Name: Jim
Status: Student
Grade: 9-12
Location: NY
Country: United States
Date: Summer 2009
Question:
With CO2 only able to absorb infrared radiation in only
three narrow bands of frequencies totaling to, at most, an 8%
absorption of the entire infra red spectrum, how can it be in any
way responsible for global warming given it is a trace gas at 380
ppm?
Replies:
Jim,
While you are correct that CO2 absorbs in a few, narrow bands of infrared,
the issue is not so much what CO2 absorbs (and re-radiates as heat via
collisions with other gaseous molecules or as IR emission), but rather the
increase of CO2 gas since the industrial era began that is being considered
as a contributor to global warming. Water is also a greenhouse gas and absorbs
at a higher range of IR spectra. But we have no data stating that the amount of
atmospheric water has increased since we started measuring. CO2, however, has.
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