Global modeling of soil nitrous oxide emissions from natural processes

Nitrous oxide is an important greenhouse gas and is a major ozone‒depleting substance. To understand and quantify soil nitrous oxide emissions, we expanded the Community Land Model with coupled Carbon and Nitrogen cycles version 3.5 by inserting a module to estimate monthly varying nitrous oxide emissions between 1975 and 2008. We evaluate our soil N 2 O emission estimates against existing emissions inventories, other process‒based model estimates, and observations from sites in the Amazon, North America, Central America, Asia, Oceania, Africa, and in Europe. The model reproduces precipitation, soil temperature, and observations of N 2 O emissions well at some but not at all sites and especially not during winter in the higher latitudes. Applying this model to estimate the past 24 years of global soil N 2 O emissions, we find that there is a significant decrease (increase) in soil N 2 O emissions associated with El Niño (La Niña) events.