Global warming - What role does water vapor really play?

Scientists say man-made CO2 causes global warming; climate skeptics insist that water vapor is responsible. Here's why both assumptions are true.
Without water vapor average temperatures would be up to 30 degrees Celsius lower/ Credits: Reuters

Here are the perfect ingredients for a conspiracy theory: water vapor is the most important factor influencing the greenhouse effect but doesn’t feature on the UN’s list of greenhouse gases responsible for anthropogenic global warming.

Critics of the idea of man-made global warming love this simple fact and have turned it into one of their most potent arguments to sabotage decisive climate action.

So why doesn’t the UN’s climate body the International Panel on Climate Change (IPCC) list water vapor as a greenhouse gas? It’s because water vapor does not by itself increase temperatures. It amplifies already occurring warming.

Water vapor’s role in the Earth’s climate system is defined by the very short time it remains in the atmosphere and actively traps heat. While additional CO2 from factories or airplanes can remain in the atmosphere for centuries, extra water vapor will only remain a few days before raining down as water.

The concentration of water vapor in the atmosphere is in equilibrium. The atmosphere can only hold more water vapor if overall temperatures increase. So a small warming effect caused by human CO2 emissions will increase the amount of water vapor in the atmosphere.

The added water vapor leads to even more warming, thus amplifying the CO2 warming effect. Water vapor follows temperature changes, it doesn’t cause or, as climatologists say, ‘force’ them. As a feedback effect, water vapor is comparable to a car’s turbo charger that increases a motor’s power.

However, the amount of water vapor in the atmosphere changes regionally. While there is virtually no water vapor above deserts or the Arctic and Antarctic regions, the air above the equator can consist of up to four percent water vapor.

In humid equatorial regions, where there is already a strong natural greenhouse effect, additional CO2 and water vapor have little impact on local climate. The opposite is true in cold, dry places, which is one reason why warming is much more pronounced in Polar regions.

Concentration matters

Regional differences aside, the atmosphere contains on average only 0.4 percent of water vapor and ten times less CO2. This relatively small concentration is another argument often cited to refute the idea of man-made global warming. How can CO2 cause rising temperatures, skeptics demand, if it only accounts for 0.04 percent of the atmosphere?

Again the riddle is solved easily.

Oxygen and nitrogen are the most abundant elements in the Earth’s atmosphere and make up 99 percent of it. But neither of the two gases traps or emits heat.

This is why water vapor is responsible for most of the natural greenhouse effect. Scientists estimate that without water vapor average temperatures would be up to 30 degrees Celsius lower. CO2, on the other hand, is responsible for a much smaller but still substantial amount of the natural warming effect.

If things remain like this, we could continue living on a cozy, warm planet. But too much of a good thing is often bad. CO2 levels have increased from 0.028 percent of the atmosphere to about 0.04 percent since the Industrial Revolution. This has led to a temperature increase of about 0.7 degrees Celsius so far.

About half of this warming could be due to feedback warming from water vapor, estimates the IPCC. But it would not have happened without the added CO2 pumped into the atmosphere. CO2 is the guy robbing the bank, water vapor is just the getaway driver.

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Comments (31)

