Water Vapor Feedback

In most all of the climate models, the warming effect from feedback is actually much larger than the warming effect from CO2 alone.   That is why I have said for years that it is a waste of time to debate “greenhouse gas theory” as the real theory that matters to the proposition that climate sensitivity to CO2 is high is the theory that Earth’s temperature system is dominated by strong positive feedback.  And the largest feedback in climate models tends to be water vapor feedback, despite the fact that even the IPCC admits that such feedback is poorly understood.  To this end:

In a third paper, accepted for publication by the Journal of Theoretical and Applied Climatology, three scientists – two Australians and one American, revisit data on upper-atmospheric humidity. The three are Garth Paltridge, Albert Arking and Michael Pook, and they have found that, contrary to climate model predictions, water vapour in the upper atmosphere is acting as a brake on global warming.

Established climate models assume constant humidity at all levels in the atmosphere as the temperature rises. But, using data from weather balloons accumulated over 35 years, these researchers find this is not so. At the lower levels, it is higher than expected, dropping below normal at the higher altitudes.

This, they say, implies that “long-term water vapour feedback is negative – that it would reduce rather than amplify the response of the climate system to external forcing such as that from increasing atmospheric CO2.” This, in one fell swoop, challenges the central premise of the warmists that, once CO2 reaches a certain level, we experience runaway global warming.

  • Charles Higley

    Combined with Miskolczi and Zagoni’s work on the thermodynamics of CO2 and water vapor, this fairly well sums up the non-issue of CO2.

    Is it worthwhile to reprogram all of those supercomputers or would it be better to start with a PS-3 software engine?

  • An Inquirer

    From this short description, it is not clear to me how “higher than expected” water vapor levels in lower altitudes and “lower than normal” levels in higher altitudes would imply a negative feedback.

  • The idea of the wv feedback is basically that warmer air can hold more moisture (not that it does but that it can.

    This paper sparked some interesting discussion at climate audit:


    It seems that the major beef with the paper is that it uses reanalysis data to assess the trends and evidently this is considered somewhat dubious.

    I think that Lindzen has said that in clear sky the wv feedback is convincingly positive. If the wv feedback is negative it must, then, have something to do with shifting cloudiness.

    But personally I suspect that wv by itself is positive, although maybe not as strong as currently thought. The real key I suspect is in clouds. Spencer’s research is finding pretty strong negative feedbacks in the shortwave, implying that more reflection of sunlight occurs from clouds as the atmosphere warms.

  • Andres

    Andrew, your Lindzen comment is unreferenced and of dubious value. No one is talking about clear sky feedback in an instantaneous sense. The discussion is regarding changing concentrations of wv over time. This is an entirely different matter and is not related to clouds.

  • If you want a reference, it’s in this video:


    What you maybe aren’t getting is that if how wv behaves in impacted by cloud behavior-which would not be shocking, scientifically-then changes in the area of the planet where the sky is more or less cloudless will impact the strength of the wv feedback.

  • Laurent

    For those that are interested, the paper can be found at:

    Thanks for the head-up, this is important indeed!

  • gbaikie

    “…as the real theory that matters to the proposition that climate sensitivity to CO2 is high is the theory that Earth’s temperature system is dominated by strong positive feedback.”

    One could think of Earth as an ideal greenhouse. It lets sunlight in and prevents heat from escaping.
    Our moon is a contrast to Earth the ideal greenhouse. The moon’s day night cycle is about a month in duration. During the Moon’s night, the surface gets colder than anywhere on Earth {-153°C}. Even though the Earth’s polar region has longer nights than the Lunar night, they do not get as cold as the lunar nite- because of our “ideal greenhouse”. And in the lunar polar region in areas which never get sunlight, the surface temperature can get even colder than average nighttime temperature of -157 C [in the permanent shadow regions on the Moon it’s about -233°C].
    [Though it should be mentioned the way we measure temperature is different on the Moon than compared to how measure temperature on Earth- on Earth we measure the air temperature [5′ high in a white painted box] and on the moon it is the temperature of the top layer of the ground. But if you to measure the temperature of a dinner plate set on the ground on the moon and on the ground of earth’s polar regions, the plate would roughly have the above mentioned temperatures. But when it comes to discussing the differences in the warmer temperatures of earth and the Moon, this different way of measuring has a significant difference. For example on a typical day on earth with temperature reaching a high of say around 80 F- if you were instead measure temperature as you do on the Moon, the temperature instead of being 80 F, could be 180 F]

    Now, the hysteria concerning “global warming” [or new term, “climate change”] has to do with how hot earth could become. The story is humans make it a bit warmer and this results in a “runaway affect”.

    Now, science may inform us that this runaway effect has not occurred in the past and will not occur in the future. And perhaps one is even aware that what humans do is rather insignificant compared to what “nature” does. For instance, a super volcanic event in say the Antarctic could have a sudden effect upon sea levels. [And such volcanic events are not caused by “global warming” or “climate change”.]

    So even though a runaway effect would not happen, my question is what would happen to this planet, if it did. I am specifically excluding what kind reaction it will have on humans, because humans have and will react to minor events- mass insanity seems possible from a drop in a stock market for instance. So I wish to exclude the obvious political instability from consideration.
    Or a different way to pose this question:
    To what extent could earth become a more perfect greenhouse?

    Or we know we can increase average temperature due what is called urban heat island effect. What if that effect were increased by factor of million or billion more.

