Anthropogenic nitrogen plays a double role in climate change

Increased nitrous oxide emissions from fertilised soils offset climatic benefits from carbon sequestration.

Since the mid 1900s, human activities, especially the application of fertilizers in agriculture, have doubled nitrogen inputs to terrestrial ecosystems such as agriculturally used areas, but also forests and wetlands. This has two opposing effects on the climate system: on the one hand, ecosystems  are thus able to absorb more carbon dioxide from the atmosphere, which lessens the greenhouse effect. On the other hand, the nitrogen-rich soils emit more "laughing gas", which is significantly more detrimental to the climate than carbon dioxide, thus cancelling out the carbon benefits of anthropogenic reactive nitrogen. © Pixelio

Human nitrogen additions to the soil may reinforce the greenhouse effect.  Nitrogen additions tend to boost plant growth, so that terrestrial ecosystems absorb more carbon dioxide from the atmosphere. But recent studies have shown that they also stimulate nitrous oxide release from the fertilised soils – a much stronger greenhouse gas than carbon dioxide.

According to a new paper by researchers around the team of Sönke Zaehl from the Max Planck Institute for Biogeochemistry, nitrogen's detrimental effects on the climate roughly correspond to its climactic benefits.

In fact, the scientists' findings suggest that the negative impacts of nitrogen may even slighty prevail.

Human activities have more than doubled nitrogen inputs to the terrestrial biosphere since the 1860s through increased atmospheric nitrogen deposition and the application of fertilizers in agriculture.

Nitrogen is an essential nutrient for plant and microbial growth, and one of the key limiting nutrients in many natural ecosystems. But  anthropogenic perturbations of the nitrogen cycle through the additions of fertilisers are known to affect the terrestrial sources and sinks of greenhouse gases such as carbon dioxide (CO2) and nitrous oxide (N2O), better known as "laughing gas".