The rapid increase in the production of reactive nitrogen via the Haber-Bosch process correlates closely with the increase in world population from about 2.6 billion in 1950 to over 6 billion in 2000 (figure page 78). Based on the figures from Dawson and Hilton (2011), over 2 billion tonnes of reactive nitrogen was manufactured in that period. The enormous increase in artificial fertilizer production catalyzed by the Haber-Bosch process has altered the flow and balance of the nitrogen cycle at a global scale, representing a roughly 150% increase in new reactive nitrogen added annually to the environment compared to the pre-industrial period (figure page 80). Starting in the 1940s when man-made generation of reactive nitrogen was only around 4 Mt/yr, manufacture of reactive nitrogen began rising at an exponential rate.
From collection: Green Economy in a Blue World - Full Report