I think you're poorly informed, or perhaps in denial about how far down the road we already are: [0] [1] [2]
It's essentially too late for your or my hypothetical descendants to have any effect on "the greater good". The IPCC says either we cut _worldwide_ CO2 emissions by 50% in the next 11 years, or it's game over for +1.5C scenarios: all coral reefs die, along with most of the fish, crop yields down 40% in some places, mass migration and resource wars are likely.
So basically I think it's too late for any "greater good" to come from my having kids, and I believe it's immoral to bring a life into a doomed world just to suffer.
I get the risks. I’m just not a quitter. Somebody has to show up and try and I’m willing to nominate my descendants for that. And I’m pretty sure they’ll be okay with my choice. Many people throughout history have been born into some pretty fucked up situations (slavery, etc.) and decided that life was worth living.