A global emissions inventory for ammonia (NH3) has been compiled for t
he main known sources on a 1 degrees x 1 degrees grid, suitable for in
put to global atmospheric models. The estimated global emission for 19
90 is about 54 Tg N yr(-1). The major sources identified include excre
ta from domestic animals (21.6 Tg N yr(-1)) and wild animals (0.1 Tg N
yr(-1)), use of synthetic N fertilizers (9.0 Tg N yr(-1)), oceans (8.
2 Tg N yr(-1)), biomass burning (5.9 Tg N yr(-1)), crops (3.6 Tg N yr(
-1)), human population and pets (2.6 Tg N yr(-1)), soils under natural
vegetation (2.4 Tg N yr(-1)), industrial processes (0.2 Tg N yr(-1)),
and fossil fuels (0.1 Tg N yr(-1)). About half of the global emission
comes from Asia, and about 70% is related to food production. The reg
ions with highest emission rates are located in Europe, the Indian sub
continent, and China, reflecting the patterns of animal densities and
type and intensity of synthetic fertilizer use. The overall uncertaint
y in the global emission estimate is 25%, while the uncertainty in reg
ional emissions is much greater. As the global human population will s
how considerable growth in the coming decades, food production and ass
ociated NH3 emissions are likely to increase as well.