Green house gases (Water Vapor)?

Question

There is a lot of talk about hydrogen fuel cells to help stop CO2 emissions in the atmosphere, but wouldn't releasing water vapor from hydrogen fuel cell cars on a grand scale be much worse for the environment because it blocks in much more sun light than CO2...about 25 times as much I think...something thats been puzzling me...does it fall into those solar windows or not?

Answer 1

While your facts are partially true your mixing current atmosphere  ratios with one to one ratios eg:

water vapour only traps more heat (nb it traps and reflects, trapping heat is the major environmental concern) because the atmosphere is mostly water vapour were as CO2 only makes up a small percentage. adding a little more water vapour wont have any  major effect (twice the amount of water vapour is still better than half the current CO2)

Also CO2 traps 4 times as much heat as water vapour

H2O (water vapour) is removed from the atmosphere very rapidly (rain) were as CO2 can remain in the atmosphere for decades or longer.

so yes water vapour will have no major effect on the atmosphere and climate and is by far better than CO2 from fossil fuels.

Answer 2

no - water vapor is highly variable becasue it falls out of the atmosphere very quickly in a couple days- whereas CO2 stays in the atmosphere for decades - water vapor does not make it to high altitudes as easily- this is where heat exchanges with space.

http://www.realclimate.org/index.php/arc...

Answer 3

Carbon Dioxide.

Answer 4

While technically you're right, but water vapor is a condensable gas at normal atmospheric conditions.  And there is so much water in the atmosphere that the amount from fuel cells would be like a handful of bees in the Superdome.