In this podcast by social impact careers organisation 80,000 Hours, engineer David Denkenberger argues that it would be possible to feed everyone even in the event of a disaster that disrupts agriculture, such as a nuclear winter or asteroid strike.
Denkenberger outlines several methods for feeding people in such as disaster, including using bacteria to digest natural gas, growing mushrooms on wood or other organic waste, and breaking cellulose down into sugars using enzymes.
Listen to the episode here. Denkenberger co-founded ALLFED, which researches alternative food sources. See also the Foodsource building block What is food security? and the research library entry Comment: Electric food – new sci-fi diet could save our planet.