The UN estimates between 4 and 5.5 depending upon the lifestyle. The Global Biodiversity Assessment, concludes:
The current global population is approximately 6 billion. The trend of growth rate is declining and may turn negative this century. Estimates of carrying capacity range from 1 to 40 billion people, depending upon whom you ask, but perhaps the statement is more revealing than it would at first seem.
Thats how many people it will support, the way they intend to run it.
They won't have enough people left to take care of the planet.
A single kingdom; who will be king?