Nitrogen (N) is one of the building blocks of life: it is essential for all plants and animals to survive. Nitrogen (N2) makes up almost 80% of our atmosphere, but it is an unreactive form that is not accessible to us.
Humans and most other species on earth require nitrogen in a “fixed,” reactive form. Reactive nitrogen is necessasry for the food production process. Until the discovery of the Haber-Bosch process in the early 1900s, we only had access to naturally occurring sources of reactive nitrogen (such as manure and guano) for food production. The Haber-Bosch process--an industrial process through which we can fix reactive nitrogen--has allowed food production to keep up with the growing human population, but at a cost to the environment.
Today, humans create over 2 times as much reactive nitrogen as nature. In contrast, human activity contributes just 5-10% of CO2 emissions. Much of this reactive nitrogen has accummulated in the environment, where it causes a series of negative impacts to human and ecossytem health. Major sources of this reactive nitrogen include agriculture and the burning of fossil fuels. This nitrogen pollution causes profound environmental impacts, including smog, acid rain, forest dieback, coastal ‘dead zones’, biodiversity loss, stratospheric ozone depletion and increased greenhouse gases. It also affects human health, including respiratory disease and an increased risk for birth defects.