Emission trends

For 2005, agriculture accounted for an estimated emission of 5.1 to 6.1 GtCO₂-eq (10–12% of total global anthropogenic emissions of GHGs). CH₄ contributed 3.3 GtCO₂-eq and N₂O 2.8 GtCO₂-eq. Of global anthropogenic emissions Errata in 2005, agriculture accounted for about 60% of N₂O and about 50% of CH₄ (medium agreement, medium evidence). Despite large annual exchanges of CO₂ between the atmosphere and agricultural lands, the net flux is estimated to be approximately balanced, with net CO₂ emissions of only around 0.04 GtCO₂/yr (emissions from electricity and fuel use in agriculture are covered in the buildings and transport sector respectively) (low agreement, limited evidence) [8.3].

Trends in GHG emissions in agriculture are responsive to global changes: increases are expected as diets change and population growth increases food demand. Future climate change may eventually release more soil carbon (though the effect is uncertain as climate change may also increase soil carbon inputs through high production). Emerging technologies may permit reductions of emissions per unit of food produced, but absolute emissions are likely to grow (medium agreement, medium evidence).

Without additional policies, agricultural N₂O and CH₄ emissions are projected to increase by 35–60% and ~60%, respectively, to 2030, thus increasing more rapidly than the 14% increase of non-CO₂ GHG observed from 1990 to 2005 (medium agreement, limited evidence) [8.3.2].

Both the magnitude of the emissions and the relative importance of the different sources vary widely among world regions (Figure TS.19). In 2005, the group of five regions consisting mostly of non-Annex I countries were responsible for 74% of total agricultural emissions [8.3].

Figure TS.19: Historic and projected N₂O and CH₄ emissions (MtCO₂-eq.) in the agricultural sector of ten world regions, 1990–2020 [Figure 8.2].

Note: EECCA=Countries of Eastern Europe, the Caucasus and Central Asia.