Rapid population growth — combined with our highly unbalanced distribution of wealth — and its obvious need for more resources (water, energy, food) may lead to a breaking point beyond which civilization becomes unsustainable.
Simply put, if you don’t have any water to drink or food to eat but your neighbors do and won’t share, you and your buddies are going to yank it away from them. Social unrest is not a joke.
The NPR Report with links to the Study
EVERYTHING around me indicates humanity needs to make rapid changes in their cultural and economic values.