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12.Ecosystem
normal
$CO_2$ content of atmosphere has increased in the last $150$ years from
A
$25$ to $35\ ppm$
B
$270$ to $340\ ppm$
C
$0.027$ to $0.34\ ppm$
D
$0.2 $ to $0.3 \ ppm$
(AIIMS-1997)
Solution
(b) $CO_2$ conc. was about $ 270 $ ppm in $ 1750$ and $368$ ppm in $2000$. The rise has been due to large scale deforestation (for grazing land, cropland or urban estates), change in land use and large scale combustion of fossil fuels.
Standard 12
Biology
