A Window on Water Vapor and Planetary Temperature

Here is some interesting news; according to data from NOAA’s Earth System Laboratory, atmospheric water vapor is on the decline globally.

You’ve probably heard many times how water vapor is actually the  most important “greenhouse gas” for keeping our planet warm, with an effectiveness far greater than that of CO2.

It is generally accepted that the rank of important greenhouse gases is:

  • water vapor and clouds which causes up to 70% of the greenhouse effect on Earth.
  • carbon dioxide, which causes 9–26%
  • methane, which causes 4–9%
  • ozone, which causes 3–7%

Note the range of uncertainties, on water vapor some say the percentage goes up to 90% with reduced numbers on the other three.

It is absolutely true that water vapor is the gas most responsible for the “greenhouse effect” of our atmosphere. Greenhouse gases let short-wave solar radiation through the atmosphere, but impede the escape of long-wave radiation from the Earth’s surface. This process keeps the planet at a livable temperature: Without a suitably balanced mixture of water vapor, CO2, methane, and other gases in the atmosphere, Earth’s average surface temperature would be somewhere between -9 and -34 degrees Fahrenheit, rather than the balmy average 59 degrees it is today.

This graph then from NOAA’s Earth System Research Laboratory, showing specific humidity of the atmosphere up to the 300 millibar pressure level (about 8 miles altitude) is interesting for it’s trend:


Click for original source of the graph

[UPDATE2: After reading comments from our always sharp readers, and collaborating with three other meteorologists on the graph, I’m of the opinion now that this graph from ESRL, while labeled as “up to 300mb only” is misleading due to that label. The first impression I had would be from the surface to 300mb i.e. the “up” portion of the label, but on the second thought I believed the label was intended to be numerical meaning “zero to 300mb” or from the top of the atmosphere down as opposed from the surface up as we normally think of it. The values looked like anomaly values, but are inthe range of absolutes for that elevation also.

Thanks to some work by commenter Ken Gregory, looking at other ways this and similar graphs can be generated from the site, it has be come clear that this is a level, not a range from a level. The label ESRL placed “up to 300mB was intended to list the availability of all data levels. Thus there is no 200mb data.

This demonstrates the importance of labeling a graph, as without any supplementary description, it can be viewed differently than the authors intend. A better label would be “at 300mb” which would be unambiguous. ESRL should correct this to prevent others from falling into this trap.]

For some background into atmospheric absorption efficiency of the electromagnetic spectrum, this graph is valuable:

Note the CO2 peak at 15 microns is the only significant one, as the 2.7 and 4.3 micron CO2 peaks have little energy to absorb in that portion of the spectrum.  But the H2O (water vapor) has many peaks from .8 to 8 microns, two that are fairly broad,  and H2O begins absorbing almost continuously from 10 microns on up, making it overwhelmingly the major “greenhouse gas”.

Here is another graph looking at it in a different way:


Click for a larger image

Note that water vapor plays quite a role in keeping the planet cool by absorbing some percentage of incoming radiant energy.

The yellow line is what we’d get without an atmosphere, and the blue  line what we get with it. Sunlit temperatures on the earth’s surface are substantially less than those on the moon (up to 123°C) because our atmosphere intercepts some incoming solar short-wave radiation as well as some outgoing long-wave infrared.

So when we see atmospheric water vapor dropping as shown in the NOAA ESRL graph above, you know it has to have an effect on our overall planetary energy budget, the question that will be argued is; “how much”?

h/t: Thanks to atmospheric physicist Jim Peden,  and also to Barry Hearn, and Alan Siddons for some of the graphs and background to this post.

UPDATE: See part2 of this post here

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117 thoughts on “A Window on Water Vapor and Planetary Temperature

  1. Thanks Anthony,

    I’ve been looking for this data for a long time. If possible can we see other levels of the atmosphere.

    Generally, this is another area where the models are wrong as the assumption is that specific humidity remains constant. And this is a key assumption to the sensitivity estimates for GHGs.

