Alas! The devil is in the details. The same problem that the cap-and-trade carbon scheme has. How do you deal with people or nations that ignore it?
The reproduction end would be easiest. Sterilization in exchange for a certificate that could be sold to the highest bidder. Carbon? As most of the worlds population is becoming urbanized, all products have to be brought into cities and could be assessed carbon points. The problem of rural people burning wood, distilling alcohol fuel, etc would be minimal and the effort and ingenuity that would go into it would minimize the carbon release. The bigger burning, such as peasant farmers burning off forests, would have to be policed. . At the industrial level, it would be easiest to enforce. People would tend to buy the more durable products to conserve their carbon allowance. There would naturally be more emphasis on repairing things than throwing away and buying new. A car, a bicycle or a pair of shoes would be more desirable if designed to last the owners lifetime..
It is already being done by people who want to do it. I drive a 49 year old car that gets over 35 mpg. I have boots that I’ve worn over 30 years, resoling as needed. I live in a 3500 square foot house that only requires 2 cords of firewood to heat (plus solar input). My farm machinery runs on biodiesel which I produce myself. I’ve made a concious choice to not be a parent. It’s just a matter of setting up the incentives to make other people want to live in this way.
Maybe give a larger carbon allowance to people who don’t live in cities? Or not count any fuels that you produce personally?
I don’t claim to have all the answers. Just running this up the flagpole and see who salutes it.