I'm going to assume most people have at least a passing familiarity with the ideas of Thomas Malthus regarding human population and the planet's resources.
According to him, a society's population "adjusts" to accommodate the available supply of food and natural resources. People might learn how to raise more food more efficiently, but often the mechanisms of "adjustment" are things like war, disease, and famine. That's a simplistic summary, but you get the drift. (If you want to learn more, the internet is actually a good place to start looking. Even Wikipedia, which I don't normally recommend, offers a good primer on Malthus.)
Anyway, unless you're living under a rock, you know that demand for food and water have risen to historic highs, thanks to rising population and global affluence. Naturally that raises the question: How will Malthus' theory play out over the next few decades? Was he right? Completely off mark? Has technology altered his fundamental premise?
There's a fascinating article in this morning's Wall Street Journal about relevance, meaning, and importance of Malthusian economics in today's world. If you spend any time pondering stuff like, oh, high food prices, soaring costs for brewing materials, globalization, and other interesting-and-complicated-but-depressing topics, it's worth a look.