    It seems the models are getting too many specific assumptions/outputs wrong such as tropical troposphere, Antarctic, and temperature trends, in general, to be reliable.

  2. Doesn’t decreased water vapour fly in the face of positive feedback in global warming theory.

    I seem to recall that the worry from increased CO2 is that it causes positive feedback of increased water vapour, and therefore could cause run away global warming.

    This seems to contradict that as CO2 levels continue to rise and now water vapour levels are decreasing.

  3. Greenhouse gases let short-wave solar radiation through the atmosphere, but impede the escape of long-wave radiation from the Earth’s surface.

    Sunlit temperatures on the earth’s surface are substantially less than those on the moon (up to 123°C) because our atmosphere intercepts incoming solar short-wave radiation as well as outgoing long-wave infrared.

    I must be missing something because in the beginning you said greenhouse gases let through short-wave, and then later said they intercept short-wave.

    On one hand they warm the planet (pass through solar short-wave and absorb earth-radiated long-wave), and on the other they cool the planet (intercepts incoming solar short-wave).

    You’ll have to clear that up for me.

    REPLY: The let in some, they intercept some. Its two way partial mirror, otherwise we’d never see stars or stay warm

  4. raypierre @ realclimate talked about anthropogenic GHG’s and strong water vapour feedback in 2005

    The authors then subtract off the part of the downward infrared radiation increase attributable to temperature and water vapor increase, and thus estimate the part due directly (as opposed to via feedbacks) to the increase in anthropogenic greenhouse gases such as CO2. They estimate this to be about one third of a Watt per square meter. This is not in bad agreement with estimates from detailed radiation models run by the authors, which say that the change in surface radiation due to the 12ppm CO2 increase between 1995 and 2002 should be about one fourth of a Watt per square meter. It is striking that the changes in the Earth’s surface radiation budget due to anthropogenic greenhouse gases are so profound that they can be directly observed on a regional scale, over such a short time period. So far, so good. Physics seems to be working as it should, and climate scientists seem to be basing their understanding of climate change on rock-solid physical principles….I’m wondering if there needs to be some rethinking on this.

  5. Very interesting. I have a related question. Anthony explained the greenhouse gas very well. If GHGs absorb long wave radiation reflected back toward space, isn’t there a diminshing return as GHG concentrations increase? Think of it this way, I have a window film that blocks 50% of the light. The first sheet I put on the window reduces the visible light by 50%. The next sheet only 25% (50% of 50%), the third 12.5%, the fourth 6.25% and so on.

    If that analogy is right, we would expect that the first 100ppm of CO2 to produce the MOST warming. Is there something wrong with my reasoning? At some point adding more GHGs will have almost no effect on the energy absorbed.

    REPLY: Your reasoning is spot on, CO2’s effectiveness as long-wave reflector with concentration is logarithmic

  6. That graph is for the global average. It seems that regional patterns would be important to know before drawing conclusions.

  7. Its probably not reasonable to expect the models to match short-term trends. They are not built that way.

    We now have roughly 30 years of satellite data though, but I mostly see matches to Hadley or GISS “adjusted” data. The matches there appear to be reasonable for some model runs (the ones that assume CO2 reduction or stasis).

    My trust of GISS is somewhat compromised (can’t image why) and MSU data has its own problems, but these pale compared with the surface station problems.

    So who is working with MSU data to calibrate their models?

  8. I haven’t looked into this too deeply, but I can’t help noticing that the water vapor graph looks somewhat like the sunspot graphs that we’ve seen. If there was some sort of correlation of sunspots to water vapor that might go a long ways in explaining why a low amount of sunspots or a quiet solar cycle seems to create mini ice-ages.

    This is just off the top of my head, so don’t flame me if it actually sounds silly. Just thought I’d put it out there.

  9. “Your reasoning is spot on, CO2’s effectiveness as long-wave reflector with concentration is logarithmic”

    As would water vapor, right?

    “That graph is for the global average. It seems that regional patterns would be important to know before drawing conclusions.”

