinking about these questions. What does that horrible unregulated polluted future look like? And specifically, what chemicals do y'all think would be in the atmosphere in large quantities?
Thanks!

[alancalverd]

Think back to London in the 1950s, or Los Angeles in the 1960s, for a view of the near future with unregulated use of dirty fossil fuels. Respiratory toxins will limit human activity and thus the consumption of fossil fuels long before the carbon dioxide concentration becomes significant.

Natural water fog (i.e low cloud) can severely limit flying, but a proper London pea-souper makes even road transport dangerous: I recall being unable to see both ends of the car in a yellow-green smog in 1952.

Poliicians get excited by particulates nowadays, but persistent city smog needs sulphur dioxide (London) or nitrogen oxides (LA) and unburned or partially oxidised hydrocarbons to really stick around and stink.

I think Saab demonstrated how a lean-burn diesel engine with a catalytic exhaust converter could actually produce exhaust that was cleaner than the intake air. This suggests that ambient air itself could become self-inflammable or explosive, given the right pollutants in suficient concentration. Wouldn't that be fun?