Proposals such as this are going to turn off a lot of otherwise amenable people, like myself, who would support more extreme measures to control the climate. It belies a view that there needs to be some kind of world governance structure deciding who does and does not get to have children.
I really recommend, "DON'T PANIC — Hans Rosling showing the facts about population". He shows how family planning looks like in practice in countries like Bangladesh, so that westerners can imagine what are we talking about: https://www.youtube.com/watch?v=FACK2knC08E
Dealing with global warming is going bad and we should panic about that, but humanity is making great progress on controlling population growth.
There is really no issue with you having 3 children. Western population will be declining anyway as fertility rate in western countries is mostly below 2.
Just please, support political, systematical change in your country emission policy.