    Why would regional patterns matter when we’re talking about GLOBAL warming?

  10. This is an amazing assertion by NOAA…. And based on past manipulations by NASA/NOAA, I find it VERY suspect and stinks like a hog farm. For openers, why did NOAA wait so long before announcing the drop in humidity? According to the above chart, the big drop began around 1958.

    For the past year, I’ve spent hundreds of hours pouring over research papers on the various forms of water (solid, liquid, and vapor) in our atmosphere for an article on “The Mysterious Climate Project.” Quite frankly, each time I think I have a handle on it along comes another research paper or scientist with still another figure. The above article states water vapor and clouds cause up to 70% of the greenhouse effect on earth. Before I go on, blog members should realize the “volume” and the “effect” are two different animals! You can have all the volume you want (Argon for example), but if it has little or no effect it’s immaterial.

    During the course of my research, I’ve received dozens of papers and letters from well known atmospheric physicists and climatologists who believe the “effect” figure should be closer to 95%. So how does this square with the above? I don’t know. Are some of my figures already outdated? Possibly. The truth of the matter seems to be that climatology is such an infant science, we essentially know VERY little of the subject. For the simplistic Pogies to run around like a bunch of chickens with their heads cut off screaming the sky is falling, simply shows how intellectually challenged they really are.

    As the Pogies continue witnessing their AGW claims go up as so much smoke, it appears they are embarking on a crusade of minimizing every other variable associated with the climate in order to make CO2 look more important than it is.

    If I were young and just entering college, my major would be atmospheric physics. It is virgin, it is challenging, it is intriguing, and it is the wild wild west all over again! To me, atmospheric physics and its associated fields remind me of that knock ’em dead, good looking redhead with a tight butt and a sexy swish in her walk! Okay, okay, maybe not that much, but close to it!

    Jack Koenig, Editor
    The Mysterious Climate Project
    http://www.climateclinic.com

    REPLY: There was no “announcement” per se, this was a data plot from the ESRL website that became self evident from the recently released data and upgraded web site that allowed such examinations by members of the public.

  11. Henrik Svensmark has written extensively on the relationship between the sun’s magnetic field and cloud formation; unfortunately, I’m out the door for an appointment and can’t post any links now.

  12. How can this be? Burning all that gas, oil and coal which makes the evil CO2 that warms the Earth also produces vast amounts of water vapor. So it can’t decrease.

    Unless human activities aren’t such a big deal.

    Blasphemy!

    A bit more OT: It looks like we are close to saturation on inbound absorbtion (for CO2). How close to 100% are we on outbound radiation? Shouldn’t be much at near IR, what about the 15u stuff?

  13. This is a Question.

    If we assume (I hate that word always gets me in trouble) that water vapor is at 1000 ppm and that it falls by 50% to 500 ppm the current thought that it causes warming then the warming caused by water vapor would decrease by 12.5% causing lower water vapor content as cooler air tends to be drier. then the air could lose another 50% down to 250ppm and this could cause an additional 25% cooling causing another reduction of temp causing the air to condensate reducing water vapor again if another 50% we lose an additional 50% ability to warm and so forth. I wonder if the modelers put this in their computations. I know that the figures I am using are not correct but just food for thought. It would seem that with the sun possibly having influence on water vapor our problem might be run away cooling not runaway warming. (Ice ages again) I know that my figures are exaggerated but If Gore can as truth why can’t I in a question while admitting that they are exaggerated?

    Come on Sun

    Bill Derryberry

  14. Ok, GHGs let through some short-wave (visible and very-near infra) and absorb others. They keep in/out the strong majority of the infrared bands, and H2O keeps in/out just about all the microwave range stuff.

    Cool, I guess I just got confused on terminology. Blocking a small portion of the short-wave stuff doesn’t sound like it does much “cooling”. Maybe it just doesn’t warm as much as it might, which I guess is pretty much the same thing as having a cooling effect.

