Once again...

Global warming is not driven by the total population of Earth. It is driven by greenhouse gas emissions, which are proportional to high levels of resource consumption. 

If everyone on Earth had the carbon footprint of the median human being, we would not be in the midst of global climate change.

To stabilize and restore Earth's climate, we do not need to reduce the total number of people. Rather, we need to reduce the carbon footprint of the fraction of us who are high-consuming.