Figure
4.2: Change in N2O abundance for the last 1,000 years as
determined from ice cores, firn, and whole air samples. Data sets are from:
Machida et al. (1995); Battle et al. (1996); Langenfelds et al. (1996); Steele
et al. (1996); Flückiger et al. (1999). Radiative forcing, approximated by a
linear scale, is plotted on the right axis. Deseasonalised global averages are
plotted in the inset (Butler et al., 1998b).