    Would you happen to have any charts that show the bands of radiation that the Earth puts out? Does Earth radiate infrared pretty uniformly across wavelengths, or does it radiate in particular wavelengths?

    I could see a significant difference in effects if Earth happens to primarily radiate at the 6 micron wavelength of infrared where H2O is the only thing that really keeps that in, compared to if Earth radiates more at 4 microns where it’s primarily CO2 that keeps the radiation in.

    Or Earth may radiate in a smooth grade of wavelengths, and we can do relatively easy average-calculation of what effect the dropping H2O might have on keeping in infrared radiation.

  15. Anthony, you say “Without a suitably balanced mixture of water vapor, CO2, methane, and other gases in the atmosphere, Earth’s average surface temperature would be somewhere between -9 and -34 degrees Fahrenheit, rather than the balmy average 59 degrees it is today.”

    Actually, in his book Roy Spencer has recently reminded people of a paper from 1964 by Manabe and Stickler, where they calculated the surface temperature with major greenhouse gases and natural convection at about 140 F. The lapse rate is also almost double what is actually observed. It is the resulting weather that accelerates the transport of heat from the surface to the top of atmosphere, reduces the lapse rate to the observed values of about 6.5 K/km, and regulates the surface temperature at around 59 degrees F. It is a subtle difference, but shows that weather processes are a huge stabilizing feedback mechanism to the global climate. You don’t need much of a change in cloud cover or precipitation efficiency to have a dramatic impact on surface temperature.

    REPLY: Correct, weather is part of the global heat transfer mechanism, hurricanes and thunderstorms do quite a bit of this transport.

  16. Pardon me, I do not understand, what the globally averaged relative humidity really means. E.g.; values of order 0.2 and somewhat less imply clear sky situations all year long. Or try to estimate the latent heat content in the atmosphere from these numbers, by using globally averaged mean temperatures. You probably get enormous fluctuations which do not make any sense. Humidity saturation increases exponentially with temperature. How meaningful is it to just take the average over exponential functions? Finally, it is the absolute humidity which determines any water vapor greenhouse effect. It is also the absolute humidity, which determines the amount of latent heat, transported into the upper troposphere by convection and which, according to R.S. Lindzen may more or less bypass the blocking of radiation cooling by the greenhouse gases.

  17. Anthony — I believe you are wrong on the primary reason for higher peak temperatures on the moon. While the earth’s atmosphere (clear sky) absorbs about a quarter of incoming solar radiation before it hits the surface (~1365 W/m^2 at the top of the atmosphere, ~1000 W/m^2 at the surface), remember that this energy is still absorbed in the earth “system”.

    Remember that the moon’s day/night cycle is a month long in earth terms, so its “daylight period” is two weeks long. This gives plenty of time to get the surface cooking. Think of how hot the earth’s surface would get in the afternoon of a month-long day.

    Time-averaged, the moon is cooler than the earth, one of the key pieces of evidence saying there is a natural greenhouse effect on earth.

    REPLY: Excellent point, one which I hadn’t considered. That duty cycle does indeed change the issue.

  18. This is very interesting. As the basic CO2 incriminator is the feedback mechanism between water vapor and temperature rise this is another nail on the coffin of anthropogenic CO2. One does not need a sophisticated analysis to disprove a correlation with the monotonic CO2 rise of the last decades.

    It is amazing that they were sitting on such data and never checked their feedback hypothesis.

    Thanks for finding it for us.

  19. Anthony,

    Do you have a link for the original data for this? I’ve found lots of huge gridded datasets, but nothing as simple as this annual/monthly global mean.

    Thanks

    Paul

    REPLY: This is from web plotting automation similar to yours, I’ll see if I can backtrack the raw data.

  20. Anthony et al, if water vapor is dropping it’s effect should first be felt in the tropics. Do we have cooling there?

    Secondly, dropping water vapor is a sign of cooling somewhere, oceans, troposphere, polar regions, temperate regions. So where do we have cooling? We think we have cooling in the seas and the troposphere, South pole any other areas? Perhaps they are enough.

