Give up population growth. This really is key but too often overlooked.
What you are proposing is thus an imperialist dictate on African and Asian countries, which is an obvious no go.
Instead you should advocate for improved standards of living and flourishing economies in all these countries, which is strongly correlated with stabilizing population levels.
Africa, with 1.+2 billion inhabitants, has a tiny carbon footprint compared to the US (which as less than 1/3 of Africa's population).
Source: https://unfccc.int/files/press/backgrounders/application/pdf...
So either we tell them that, sorry, but they have to stay dirt poor and also to stay away from their rain forests even if they starve, or the aim is to eradicate poverty on the planet, but in that latter case their resources footprint (this is more general than carbon alone) is bound to increase.
That's why the global population is a key factor in fighting climate change and protecting the environment.
Yes, the entire world cannot buy larger cars than what we need them for, we cannot fly around the world on vacations, we cannot throw away half the food we produce, we cannot buy clothes to use them once, and so on.
Such needless things, often more related to consumption culture than living standards, is responsible for a large portion of emissions.
Not only that, but we live in societies with an enormous capital in infrastructure built up from previous emissions.
I think westerners should at least start thinking about not emitting CO2 just for the fun of it, before telling others to not have too many children.
But the key issue with your reply is that this is not 'us' doing this versus 'them' doing that.
We must reduce CO2 emissions and we must stop population growth. Both 'we' mean humankind as a whole.
I really don't understand this disconnect between the message of urgency about the environment and the climate, and the widespread complacency about an actual root cause of the issue (as illustrated by your comment), which is population growth: "Oh it's slowing and will probably stabilise at 11 billions... that's fine. On the other hand, we must be emissions-neutral and stop using plastics by tomorrow." That's totally incoherent.
We just need to learn to be efficient.
The world is not empty. It's either exploited to cater for human needs or wilderness that should be protected at the point we've reached.
Math: 327 million US ppl * 274 UK ppl per sq km / 35 US ppl per sq km.
Granted, a few pockets of wild forests left, Amazon, parts of Central Africa, New Guinea, Siberia. Under intense development pressure. Hard to call that "most of the world".
Southern California is an inhospitable desert, but tens of millions of people live there nonetheless.
PS. Mars colonization is folly.
Natural population growth is not occurring in rich countries