Disruption of the global nitrogen cycle: A grand challenge for the twenty-first century : This article belongs to Ambio's 50th Anniversary Collection. Theme: Eutrophication

Abstract

Disruption of the global nitrogen cycle by humans results primarily from activities associated with food and energy production. Since the middle of the twentieth century, human activities have more than doubled inputs of nitrogen to the Earth's ecosystems. This new nitrogen is in chemically and biologically active forms (reactive N) and moves through the environment causing an array of health and environmental problems. Research published in Ambio for the past three decades has been documenting this major global-scale problem and has catalyzed the formation of a science-led initiative, the International Nitrogen Initiative (INI), which has informed policies to manage the global nitrogen cycle. Currently, gaps and opportunities in nitrogen pollution policies still exist and require new interdisciplinary science to help to place the nitrogen management challenge in the context of the other environmental grand challenges of our time including climate change and biodiversity loss because their solutions will be interconnected.

Keywords: Eutrophication; Global nitrogen cycle; International Nitrogen Initiative; Nitrogen management strategies; Nitrogen pollution policies; Reactive nitrogen.

Fig. 1

Low and declining oxygen levels in coastal and ocean waters. Map indicates location of 500 + coastal sites where anthropogenic nutrients (especially N) have exacerbated or caused O₂ dexclines to < 2 mg liter⁻¹ (red dots). After Breitburg et al. (2018), sourced from the World Ocean Atlas (2009)