  21. Here is a nice chart on the W/M^2 of sunlight: http://www.spacewx.com/solar_spectrum.html

    Notice that most of the energy contained in sunlight is in the 1,000 (10^3) to 10,000 (10^4) nm range (1 to 10 mircon respectively). Where is CO2’s range???? two small isolated peaks below 10 mircons and one larger above 10 microns. And where is the H20 range??? Spanning most of the range of sunlight. That in itself should negate the silly argument about CO2 absorption and emission driving H20. It’s just plain deceptive to even maintain the position.

    For those of you math challenged, here is a nm to mircon calculator: http://www.unitconversion.org/length/nanometers-to-microns-conversion.html

  22. GHG alarmists obsess about positive feedbacks. They obsess about positive feedbacks that don’t exist. The ones that do exist generally result in several thousand feet of continental ice covering half of North America.

  23. Locri — yes that was my thought as well. However after looking around for some time, and reviewing papers about what Svensmark has proved, I get this — When you take into account the Svensmark cosmic ray effect then a possible theory begins to come to the fore. Could it be that sunspots are just an indicator, not the prime mover for cooling, the real player might be cosmic rays and low level cloud formation and subsequentially higher precipitation.

    Sunspot number would likely be the prime forcing for warming, because of the direct radiative effect of CMEs and increases in the solar wind. So just having sunspot numbers go down, like in a normal solar minimum, may not provide enough forcing for cooling. Consider, there have been periods of low sunspot activity without any cooling correlation before, a normal sunspot minimum for instance.

    What we have here is the unique observed event of the lowered sun’s magnetic component.

    Try this line of reasoning — The sun goes quite, caused primarily due to a drop in the sun’s magnetic field, increasing the incidence of cosmic rays on Earth’s atmosphere, this in turn increases low level clouds, which produces more rain, which then cools Earth. The missing link was the cosmic rays and cloud formation theory which was provided by Svensmark..

  24. Anthony – the decrease in specific humidity at ~6 miles (300mBars) is very interesting and the site you linked to is pretty neat. However, before jumping to too many conclusion re: feedback etc., you might want to check the trends in specific humidity at lower atmospheric levels. 600 -900 mbars seem pretty flat, but 950 mbars, and particularly 1000 mbars show very clear increasing trends over the time period in question. From eyeballing the g/Kg numbers, it appears that the lower troposphere is gaining more water than the upper troposphere is losing. That’s just eyeballing it though, and maybe it balances out. Keep up the good work.

    BobN

    REPLY: As I understand this data, this is data up to 300 mb, not at 300 mb. I’ll dig a little deeper though to be sure.

  25. What we need is a graph showing heat capacity in watts/ppm at given temperatures and heat absorption rate of change in watts/ppm.

    Water vapor absolutely dwarfs CO2.

    Water is also a working fluid for heat transfer from the Earth’s land and ocean into space. When it condenses from water vapor into clouds, it releases huge amounts of heat. The reverse is true when fog or clouds dissapate.

    Everyone is familiar with a cold can of soda having water condense on it on hot humid days, thus warming the can. Then there is the nighttime convergence of dewpoint and air temps which prevents nights from getting cold.

    CO2 does not do this.

  26. Oh oh… the drop in water vapor can’t be a good omen. Ice age water vapor was very low… could we be heading towards another Maunder or Dalton Minima?

  27. So, how long will it be before the US Supreme Court declares water (in vapor form) a pollutant?

    So much for hydrogen fuel alternatives.

  28. I see where you’re trying to take this argument, but I have a few comments.

    The major assumption going in here is a syllogism – that specific humidity (which, as a reminder for those of you who don’t know, is simply the ratio of water vapor to dry air in a parcel) is directly proportional to temperature which is logarithmically proportional to CO2 concentration. I won’t fault the logical argument, but I will point out something that I think contradicts this notion:

    Extending this argument one step further, higher specific humidity equals a higher amount of precipitation dispensed from the atmosphere. However, this is not a prediction of global warming – climate models have no consensus on what the global precipitation change will be, although there is some consensus on certain regional effects. To illustrate this, look at 1998 on the first graph; why does the warmest year on record not have the highest average specific humidity?

