The invention of the Haber-Bosch process in 1913 enabled us to increase the efficiency and scale of food production by using ammonia to create nitrogen fertilizers for crops. Studies show that nearly 50% of the nitrogen found in human tissues originated from Haber-Bosch. It has been described as the “detonator of the population explosion”, with global population increasing from 1.6 billion in 1900 to 7.8 billion today.

This process relies on fossil fuels to work on a large enough scale to support the current population, and it is extremely energy-intensive. We all know by now that fossil fuels are responsible for climate change, ocean acidification, and a multitude of other ecological crises. We also have vast ocean deadzones as a result of chemical fertilizer runoff.

If we continue with business as usual, climate change and ecological collapse will kill billions of people. On the other hand, without Haber-Bosch, billions would starve. So humanity is in a bit of a pickle, to say the least.

Malthus was right—he just got the timing wrong because he didn’t predict the industrial revolution.

Long story short, I would say Haber-Bosch and the industrial revolution were the two biggest factors in population growth. Without these, humans numbers would have probably never broken 2 billion.