There are issues with the quote, and Communist countries do pollute, but if the argument is (as avgcorrection stated):
> Then it's the small task of changing the economic model of the entire developed (and less developed, and exploited) world. The model that all of the richest and most powerful people depend on.
Then yes, you're talking specifically about Capitalism at this point; avgcorrection is saying that we can't make this change because it conflicts with Capitalism.
;) Unless you're trying to imply that Communism is the driving economic force behind the entire developed world, which I'm going to guess is not something you believe.
I do think it's reasonable to ask whether the problem of human exploitation and the tendency for entrenched powers to cement their own power at the expense of the world is perhaps broader than one economic system and whether that harmful instinct might show up in multiple places and systems beyond only Capitalism. One could very reasonably argue (and I would argue) that Capitalism showcases just one manifestation of a human instinct that corrupts multiple economic systems including Communism.
But avgcorrection's criticism (as far as I can tell) was that we can't shift off of fossil fuels because that shift is incompatible with the driving economic model of our time: Capitalism. So I don't think the quote is inappropriate. It's easier to imagine the end of the world than to imagine the system avgcorrection is referencing (Capitalism) even temporarily bending in order to prevent that end. Whatever solution is proposed is only likely to be adopted if it doesn't conflict with Capitalist ends because Capitalism is fully willing to look directly at an incoming catastrophe, shrug its shoulders, and do nothing if the solution would decrease immediate profits.