    In reality, the water vapor feedback is much more complicated than being acknowledged here. As has been already brought up, water vapor varies dramatically by region and time. It has an extremely short residence time in the atmosphere compared to CO2.

    You hypothesize that decreased water vapor means less energy reflected away from the atmospheric system and subsequent warming. Then why is an apparent decrease in average water vapor correlating, as skeptics point out at every chance right now, to a decrease in global temperature rather than an increase?

    REPLY: ?? Your last question: It is explained clearly in the article. Note this is up to 300mb so while there may have been an increase in near surface humidity in 1998, it was likely manifested mostly at lower levels of the atmosphere.

  29. Wow! Anthony if graphs can provide food for thought you just gave us a 6 course meal. That graph on electromagnetic absorption is one I’ve been looking for. (I would also like to have the original source for that if possible.) But if I’m reading it right it says in the wavelengths that water or CO2 can absorb, they are already absorbing nearly 100%. So adding more would not make much difference.

    And the graph showing water vapor content is also very surprising. The decreasing trend from 1960 to 1975 more or less agrees with temperature drops during that time. But the drop from 1990 to 2000 runs counter to the temperature trend. It sure seems that increasing temperatures would cause more evaporation but the graph from 1990 to 2000 shows the opposite.
    Wow- Lots to think about.

  30. Well, how can the realclimate boys claim a positive feedback from increase in CO2 to increase in H2O vapour? It is obviously non-existance.

    [snip]

  31. Anthony,

    So this chart has been available all along, for those who cared to look??

    So much for due diligence on the part of the model makers when they “assumed” that CO2 induced warming was causing the atmosphere to hold more water vapor.

  32. Anthony – I am pretty sure the graphs are for the specific humidity at that atmospheric level and the reason it is listed as up to 300 mbars is because they don’t have data for higher atmospheric levels. If you check the plot of specific humidity at 1000 mbar,e.g., you get values of around 7.7 g/kg, at 925 mbars, listed values are around 5.9 g/kg, while at 300 mbars, the values are around 0.2 g/kg. Obviously, this decrease in value with height makes sense since the atmosphere can’t hold as much water vapor at higher altitudes.

    I did a quick download of the data for each listed level (1000, 925, 850….300) and summed the annual average values (I do not know if this is the right way to do this analysis! since I am not a meteorologist). What it showed was a modest increase (~2.5%) in the total specific humidity from about 23.4 g/kg to about 24 g/kg for the summed values from 1000 to 300 mbar for the period from 1950 to 2007. I have the data file and a graph but do not have anyway of posting it on the site.

    BobN

    REPLY: Bob check your email, I’m interested in determining if this data plot from ESRL is “at level” or “up to” as they state. The values you cite are right for levels, but I viewed this as an anomaly plot for up to 300mb rather than absolute values for that level.

    But the question needs to be settled, I may be in the wrong as to my interpretation.

  33. MattN (07:33:48) ,

    Here is my understanding of why regional differences matter to the climate:

    Regional patterns matter because physical processes take place at the temperature, pressure, humidity, etc. at the location they are happening. They do not take place based on the average temperature of the earth or any other averages.

    Having more or less water vapor on average is useful for tracking trends but not for determining what physical processes are taking place in a certain region.

    For instance if cold dry air comes out from high latitude (a cold front) and causes water to be removed from the warmer, more humid air over a warm part of the ocean, more radiation will escape into space from that area of the ocean than from another area of the ocean that still has humid air above it (assuming the ocean temperature is the same in both regions). This is called weather and may not affect the average water vapor in the air if water is evaporating elsewhere and replacing the water vapor that has rained out, but it is important to the radiation budget of the earth.

