Several hundred scientists from across the globe will gather in Ludwigshafen, Germany, next week to discuss a simple topic: "A hundred years of the synthesis of ammonia." As titles go, it is scarcely a grabber. Yet the subject could hardly be of greater importance, for the gathering on 11 November will focus on the centenary of an industrial process that has transformed our planet and threatens to bring even greater, more dramatic changes over the next 100 years.

The ammonia process – which uses nitrogen from the atmosphere as its key ingredient – was invented by German chemist Fritz Haber to solve a problem that faced farmers across the globe. By the early 20th century they were running out of natural fertilisers for their crops. The Haber plant at Ludwigshafen, run by the chemical giant BASF, transformed that grim picture exactly 100 years ago – by churning out ammonia in industrial quantities for the first time, triggering a green revolution. Several billion people are alive today only because Haber found a way to turn atmospheric nitrogen into ammonia fertiliser. "Bread from air," ran the slogan that advertised his work at the time....