If we’re assuming that market forces can put these companies out of business, then additional spending on security would hasten that. It would be even cheaper for them to just reduce pollution in the first place - their net gains from excessive pollution are less than our net losses from it, making this an externality problem. So with defense on the table, the equilibrium becomes for them to pollute less.

Increased costs to polluters should trickle down to our cost of living about as much as decreased costs have - so, it won’t at all. The polluters are getting the whole surplus here.

Fossil fuels have tremendous engineering advantages if one ignores pollution. It’s not a given that we can invent an ecologically sustainable alternative that will outperform fossil fuels if there are low internal costs to polluting.

Edit: oh and I’m totally joking and haven’t given this a lot of thought or anything