    If the average is done properly (i.e. perhaps a geometric average is necessary for the particular physics of a process — just an example), then the trend can give us some clues about what is happening overall. For instance, if CO2 continues its increasing trend but water vapor continues its decreasing trend we can conclude (assuming all other things are equal, which is the catch) that an increase in CO2 does not induce an increase in water vapor in the atmosphere.

    Lyman Horne

  34. Well, so much for one of the pillars of positive feedbacks in AGW. As I recall the IPCC treatment of feedbacks in FAR claims a huge amount of ‘warming’ influence from increased water vapor caused by increased CO2 warming. If this is not the case, then the IPCC calculations are in deep trouble.

    It does fit with NOAA data that shows an increase in precipitation in the US since 1900 though.

    There is one aspect of this that bears scrutiny. IF water vapor is decreasing and water vapor is overlapping a a goodly portion of the CO2 absorption band, then wouldn’t this allow CO2 to absorb more long wave radiation? This would be only true if the remaining water vapor did not still absorb all the radiation available at those wavelengths.

    Let’s see here:

    IPCC can’t calculate the sensitivity of the climate to CO2 (nobody really can) and may have overstated it by a factor of 3-4.

    Water vapor is not providing a positive feedback
    Aerosols are not providing a ‘dampening’ of the warming.

    Overall not looking good for the AGW crowd.

  35. CoRev-

    Yes, temperatures in the tropics are currently at their lowest levels since 1989…with anomalies lower than any other region on earth.

  36. Doesn’t decreased water vapour fly in the face of positive feedback in global warming theory.

    Yes.

    And now we know why the AquaSat data is being swept under the carpet:

    Not only less vapor (cooling via less GHG), but more low-level cloud cover (increased albedo).

    So much for positive feedback.

  37. Can someone with more knowledgable put some perspective to the increments in specific humidity on the left side of the graph? The graph shows flucuations from a high of just over 0.21 to a low of about 0.172 over the course of 60 years. How significant is that?

  38. Austin- you say “CO2 does not do this.”

    Actually, there may be a place on Earth where CO2 can condense to its solid phase during cooling and sublimate during subsequent warming. But I don’t know how often Amundsen Station in the Antarctic has dipped below -78.5 C!
    : )

  39. OOPS. Well maybe I was to hasty in assuming that less water in the air means there was less evaporation. Of course that is one possibility but it is also possible that there has been more precipitation, which drains moisture from the air.

    BTW does anyone know if molecules in the atmosphere can gain enough energy to escape the earth’s gravity? That would provide another means by which energy could leave the earth, besides radiation.

  40. Counters:
    “As has been already brought up, water vapor varies dramatically by region and time. It has an extremely short residence time in the atmosphere compared to CO2”

    I fail to see what relevance of residence time to what is an on-going process. So one particular molecule of H2O may not stay in the atmosphere for long, but it’s the total concentration at any point in time that has any effect.
    Besides, the concentration of CO2 also varies quite widely by region and time. The diurnal range over woodlands can be in excess of 100ppm.

  41. The new humidity data causes me to wonder if there is a correlation between it and the period of time that atmospheric CO2 is retained. As I understand it, the GCMs assume that CO2 is retained in the atmosphere for about 100 years. This assumption supports the hypothesis that CO2 and water vapor interact so that an exponential increase in temperatures occurs as a result from prolonged long wave retention in increasing amounts.

    Conversely, 50 years worth of empirical research indicates that retention is between 4 and 12 years. Does the new data falsify the GCM assumption about the length of the cycle for retention of CO2?

    Am I missing something? I look forward to reading new comments on this thread.

  42. Just noting that Global Warming theory relies on the assumption that “Relative Humidity” would remain constant (the amount of water vapour the atmosphere can hold given the temperature – as relative Humidity approaches 100%, it rains).

    In Global Warming theory, as atmospheric temperature increases, the amount of water vapour the atmosphere can and does hold will increase although the Relative Humidity would remain constant.

    Anthony’s chart relates to “Specific Humidity” which is the actual mass of water vapour in the air. Specific Humidity should be increasing according to Global Warming as the warmer air is able to hold more water vapour.

