A few years back out of control population growth was a big worry. Then along came the green revolution with its massive increase in food production and the worry disappeared.
The problem remains, however, that the earth is a finite space. And now the factor of limited space, as the population continues to explode, is being magnified by global warming. So one of the big factors of growing world wide rage is the same as what happens in a cage full of too many rats — massive violence.