How much greenhouse effect is from water vapor compared to co2?

Question

So Co2 is 1/1000th of the greenhouse effect? so doubling CO2 would have what significant impact? I am confused.

Answer 1

The most significant factor in "global warming" is in the intensity of the sun's rays reaching the earth.  This is obvious by the stark difference between the climate at the equator and the climate at the north and south poles.  The effect of the angle of the sun's rays reaching the poles is so great, that there is no question what is responsible for global warming.

We all know water is a far more significant contributor to the greenhouse effect.  If you don't believe it, ask one of the world's most respected climate scientists:

" Q: Could you rank the things that have the most significant impact and where would you put carbon dioxide on the list?

A: Well let me give you one fact first. In the first 30 feet of the atmosphere, on the average, outward radiation from the Earth, which is what CO2 is supposed to affect, how much [of the reflected energy] is absorbed by water vapor? In the first 30 feet, 80 percent, okay?

Q: Eighty percent of the heat radiated back from the surface is absorbed in the first 30 feet by water vapor…

A: And how much is absorbed by carbon dioxide? Eight hundredths of one percent. One one-thousandth as important as water vapor. You can go outside and spit and have the same effect as doubling carbon dioxide." --Reid A. Bryson

Answer 2

The vast majority is from water vapor. CO2 is actually a very minor greenhouse gas.

Answer 3

Water is way more, but...

The "water cycle" recycles water between air and land and keeps the greenhouse effect from water under control.  It's very stable.

There is a similar natural "carbon cycle" that recycles CO2.  But it's a delicate balance and we're messing it up.

Look at this graph.

http://scrippsco2.ucsd.edu/graphics_gall...

The little squiggles are nature doing its' thing. CO2 falls a bit during summer when plants are active, and rises during the winter. The huge increase is us, burning fossil fuels (in addition to the shape of the graph, the increase numerically matches the increase in fossil fuel use). The scientists can actually show that the increased CO2 in the air comes from burning fossil fuels by using "isotopic ratios" to identify that CO2.  The natural carbon cycle buried carbon in fossil fuels over a very long time, little bit by little bit. We dig them up and burn them, real fast.  That's a problem.

Man is upsetting the balance of nature.  We need to fix that.

Answer 4

It is true that CO2 comprises almost 400 parts per million. It is also true that water vapor can comprise from 10,000 to 40,000 parts per million.  The popular theory about the greenhouse effect, is that the greenhouse gasses, COx, NOx, SOx, and particulates, form an inversion layer that allows the sun's heat to pass thru the atmosphere, but doesn't allow it to radiate back out, causing a continual heating where the inversion layer exists.  This heating warms the water to the vapor point, causing more and more of it to enter into the atmosphere, and even though there may be less actual cloud cover, in an area controlled by atmospheric inversion, the process continues to increase during the daylight hours.

What happens at night in these areas of inversion, is that a thick layer of clouds may form, creating an erie daylight condition called gloom.  What is interesting, is that the sunlight still continues to insolate the ground surface.  That means that the heat will continue to come through to slowly warm the earth which adsorbs the heat.  It is released at night, but the now well-formed cloud cover keeps much of the heat in.  And so the cycle goes, until the atmosphere gets so heavy with water vapor that the vapor droplets begin to coalesce with the particulates in the atmosphere and absorb the gasses present and it begins to rain.  Its a dirty rain at first, to wash the particulates out of the air...then it really comes down hard for a while until a balance occurs...

It is actually much more complicated that this, but the above is a simplistic mental sketch of how the cycle works...

Answer 5

CO2 comprises almost 400 parts per million.  Water vapor can comprise from 10,000 to 40,000 parts per million.  It is far more important, though I don't know exactly how much.  One of the theories with CO2 is that when CO2 increases, water vapor will also.  In fact they have found that when temperature increase in the tropics, cloud development decreased, meaning their are serious flaws in that theory.