6.4.3.3. Increases in Atmospheric Nitrous Oxide Concentration

The observed increase in atmospheric N2O concentrations at the present time implies that an excess of 3.9Mt/a is emitted to the atmosphere. Since pre-industrial times N2O concentrations have increased by approximately 13% (Machida et al., 1994), and now stand at about 310ppbv (Figure 6.6).