A severe disaster could cause total collapse of society and lack of food. Think like the aftermath of a full nuclear war between two large super powers, or an electromagnetic storm hitting earth, or a man made virus that wipes out half the population and has the other half hiding indoors scared to go outside - borders closed and massive quarantines.<p>None of these things is particularly likely to happen IMO. But if they did happen, you suddenly have a large portion of people not being fed. When people aren&#x27;t being fed, you get uprisings, wars, and desperate people joining the roving bands of marauders that the article talks about.<p>But man, the Earth currently produces so much food. It&#x27;s incredible really how much we can do with so few humans, with modern agriculture. Most of it goes to animals, and in a time of need we could slaughter them and eat the corn directly.<p>It would be really, really hard to seriously damage the food output of Earth - or at least first world countries. And it&#x27;s only going to increase with technology like genetic engineering, super efficient robot greenhouses, or microorganisms bred to produce things like sugar 20x cheaper than conventional agriculture.