All a matter of which externalities you're willing to overlook.

80 years ago, the solution to pollution was dilution - nobody gave a flying F if you dumped raw sewage in the ocean so long as you did it far enough offshore that it didn't come back to the beach... That works when you've got a total human population under 2B and most of them aren't burning significant fossil fuels... with 8B of us and rising, and half of us capable of hopping in a jet plane for a round-the-world trip whenever we feel like it, the pollution really does start to matter.

War is one of those side effects of civilization, and I haven't seen the war yet that gives a F about what it does to the environment, beyond maybe - just maybe sometimes - not wanting to kick off global winter.