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Re: Global Warming



Regarding Brian's answer to Jim's question:

2) What are/is the major gasses which contribute to global warming?

CO2, Methane.

The answer to this question depends on just what Jim means by the word
'warming' in the phrase 'global warming'. If it is meant to signify the
increase in the average planetary surface temperature over the value it
currently has (or has had in the recent past), then Brian's answer is
probably correct. But if it is meant to signify the increase in the
average planetary surface temperature over the value it would be in the
absence of any greenhouse gases, so that it is thought to be a measure
of the total planetary greenhouse effect, then the answer is incorrect.
The great majority of the planet's total ~34 deg C greenhouse effect,
i.e. global warming (over the otherwise temperature without any
greenhouse effect) is due to *water vapor* in the atmosphere. As I
recall, maybe faultily, the contribution of H2O to the planetary
greenhouse effect is something over 25 deg C worth of the total. In any
event the sum of the effects of all the other greenhouse gases is small
compared to the effect of H2O. Besides H2O, CO2 & CH4, the next most
relevant greenhouse gases in terms of their contribution to the total
planetary greenhouse effect are O3 & N2O.

David Bowman
David_Bowman@georgetowncollege.edu