Why don't we hear about water vapor contributing to global warming more than we hear about CO2 ???

Question

Since water vapor is a greenhouse gas that contribute to global warming more than CO2 does, why don't we hear about it more?

Why all the focus on CO2 instead?

Is the media and government simply waiting for us to have fuel-cell cars that only output water vapor before starting to focus on it?

Answer 1

As others have noted, water vapor is a feedback, not a forcing.

A forcing is something which can directly alter the planet's temperature.  A feedback is something which can only amplify a forcing.

In the case of water vapor, its atmospheric concentration is dependent on the atmospheric temperature.  A hotter atmosphere can hold more water.  So unless you make the atmosphere hotter, water vapor levels will not change, and thus water vapor cannot cause global warming.  However, if you do make the atmosphere hotter (for example by adding CO2 to the atmosphere), then water vapor levels can increase and add to the warming - hence it's a feedback.

That's why all the focus is on CO2.  See Myth #9 at the link below for further details.

Answer 2

Because Water Vapor is only the results of the global warming, while the root cause is the CO2 volume in atmosphere. The Water Vapor cannot be eliminate as long as we have sea.

The water vapor produce from sea due to the rising temperature and act as catalyst but not the root cause

Answer 3

Because scientists KNOW water vapor can't be causing global warming.

Excess water vapor in the atmosphere falls out very rapidly, so it can't create warming.  Excess CO2 stays there for years.

When CO2 initiates warmiing THEN the warmer atmosphere can hold more water vapor, and make these worse.  In technical jargon, water vapor is a feedback, not a forcing.

Scientists understand this one quite well.  More about it here:

http://environment.newscientist.com/chan...

Answer 4

This whole global warming thing based on CO2 levels is just a scam. It has been proven without a shadow of doubt that CO2 levels in the atmosphere follow climate change not the other way round . If you take a clear winters night and you are south enough to have frosts , you will have a frost. CO2 levels are the same day and night. But if it clouds over you don't get a frost. Now tell me CO2 holds the heat in, rubbish.

I'm down south in a winter and it's just as cold this year as any other , in fact, our May was the coldest in ten years.

Global Warming, c**p.

Answer 5

Water vapor is harder to tax

Answer 6

Water vapor is a feedback, not a forcing.

Answer 7

If all cars were spewing out high quantities of anything there would be some residual effects, yes.  But if you study the nature of the various greenhouse gases, and how each behaves in the atmosphere, you have your answer.

A few links for you to investigate so you can see for yourself.

Answer 8

The amount of water vapor in the atmosphere is a function of global temperature, but since there is a natural sink (rainfall) and source (oceans) for water vapor it simply enters or leaves the atmosphere in response to changes in the global temperature. The residence time for water in the atmosphere is very short.  This is not true for carbon dioxide, its residence time is measured in centuries.  So, while water vapor can enhance global warming, it cannot cause it. That's why we worry about CO2 and not H20.

Answer 9

Water is H2O. There is no carbon in water and when it evaporates it becomes hydrogen and oxygen which are not greenhouse gases. CO2 is carbon and that is where we have a carbon footprint.

Answer 10

1 - human activity is not directly adding or removing significant amounts of water vapour

2 - CO2 slowly builds-up over the eyars (thus affects are cumulative); water vapour lasts a few days

3 - There is no limit to how much rain can fall, but there is a limit to how much extra CO2 the oceans and other sinks can soak up

4 - CO2 is responsible for two-thirds of the additional warming caused by all the greenhouse gases emitted as a result of human activity

Water vapour does play a huge role in climate, but is not a driver of climate change; it is a consequence. Like all consequences, it has further consequences itself (increased warming due to greenhouse effect but also decreased warming due to clouds reflecting sunlight).

It is important for us to understand water's role when modelling climate change but if we didn't put the CO2 in the atmosphere in the first place, we wouldn't need to worry about the water.

P.S. to Pat j

Nice, well rounded logic supported by facts to do with GLOBAL warming - thanks!

"has been proven without a shadow of doubt" - got anything to back this outrageous claim up?

When talking about decade- and century-long global trends, what relevance does the fact that "CO2 levels are the same day and night" - the greenhouse effect is about how the atmosphere traps the sun's energy - of course the sun is still important; days will always be warmer than nights!

Clouds, frosts, your local experience (in one year) are examples of weather, not climate!

Answer 11

I tend to agree with you.

Although, in my opinion there is no such thing as a 'Greenhouse Gas'.

Water is the only thing that can have any influence in any way whatsoever.

This is because of it's ability to form clouds of small water droplets which can only moderate rapid changes in temperatures.

Cloud cover during the day will slow ground temperature rise by blocking the sun, and keep overnight temperatures from plummeting rapidly by keeping the normal radiation from the surface to escape back into space.

It still amazes me to see how many people(some claiming to be scientists), actually believe that CO2 is a cause of so-called 'Global Warming, when even the simplest of experiments would prove them wrong..

Some of their insane comments would seem to suggest that this planet never had any clouds or weather of any kind until the 1850's!

These same people seem to believe that CO2 is an enemy and not the life giving force that it actually is!

People love to be frightened for some perverse reason.

The media knows that sensationalism is profitable, simple science and facts are not.

There is far too much money to be made out of people's gullibility by exploiting their ignorance.

If there was no money to be made, this subject would have stayed in 'Academia Land' where it belongs.

I would like to ask anyone to explain how 17 ounces per ton of an invisible gas could have any influence on temperatures.

Answer 12

There are some calculations about how irrigation continually increases the water vapor of the atmosphere and its subsequent modification of earths greenhouse process. Some estimates out the total amount of heat captured by anthropogenic water vapor are at about 314.25 terawatts. That seems like a lot of energy but when you divide that by the surface area of the planet 10^15 × 0.510 m2 you only get about .6 W/M^2, that's enough to make a difference, the question is, can anthropogenic water vapor feedback on it's self, (or amplify itself)?