Kenneth Lynes: 21.05.2015, 16:01

Well this assumes a lot and I think that directly putting water vapor into the atmosphere from airplanes burning fuel is very important. Before 9/11 it was possible to see the cloud patterns caused by jet planes flying at approx 38,000ft where each pound of fuel produces 5 pounds of water vapor. I estimate that an average jet is burning about 15,000 pounds of fuel and hour so that is 75,000 pounds of water vapor per hour being injected into the atmosphere at 38,000 ft. It was estimated that before 9/11 there were just under 5000 planes in the air at any given time over the USA. Cloud patterns could be discerned from satalite photos. After 9/11 we have reduced the number of planes to about 4000. (that may be a wrong assumption) but this remains a major problem. Normally there is very little water vapor at that altitude and only major thunderheads ever get over 30,000 ft. That is why the planes fly at 38,000 ft to get over the weather.
Also there is the constant use of irrigation and sprinkling now which puts over a billion gallons of water into the air every year. The use of wells to provide this water is causing a concern with the auquifer under the midwestern US. There are people who have studied this and can provide more information than I am able to recall here. But it is causing a shift in weather patterns without involving any CO2 at all!
My opinion is that it is all about taxing the CO2 and not clear science showing that water vapor is the cause of this weather problem.
In the 1990's I read that by that time, Texas had through the making of man-made lakes, swimming pools, exceeded the surface area of the lakes in Minnesota. Do you think that tendency has abated any?
It used to be that the sun heated up rocks on the Texas landscape and that heat was trapped near ground level for the most part, but now it is being used to evaporate huge amounts of water. That is transfering huge amounts of energy into the atmosphere along with that water vapor. I think that the water has to absorb about 1500 btu/lb to vaporize. So all that energy is now going into the atmosphere where it can alter the weather patterns and create stronger storms and more of them; exactly what we are experiencing now.

devbahadurdongol.blogspot.com: 29.11.2014, 05:14

Only purpose of the Quito protocol (only a propaganda or misinformation, jargon, cant, hoax and so on.) is for monopolizing the industry by the developed rich countries – saying indirectly to the poorer countries to stop industrialization; and, instead they would support the developing world by donations.

The main reason for global warming is due to the mistake done by human being for explaining the rain cycle wrong way that it occurs by the evaporation of the sea water. If it were so, now-a-days we should have rains more often than in the old days – global warming and expansion of the sea surface, both are favorable for evaporation needed for rain cycle. Sea surface temperature (average 15C) is not hot enough to lift water vapour to form cloud needed for the rain cycle. If that is possible we will have rains all the time, (even during winter we have that temperature in Nepal on the average).

We are making more and more land areas drier and drier by urbanization - covering land by concretes, black top roads, deforestation, and expanding deserts. So evaporation from the land areas is decreasing, as a result cooling of the land areas is decreasing significantly. Land areas are hotter than sea surface temperature.
We can control climate or present climate change is reversible just by determining how much land surface area of the earth to keep moist. More the land surface moist, the more rain cycle and cooler earth surface.

I shall be grateful to you if you could go through my blog for details and share with your friends.


Ozone depletion is not possible. Ozone as such can't exist as a layer. It is extremely unstable and heavier than O2. It breaks into oxygen atoms as soon as it forms (if not kept pressurized in a closed container).It is formed when oxygen molecules breaks into atoms with heat of high temperature (UV). Stratosphere is tremendously cold zone and extremely low pressure. Ozone formed breaks down into oxygen atoms as soon as it forms and releases heat. Even at sea level at NTP ozone is unstable. So ozone layer exists only in theory. Intermittently forming of ozone will continue until the oxygen is in the atmosphere and we receive UV from the sun. So ozone depletion is not possible. Ozone formation is a step to return heat back to space.
It is not ozone that blocks heat but O2 and in the process O3 is formed to release the heat absorbed by O2

Don't blame CFC (too scarce and too heavy to reach the stratosphere) for thinning stratosphere. In reality, Millions of jet flights everyday are consuming too much of oxygen of the layer.

