Humanity is facing an unprecedented dilemma — how to feed a burgeoning population while resources decline and the ability of the Earth’s ecosystems and atmosphere to absorb pollution diminishes. A scientific breakthrough made a hundred years ago is at the heart of the problem. The Haber-Bosch process enabled the use of fossil energy to transform atmospheric nitrogen into a form that plants can use. The resulting product, nitrogen fertiliser, enabled the Green Revolution, a massive increase in food production. Previously, nature had fixed atmospheric nitrogen mainly through leguminous plants, blue-green algae and lightning. But now, using fossil energy, the flux of anthropogenic nitrogen into the atmosphere, soils and water has increased tenfold over all natural sources. 1 Synthetic nitrogen has allowed the human population to reach double the 3.5 billion that could have been sustained without it. Since the discovery, population growth and the increase in nitrogen fertiliser production […]