Fifty Inventions That Shaped the Modern Economy

by Tim Harford

Imagine the heat of a wood-fired pizza oven, with the pressure you’d experience more than a mile under the sea. To create those conditions on a scale sufficient to produce 160 million tons of ammonia a year—the majority of which is used for fertilizer—the Haber-Bosch process today consumes more than 1 percent of all the world’s energy.5 That’s a lot of carbon emissions, and it’s far from the only ecological concern. Only some of the nitrogen in fertilizer makes its way via crops into human stomachs—perhaps as little as 15 percent.6 Most of it ends up in the air or water. This is a problem for several reasons. Compounds such as nitrous oxide are powerful greenhouse gases. They pollute drinking water. They create acid rain, which makes soils more acidic, which puts ecosystems out of kilter and biodiversity under threat. When nitrogen compounds run off into rivers, they likewise promote the growth of some organisms more than others; the results include ocean “dead zones,” where decaying algae blooms consume oxygen, suffocating marine life.7