devbahadurdongol.blogspot.com: 29.11.2014, 05:12

1. Green house. It requires solid transparent materials to form a green house.
2. GASES are freely moving molecules.
3. Gases can't form green house.
4. They can't be fixed to make walls / roof of a structure like 'green house'.
5. All matter / gases in Nature can hold Heat, so they can absorb heat like any gas e.g. CO2.
6. Convection method of heat transmission. Heat is always transmitted from higher to lower temperature.
7. O2 is 700 times more than CO2.
8. N2 is 2700 times more than CO2.
9. CO2 is not a pollutant. We carry the gas in our blood since birth and live throughout
the life with the gas.
10. Plants use the gas to prepare food. Then, HOW CAN THE GAS BE A POLLUTANT?
11. If GW were due to 'green house effect" (GHE), the upper layer of the Troposphere (our climatic atmosphere) should be warmer than the flat land areas because warm air goes up. So the top of the MT. Everest should be hot zone. The earth would have never been colder than the beginning 4 billion years ago.
12. Our atmosphere is not closed like a green house.
13. Our climatic atmosphere (Troposphere) should be always warm as the Sun always shines on the half of the Earth.
14. It wouldn't be cold during night (after the sun set and before the sun rise).
15. Minimum temperature is recorded about half an hour earlier than the sun rise.
16. We know it is always colder during night than during sunny days.
17. REFLECTION: gases don't reflect. They are transparent. Light pass through too small particles.
18. Materials become opaque when they reflect light.
19. Every molecule radiates absorbed heat when the surrounding is colder. It absorbs heat when the surrounding is hotter.
20. Foggy, smoggy, and cloudy days are colder than bright sunny days.
21. Gases are not layered in the Troposphere; it is a homogenous mixture of gases. If it were layered the heaviest gas, CO2 would be at the bottom not on top. Then animals wouldn't survive. We need O2 to be alive.
22. Gases of atmosphere should be still (no breeze, no wind) to be layered. Breezes, winds, hurricane, tornadoes, convection current or any motion thoroughly mixes all the gases.
23. Molecules of fluids move upwards when heated and downwards when cooled – the convection current.
24. CO2 is transparent, colorless, odorless, and heaviest gas of the atmosphere. It does not make shadow as clouds do.
25. If something does not allow going out means does not allow getting in as well. GHE applies only with the solid transparent materials like glasses and plastics not for the fluids (gases and liquids).
26. Methane is negligible, only traces.
27. Insulation traps heat partly. Gases alone can't trap heat. Gases can't work as an insulator in the open space. Our atmosphere is not insulating the earth. it should be air tight for effective insulation. The clothes we put on, the four walls and roofs etc. work as insulator, lesser the passage for air to pass through in and out the more effective is the insulation.

# Physical properties of fluids (gases and liquids) and atmosphere don't support them on GHG idea at all scientifically. GHG / GHE idea is fake.
(Just because you (NASA and IPCC) did not know or could not explain the cause of CC you are creating fake, imaginary, false, spurious and so on science to mislead the world. GW is not the problem but water.
Here is the explanation for the cause of the CC. I challenge all the scientific institutions / organizations especially NASA and IPCC that support GHG / GHE idea to prove my scientific analysis is wrong. CC due to gases is impossible instead they are helping the earth to cool down by convection method of heat transmission.)

So they don't have proofs. My Scientific analysis is 100% proof

So gases are not responsible for global warming but cooling the earth.

Only purpose of the Quito protocol (only a propaganda or misinformation, jargon, cant, hoax and so on.) is for monopolizing the ind

devbahadurdongol.blogspot.com: 29.11.2014, 05:10

CC wouldn't be solved if the world is after gases. NASA / IPCC are misleading the world by accusing gases for CC.

Why are people talking only about consequences and effects of climate changes instead of solution to climate change? NASA / IPCC are misleading the people by accusing gases for CC.


I am not CC denier. BUT I defy GHG idea.

First prove gases cause global warming. Can you?
GH gas idea is fake, ridiculous, imaginary, false, spurious, hoax and so on. Gases can't form green house. So, green house effect due to gases is impossible. They are actually helping the earth to cool down by convection method of heat transmission. Gases have freely moving molecules, so you can't fix any fluid to make a structure. CAN YOU?? Shame on you IPCC / NASA !!!!

Only purpose of the Quito protocol (only a propaganda or misinformation, jargon, cant, hoax and so on.) is for monopolizing the industry by the developed rich countries – saying indirectly to the poorer countries to stop industrialization; and, instead they would support the developing world by donations

Let us first have water for everybody and everywhere by developing water supply networks. No dry part on the land surface of the earth! Nature will take care of the rest. We are expanding more and more dry land surface by urbanization, deforestation and deserts formation causing climate change. Moisture content on the land surface of the earth controls the temperature and rain cycle. The more the land surface is moist, the cooler is the earth's surface and atmosphere and more rain cycle. We all know that.
So we can control Climate and present CC is reversible.

