Global projections for anthropogenic reactive nitrogen emissions to the atmosphere: An assessment of scenarios in the scientific literature

Most long-term scenarios of global reactive nitrogen (Nr) emissions to the atmosphere are produced by Integrated Assessment Models in the context of climate change assessments. These scenarios indicate that these global Nr emissions are likely to increase in the next decades, followed by a stabilization or decline. Crucial factors for future Nr emissions are the development of the underlying drivers (especially fertilizer use, animal husbandry, transport, power generation and fires), air pollution control and climate policies. The new scenarios made for climate change research and assessment, the Representative Concentration Pathways – RCPs, cover a smaller range of possible Nr emission projections than the literature, as they all assume progressive air pollution control. A more focused development of scenarios for air pollution may be needed to improve both the relevance and quality of the scenarios for research and assessment of air pollution (and possibly short term climate change).