One chemical process feeds roughly half the people alive today

In 1909, chemist Fritz Haber found a way to force nitrogen from the air to combine with hydrogen into ammonia under huge heat and pressure; engineer Carl Bosch then scaled the reaction up to industrial size. The Haber-Bosch process broke agriculture's oldest limit, turning atmospheric nitrogen into synthetic fertilizer on a massive scale. Today it's estimated to sustain nearly half the world's population, food production that couldn't otherwise exist on the same amount of farmland.

— Fritz Haber & Carl Bosch, Haber Process — First demonstrated 1909