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Greenhouse Effect
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6.4.8. Summary

With the exception of stratospheric ozone, all greenhouse gases discussed throughout section 6.4 have increased in concentration in the atmosphere over the last 200 years since the beginning of the Industrial Revolution. Pre-industrial and current concentrations of the key greenhouse gases, and their recent rates of increase (IPCC, 1995), are displayed in Table 6.2.

Table 6.2. Pre-industrial and 1992 atmospheric concentrations of greenhouse gases

CO2

CH4

N2O

CFC-12

Pre-industrial concentration

280ppmv

700ppbv

275ppbv

zero

Concentration in 1992

355ppmv

1,715ppbv

310ppbv

503pptv

Rate of change of concentration during 1980s

1.5ppmv/a

13ppbv/a

0.75ppbv/a

20pptv/a

Atmospheric adjustment time

50-200 yrs

12-17 yrs

120yrs

102yrs