World population growth is slowing down, but there are still problems.

Population growth is slowing down so some worry that there aren't enough young workers for retires. Immigration can solve that problem for democracies where people want to move.

Population growth can also overwhelm housing and infrastructure leading to anti immigration sentiment rising in most of the world's democracies, however.

World population growth needs to slow down even more and another big change is the rising prosperity and expectations of prosperity around the world. That can use more energy and resources while contributing to resentment and instability, thus the world, as a whole, is spending more and more on military spending.