Their money comes from somewhere, and that somewhere is many times a source of great suffering. If they had to make that somewhere adhere to rules or abide by law or stop exploiting others - humans or nature - it would cost them a great amount of money.

If that's true it would mean fixing this injustice would just even out who gets to have what. It would not meaningfully reduce consumption, certainly not enough to make a huge difference in CO2 emissions.

(There might be one exception to that: reducing warfare. War is a gigantic waste twice over: tons of energy to fight, tons of energy to rebuild all the stuff we break. But I doubt eliminating warfare would be enough alone to cut emissions enough to matter.)

There's only two ways to reduce CO2 emissions by a large amount in a durable lasting way:

1. Replace CO2 emitting sources of power with those that don't emit CO2.

2. Destroy the middle class.

Actually I guess there's a third: kill a lot of people.

Anything less is a rounding error that won't make much of a difference.

I'll take option 1. Luckily the laws of physics say we can do it. We just need the political will. There's also precedent. Many developed countries' emissions per capita has been falling while growth has actually continued (in most cases) and standard of living hasn't moved much. We just need to do a lot more of what works.