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q |
The
atmospheric concentration of methane (CH4) has
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increased
by 151% (1060 ppb9) since
1750 and
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continues
to increase.
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q |
The present
CH4 concentration has not been exceeded
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during the
past 420,000 years.
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q |
Slightly more than half of current CH4 emissions
are
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anthropogenic (e.g., use of fossil fuels, cattle,
rice
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agriculture
and landfills).
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