How would this work specifically?

Work would start in three dimensions immediately. Ecologically, people would take inventory of the entire planet, then calculate the ecosystem support required for an optimum human population. That area would be set aside in permanent reserves. That means zoning, e.g., the syngeo zones. Global planning and zoning would be based on known limits, as well as on known wilderness, cultures, common places, and domesticated landscapes.

Politically, people would create a new international body to regulate part of the planet for human use and the remaining half (or more) as a reserve for the wild planet itself.

Economically, people would decide on levels of development, as goals at first, for specific cultures.