Global N2O emissions from our planet: Which fluxes are affected by man, and can we reduce these?

Abstract

Summary: In some places, N2O emissions have doubled during the last 2-3 decades. Therefore, it is crucial to identify N2O emission hotspots from terrestrial and aquatic systems. Large variation in N2O emissions occur in managed as well as in natural areas. Natural unmanaged tropical and subtropical wet forests are important N2O sources globally. Emission hotspots, often coupled to human activities, vary across climate zones, whereas N2O emissions are most often a few kg N ha−1 year−1 from arable soils, drained organic soils in the boreal and temperate zones often release 20–30 kg N ha−1 year−1. Similar high N2O emissions occur from some tropical crops like tea, palm oil and bamboo. This strong link between increased N2O emissions and human activities highlight the potential to mitigate large emissions. In contrast, water where oxic and anoxic conditions meet are N2O emission hotspots as well, but not possible to reduce.

Keywords

• Biogeochemistry
• Environmental geochemistry
• Microbiology