Global trends toward scarcity and conflict threatened the human experiment. Reversing these trends requires doing something that has never been considered -- rapid population decline (RPD.)
If everyone chooses "one child per family" the resulting rapid population decline would create increasing abundance and increasing peace. Even these extreme measures, and some extraordinary advancements in technology may not prevent the mass starvation, and genocide which is already happening and which will get worse before our over extended conditions abate.
Implementing one child per family behaviors is difficult but not impossible. The implementation is comparable in design (if not magnitude) to getting people to stop smoking on airplanes. This was accomplished by using the fact that "sharing smoke was unkind/unfair to others." and by building a critical mass of compatriot believers that eventually, through social pressure and sanctions, changed smoker's behaviors.
Note that banning smoking on airplanes began with changing the "beliefs" of non-smokers -- not changing the "behaviors" of smokers. Non-smokers realized that second hand smoke was unpleasant, unhealthy, and unnecessary. They began to make their opinions heard.
If we follow this route, to implement RPD, we have to get a lot of people to "believe" that having a second child is like sharing stuff that should not be shared. They need to understand the implications of choosing multiple child families extend beyond the individuals taking the procreative behaviors.
We need a large group of people on earth to believe the second child behavior, taken universally, creates trends toward scarcity and conflict. And conversely, to believe the one child behavior, taken universally, creates trends toward abundance and peace. Our challenge is to get people to believe that one child per family makes the human experiment more viable, and two children per family reduces viability.
The implementation of RPD begins with a few people, who believe these truths, recruiting people from the 6 billion who think otherwise. That is, from the six billion who believe:
While the RPDer's task is to recruit one of these individuals to an RPD belief, there are easy and hard candidates. The RPDer's least productive candidate is a friend or family member, who is about to make a child-bearing decision. These individuals, culturally and genetically focused on the immediate personal benefits of a new child, find it most difficult to see and include the future benefits or liabilities that also accrue to the human experiment from that decision.
The RPDer should begin recruiting a person who has a stake in future benefits created by RPD and does not have to pay its implementation costs. They should focus on a person who lovers a child and has learned that that child will have to live in one of two futures -- one heading for abundance and peace, the other heading for scarcity and conflict. The RPDer should focus on a person who is not planning to have any more children themselves.
These people number in the billions. If we recruit all of them, we create the belief-consensus "RPD is probably the best course for the human experiment." If the belief-consensus "sharing-smoke was injurious to those not smoking" eventually lead to smoking bans on airplanes, then the belief-consensus, "sharing your second child is injurious to everyone's future," can implement rapid population decline. The viability of the human experiment depends on it.