8.3.1 Trends since 1990
Globally, agricultural CH4 and N2O emissions increased by 17% from 1990 to 2005, an average annual emission increase of 58 MtCO2-eq/yr (US-EPA, 2006a). Both gases had about the same share of this increase. Three sources together explained 88% of the increase: biomass burning (N2O and CH4), enteric fermentation (CH4) and soil N2O emissions (US-EPA, 2006a).
During that period, according to US-EPA (2006a; Figure 8.2), the five regions composed of Non-Annex I countries showed a 32% increase in non-CO2 emissions (equivalent to 73 MtCO2-eq/yr).The other five regions, with mostly Annex I countries, collectively showed a decrease of 12% (equivalent to 15 MtCO2-eq/yr). This was mostly due to non-climate macroeconomic policies in the Central and Eastern European and the countries of Eastern Europe, the Caucasus and Central Asia (see Section 8.7.1 and 8.7.2).