It will be nasty but not so much I think, the world's population is most likely already much lower than previous believed.
Here's an article on Nigeria, supposedly the most populated country in Africa:
Summary * Nigeria's official population (~220-230 million) may be significantly inflated and could be closer to 170-180 million[1] * This overcount…
forum.effectivealtruism.org
And recently,
The Economist published an article about the overestimation of the world's population, claiming we could start to see a worldwide decline as early as 2050 iirc. (Some European and Asian countries already have a declining population)