Figure 8: Records of changes
in atmospheric composition. (a) Atmospheric concentrations of CO2,
CH4 and N2O over the past 1,000 years. Ice core and firn
data for several sites in Antarctica and Greenland (shown by different symbols)
are supplemented with the data from direct atmospheric samples over the past few
decades (shown by the line for CO2 and incorporated in the curve representing
the global average of CH4). The estimated radiative forcing from these
gases is indicated on the right-hand scale. (b) Sulphate concentration
in several Greenland ice cores with the episodic effects of volcanic eruptions
removed (lines) and total SO2 emissions from sources in the US and
Europe (crosses). [Based on (a)Figure
3.2b (CO2), Figure
4.1a and b (CH4) and Figure
4.2 (N2O) and (b)Figure
5.4a]
