Please explain water vapor's role in global warming to me?

Question

I understand about greenhouse gases and the greenhouse effect. I don't understand exactly what water vapor does. I'm a middle-schooler, and I attempted to research it, but it was kind of confusing. Water vapor is the most powerful greenhouse gas, but there's a reason people aren't worried about it. That's basically all I've learned.

Answer 1

Water vapor only stays in our atmosphere for about 10 days which means it doesn't accumulate and we cannot affect the amount of it directly.

On the other hand, emitted CO2 can stay for centuries in our atmosphere, Methane for decades. As long as we emit more than earth can handle, it continues to accumulate and increasing our "greenhouse effect".

Answer 2

Water is pretty good at retaining heat. That is why warm ocean currents so greatly influence climates around the world. Most scientists would agree that water is by far the most important of all our natural resources, kinda like the sun in it's degree of necessity.Why would anyone dispute it's importance in our atmosphere?

Answer 3

Water vapor is the most powerful of the greenhouse gases. Studies vary, but it is thought to control 60 to 95% of all the greenhouse effect. The reason many studies omit water vapor is it does not conform to their agenda. Man does not change the level of water vapor. So, those who want to use global warming as a means of taxing individuals omit water vapor and focus on CO2.

You will hear studies of man made CO2 being about 35% of the CO2. This is true, but what you need to realize is that yes we contribute about 35% of all the CO2, BUT if we include water vapor, we contribute less than 1% of the CO2 gases.

At your age, this is confusing, but realize that our effect on climate is very very small. Imagine a plane flight from LA to NY. Comparing this to our contribution to greenhouse gases is the same as the airplane leaving LA and getting about 1 mile from it's starting point (barely off the runway). The rest of the flight is all natural. That is how little our effect on climate is.

Answer 4

Water vapor is very good at absorbing thermal radiation.  As the Earth warms, more vapor will be in the air (basic thermodynamics).  It is also clear that as the earth warms, the oceans will give off Carbon Dioxide.  If these two gases were the primary thing driving global temps, the cycle would be unstable.  More heat, more water vapor and CO2, then on and on.  This does not occur.  Other factors are at work.

Answer 5

water vapor  basically  just traps heat  energy  like  any other greenhouse gas .i bet you know the specific heat and latent heat capacity   of water.so, water like any other greenhouse gas just traps the heat within its molecules ,thereby increasing the heat in the  surroundings.but when water evaporates it uses up 80 calories of heat for the evaporation of every i  gram of water .thats why we sweat

Answer 6

This is an web site that attempts to explain water vapor:

http://www.solarnavigator.net/greenhouse...

Quote:  "The role of water vapor -

Water vapor is a naturally occurring greenhouse gas and accounts for the largest percentage of the greenhouse effect, between 36% and 90% "

Note the chart about Carbon Emissions.  The growth rate of Greenhouse gases is EXPONENTIAL.  Ask your self = Why is not CO2 also growing exponentially and why was CO2 slowly increasing before the 'industrial boom' and has continued slowly and consistently since before 1900.

CO2 is a heavier gas that settles to the ground/oceans to be reabsorbed into soil/water.

http://volcanoes.usgs.gov/Hazards/What/V...

Whereas water vapor in clouds can remain aloft for several days at a time = witness here:

http://www.weather.unisys.com/satellite/...

Answer 7

Water vapor is not the most powerful greenhouse gas (it's actually a very weak one), but it is responsible for the largest amount of the greenhouse effect on Earth (36-66%) because there's so much of it in the atmosphere.

The reason we don't worry about it with regards to global warming is that the amount of water vapor in the atmosphere depends on the temperature of the atmosphere.  As long as the planet isn't warming, the amount of water vapor in the atmosphere won't increase, so it can't cause warming.

Water vapor is what we call a feedback.  When something else causes the planet to warm (like increased carbon dioxide in the atmosphere), the atmosphere can then hold more water vapor.  That increase in water vapor will then cause the planet to warm a bit more (that's the feedback part), until it reaches a new equilibrium.  Basically it makes global warming worse, but it can't initiate warming.

See the link below for further details.