Details in devbahadurdongol.blogspot.com

devbahadurdongol.blogspot.com: 29.11.2014, 05:09

Water lowers temperature of hot objects - we feel cool, water extinguish fire, raining is cooling etc.

E-Ray: 05.11.2014, 04:49

My understanding is that 97% of the annual CO2 added to the atmosphere is natural, not man made. So if the CO2 increased since the industrial revolution from 280 ppm to 400 ppm, then the increase is 120 ppm. That means the man made contribution of 3% amounts to about 3.6 ppm added CO2. Are these 3.6 ppm really the cause of the IPCC's prediction of catastrophic global warming if humans don't dramatically reduce CO2 emissions from burning fossil fuels?

H.R.Prakash: 01.10.2014, 04:10

Dry heat is not difficult to bear but the humid climate after the rain is most uncomfortable. The impact of water vapor explains it.

George Carlin: 25.07.2014, 01:07

We’re so self-important. Everybody’s going to save something now. “Save the trees, save the bees, save the whales, save those snails.” And the greatest arrogance of all: save the planet. Save the planet, we don’t even know how to take care of ourselves yet. I’m tired of this rubbish. I’m tired of Earth Day. I’m tired of these self-righteous environmentalists, these white, bourgeois liberals who think the only thing wrong with this country is that there aren’t enough bicycle paths. People trying to make the world safe for Volvos. Besides, environmentalists don’t give a hoot about the planet. Not in the abstract they don’t. You know what they’re interested in? A clean place to live. Their own habitat. They’re worried that some day in the future they might be personally inconvenienced. Narrow, unenlightened self-interest doesn’t impress me.

The planet has been through a lot worse than us. Been through earthquakes, volcanoes, plate tectonics, continental drift, solar flares, sun spots, magnetic storms, the magnetic reversal of the poles … hundreds of thousands of years of bombardment by comets and asteroids and meteors, worldwide floods, tidal waves, worldwide fires, erosion, cosmic rays, recurring ice ages … And we think some plastic bags and some aluminum cans are going to make a difference? The planet isn’t going anywhere. WE are!

We’re going away. Pack your stuff, folks. We’re going away. And we won’t leave much of a trace, either. Maybe a little Styrofoam … The planet’ll be here and we’ll be long gone. Just another failed mutation. Just another closed-end biological mistake. An evolutionary cul-de-sac. The planet’ll shake us off like a bad case of fleas.

The planet will be here for a long, long, LONG time after we’re gone, and it will heal itself, it will cleanse itself, ’cause that’s what it does. It’s a self-correcting system. The air and the water will recover, the earth will be renewed. And if it’s true that plastic is not degradable, well, the planet will simply incorporate plastic into a new paradigm: the earth plus plastic. The earth doesn’t share our prejudice toward plastic. Plastic came out of the earth. The earth probably sees plastic as just another one of its children. Could be the only reason the earth allowed us to be spawned from it in the first place. It wanted plastic for itself. Didn’t know how to make it. Needed us. Could be the answer to our age-old egocentric philosophical question, “Why are we here?”


K. N. Owledge: 02.12.2013, 10:32

Hilarious! This "article" is so full of political baloney that you could feed Italy for years.

Water vapor absorbs infrared. Even the most basic of scientists understand this simple fact. When water vapor absorbs heat, the air around it is warmed, allowing it to absorb more water vapor, increasing the heat in the atmosphere. That's a certain positive feedback cycle.

It's amazing how the IPCC (Idiots Promoting Climate Catastrophe) will do back flips to link it all to CO2.

The reason they do this is simple . . . try and tax water vapor.

Eugen Kumicic: 02.07.2013, 21:55

if we all start driving hydrogen fuel cell cars won't that create massive amounts of extra vapor in the atmosphere and how do we deal with that? i don't think we can do anything if global warming is real.

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