In 1950 the world population was about 2.5 billion and approximately six decades after the number went to 7 billion. That means a multiplication factor of almost three while today there are some very optimistic numbers for sixty years with a multiplication factor of less than one, so three billion more to a total of 10 billion in 2070.
The population doesn't matter when the society is evolved enough to provide basic elements to every individual without destroying the habitat, making distinctions in the task of assigning resources or causing harm to other species. Sadly at an extreme, this is not what happens today.
With the advent of the "middle class" and of course above this line, now billions are promoting the so-called unsustainability as it arrives with a great degree of consumption below logic where necessities aren't considered but the act of entering in the consumerism wheel buying the same products over and over and forcing the social system to handle the massive quantity of despised materials, creating waste in the same proportions. You could easily imagine what could happen if the entire world population enters in this wheel today, or with 10 billion.
To achieve prosperity and a sustainable development, each person must be analyzed in terms of consumption per day, with the perfection of mathematics, being sure of to not leave chance to errors because otherwise the catastrophe is ensured, dragging to the hole to other species. A hole created by lacking of rationality, planning.
Reasons enough to understand that the civilization today claims for international cooperation toward to establish control with policies for adapting the population to the available possibilities since the security of the life depends on it. What kind of international government could permit what's happening today with places wasting the same resources that others need to survive and lose their life for it?
It's difficult to find something more technically unfair that the inequality of opportunities. Then, another view is trying to count the world population with the people that experience it. In fact is an index that qualifies the entire species.