    For instance, we know that ocean area is warmer than land area- in terms of average temperature [or in terms of greenhouse effect]. By using something that is or mimics urban heat island effect and having vast land area covered, could the land area be made as warm [in terms of average temperature] or significantly warmer than ocean areas?

  • Stas Peterson

    This effect is predicted under Miskolczi’s theoretical work. Lower atmosphere wv decreases, to balance CO2 increases, are documented by Miskolczi. He uses it as confirmation of the ‘Saturated GHG’ thesis, for planets with an ocean.

  • TanGeng

    The observed effect is that high clouds, wv at high elevations is positive feedback. While wv at lower elevations are already in absorption saturation so any added vapor does nothing while cloud formation increases albedo. Low hanging clouds also trap heat below but that’s both because of the cloud and because it’s already warm and wet below.

    Secondly the lower clouds often form rain which gives off heat as it precipitates out of the air, and that is a huge heat conveyor belt from the surface into the middle of the atomsphere. When the precipitation occurs there a chance that the heat escapes out into space which is why high elevation water vapor is important, it traps that heat as it heading outwards into space. In order to see positive feedback, there should be a hot spot in the upper troposphere where both an increase in humidity and increased infrared absorption will cause a much higher increase in temperature there.

    That’s how the AGW theory goes at least.

  • Mark


    I thought the new term was
    Global Weirding. Keep up with the times there!

  • I have found the Bulletin of the American Meteorological Society increasingly polluted with climate simulation papers. Usually, somewhere towards the end of the paper, they quietly mention that they really don’t know how to deal with clouds (i.e. the model skill at forecasting cloud cover, cloud types, etc, is terrible).

  • An Inquirer

    TanGeng: Thank you. That was the explanation needed to make sense out of Meyer’s posting. However, the key step in your explanation is “wv at lower elevations are already in absorption saturation so any added vapor does nothing.” Are you sure about that claim? Do you have citations for that? — citations from both camps would be great.

  • Waldo

    ******”I have found the Bulletin of the American Meteorological Society increasingly polluted with climate simulation papers. Usually, somewhere towards the end of the paper, they quietly mention that they really don’t know how to deal with clouds (i.e. the model skill at forecasting cloud cover, cloud types, etc, is terrible).”

    Interesting. Could you give us an example?

  • An Inquirer

    I am not pursuing what John Moore has in mind. However, Waldo, if you asking in good faith, here is a reference from a pro-AGW source (a term that is used for convenience). On overhead #34 of http://meteora.ucsd.edu/~jnorris/presentations/Caltechweb.pdf

    Also, the IPCC has stated the problem with modeling cloud cover a number of times.

  • kuhnkat


    “Interesting. Could you give us an example?”

    Ask Gavin Schmidt over at RC how well his models do clouds. They are lousy with precipitation also.

  • Rob J Mitchell

    The question should be “Does evaporation cause warming?” because this is essentially what the climate models are claiming. Of course this is daft since a reaction that yields energy must yield energy if the reaction occurs. Ie if evaporation could cause warming then warming must occur if evaporation occurs. It wont wait 6 billion years!
    Of course evaporation causes both cooling and warming which creates a U-shaped buffer, and all buffering system are perfect examples of negative feedback.

  • Kelly

    Absurd images from recent National Dutch Climate Change PR-Event “Beat the Heat”.
    Meet the activists – simply too dim-witted and self-absorbed to realize what fools they are making of themselves..
    Meet the winners of the Climate Science Quiz [“What would the temperature of the earth be without the influence of G/house gases??”]..
    and watch someone being woken up.. by the subversive methods of an undercover skeptic..

  • Vesa

    TangGeng (among others) makes a very important point. The “rightists” talk about water only as a greenhouse gas. Water is, of course, much more than this. It is very unique in that it is the only gas in the atmosphere that can exist there in all three phases, i.e. gas, water and ice. In addition the the greenhouse effect, the following points about water are vitally important:
    – There are virtually limitless quantities of water available to equilibrate with air.
    – Water carries heat to the higher atmosphere and condenses there when it reaches the saturation point and suitable nuclei. This condensation releases a large amount of heat and water rains down to carry a new load.
    – Clouds, particularly as their upper surface often consists if ice, have a strong albedo effect.
    – Moist, warm air is carried also towards the poles with winds. If the temperature tends to increase on the equator, cloud formation towards the poles obviously increases. This could lead to a greater temperature gradient between the equator vs. the polar reagions. If we suppose such a gradient, it would also give power to sea currents and seawater mixing.
    I hope I have made myself clear enough as to why I think that water is a strong factor in keeping the atmosphere´s energy budget close to constant, provided that the incoming solar radiation is constant.
    The “rightists” seem to largely exclude these water effects from their calculations. Perhaps including them would make the models too unpredictable.

  • Vesa

    Since writing my previous post, I also tried to put a post on the discussion thread here: http://chriscolose.wordpress.com/2010/02/18/greenhouse-effect-revisited/ , where somebody purports to “scientifically prove” the greenhouse theory. In my post there I put the same arguments I presented here in my previous post. Sadly, and revealingly, they did not publish my post. Instead, they have chosen posts praising the article for publication. – Curiously, the basic assumption in that article is that the Earth is a hemisphere. Why not pancake.

  • I take back what I said in my previous post: There WAS a response to my post on the website I mentioned. You can check and evaluate it for yourself.

  • julie
  • i like it very much !!!