CO2 CH4 N2O Atmosphere life time(yr) 120 14.5 120 Direct GWP (Global Warming Potential 1 24.5 320 Pre-industrial concentration 280ppmv 0.8ppmv 288ppbv Current annual increase (%) 0.5 0.9 0.25 Major Agricultural Source Deforestation Ruminants Synthetic N fertilizers Wetland rice Animal Excreta Biomass burning Biological N fixation Percentage of global source stemming from agriculture 30 40 25 Predicted change 1990-2020 - + +

Table 1: An overview of agricultural greenhouse gases with the trends as currently predicted (adapted from IPCC, 2009).