A demographic crisis is a situation where the population of a territory, or the world, is not sustainable. One kind of demographic crisis is overpopulation.
Many developed countries have birth rates too low to sustain their own population. Russia in the 1990s, Germany and Japan are notable examples.
Minority population bomb
In many countries, minorities have higher fertility rates than majorities. This is the case in the United States and Israel.
This phenomenon can be cited in a racist context, to express minority population growth as a threat. Especially population growth among Muslims in Europe has been cited as a threat against Western culture .