Figure 8.3: Atmospheric concentrations of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) at Baring Head
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Source: National Institute of Water and Atmospheric Research.
Text description of figure
Figure 8.3 shows 3 line graphs showing the atmospheric concentrations of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) at Baring Head.
The concentration of carbon dioxide in the atmosphere measured at Baring Head has risen from 324 ppm in 1970 to 379 ppm in 2006. This is a steady trend with an average growth rate of 1.5 ppm per year. The concentration of methane rose steadily from 1989 to 1997 by 6.5 ppb each year. There is strong seasonal variation in methane concentration. Since 1998 concentrations of methane have leveled with a small decrease in recent years. The concentration of nitrous oxide shows steady growth from less than 312 ppb in 1997 to almost 322 ppb in 2007. The average annual growth rate is 0.9 ppb each year.
