Table 4. Sources of N2Oa

Source	NH	SH	Global
Soil	4.601	2.931	7.532
Ocean	1.546	2.052	3.598
Anthropogenic sources	1.701	0.270	1.971
Post-forest clearing soil + biomass burning	0.257	0.195	0.452
Total sources	8.105	5.448	13.553
aUnits are Tg N/yr. Anthropogenic sources include animal excreta, industry, fossil fuel burning, biofuel burning, and agriculture. The latitudinal distributions of the sources are plotted in Figure 6.