Status Updates From How the World Really Works:...

…without its use as the dominant nitrogen fertilizer (directly or as feedstock for the synthesis of other nitrogenous compounds), it would be impossible to feed at least 40 percent and up to so percent of today's nearly 8 billion people.

Four materials rank highest on this combined scale, and they form what I have called the four pillars of modern civilization: cement, steel, plastics, and ammonia.