Solarpunk

I probably should have phrased it as "have less children" :)

My list was based on the book "How Bad Are Bananas" which goes into depth about the carbon emissions from various things, including children.

I'm not 100% sure that attributing the emissions of a child to their parents is correct 'accounting'. Maybe only their emissions until age 18? Still, all the emissions caused by that child and it's descendants would not have happened if it wasn't for the decision their parents made to create it. Accounted for this way, there is no doubt this is the most impactful decision someone in a developed country can make (that was the framing the OP used so I went with that) but it is not the most likely to happen, most practical or most moral option.

That is the problem with the whole CO2 footprint. You chosing not to fly is reducing your CO2 footprint, but airline companies will respond with ad campaigns and cries for state help and then other people will take your seat. But if you think it from a CO2 footprint perspective, you are responsible for CO2 produced by your actions. You take the decision to take that long-distance flight to Bali and that adds to your lifetime CO2 emissions. You put solar on your roof and that reduces your lifetime CO2 emissions considerably. And yes, an additional human on this planet will produce a lot of CO2 in his lifetime. And you as a couple are deciding to put him onto this planet - so from that perspective it is totally a good way to reduce your direct CO2 impact by deciding to birth another human.

https://en.m.wikipedia.org/wiki/Voluntary_Human_Extinction_Movement

Can you explain why me not having a child would directly harm people with disabilities? I really struggle to see the logic here - even if you want to point out that we need younger generations in order to care for the elderly, there is still a record number of humans living on the planet right now and I struggle to understand what an individual child would change here