    So not only is Specific Humidity not increasing with the supposed increase in atmospheric temperature, it is actually falling (which is the nail in the coffin for the +3.5C increase in temperatures for a doubling of CO2 sensitivity estimate.)

  43. Pingback: Water Vapor and Planetary Temperature « A1A South

  44. Anthony,

    At 8 miles up, isn’t that in the upper troposhere, above the height where most of the water vapor in the atmosphere is? In fact, according to the RSS data, that’s up in the TTS (very slight warming) and TLS (very distinct cooling) temperature bands as measured by the satelites. So if temps are cooling that high up, you’d expect to see water vapor decrease.

    Another question. What is the data collection method behind that graph? Given that the trends start in 1940s, I’m guessing radiosondes. There have been bigger discrepencies in the radiosondes with changing instruments, changing locations, time of day, etc… then there have been with the surface temperature stations. You should look into that.

    Also, CO2 becomes more important at higher attitudes, because it’s well mixed throughout the atmosphere, unlike water vapor, which is more important near the surface. So increasing the amount of CO2 is going to block more outgoing longwave radiation higher up in the atmosphere, which is going to have an impact on the radiation budget. The planet is going to have to warm up to equalize the amount of radiation received.

  45. Ken,

    “At 8 miles up, isn’t that in the upper troposhere”, but it says “up to” 300mb not “at” 300mb.

    Can we assume they are measuring the “specific humidity” from sea level up to 8 miles as an average?

  46. Mr Watt,

    From your link: …&level=300…. That’s in the stratosphere, which is cooling.

    Go to here: http://www.cdc.noaa.gov/cgi-bin/Timeseries/timeseries1.pl
    try it again at say 1000mb height.

    Then you get specific humidity going up.

    It helps to look in the troposphere (where there’s warming) rather than at 300mb in the stratosphere. Yes the dataset goes up to 300mb, but you selected 300mb as the analysis level.

  47. Dave,

    “Can we assume they are measuring the “specific humidity” from sea level up to 8 miles as an average?”

    I don’t know what we can presume from that graph, which is why I asked the question. The graph Anthony presents isn’t consistent with the results from peer reviewed science. Take a look at these three articles:

    Water Vapor Feedback is Rapidly Warming Europe

    http://www.agu.org/sci_soc/prrl/prrl0538.html

    Trends and variability in column-integrated atmospheric water vapor

    http://www.springerlink.com/content/v164l177374p1445/

    Enhanced positive water vapor feedback associated with tropical deep convection : new evidence from Aura MLS

    http://trs-new.jpl.nasa.gov/dspace/handle/2014/40309?mode=simple

    Water vapor feedback is clearly increasing, and in some cases, much more than predicted by models.

    Anthony has used incorrect methods before (his comparison of the anomalies of the different surface and satellite temperature datasets without first putting them on a common baseline for example). I think we should know what his methods are and how he derived this graph before we jump to conclusions.

    Ken

  48. Ken,

    Look at the date on the American Geophysical Union article. It’s dated 2005 and it says that it looks at data from 1995 to 2002.

    The Beacon eSpace article talks about “Recent simultaneous observations of upper tropospheric”

    “derived this graph before we jump to conclusions”….I could be wrong but I think the graph is from NOAA

  49. Anthony,
    Great, was lookin’ for that data for quite some time.
    By the way, I use in a spreadsheet the data (global, ocean, temperature anomaly) from:
    http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt
    versus the Pacific warm water volume from:
    http://www.pmel.noaa.gov/tao/elnino/wwv/data/ (wwv.dat)
    – I am using this one, because global ARGOS datas have still too less years to be valuable –

    Interesting – especially – is the year 1997/1998, when the Pacific – lost or
    supplied to atmosphere – around 24% of its warm water volume.

  50. “Up to 300 mb” may be referring from 0 mb to 300 mb, which would equate to ~6 miles on out to space.

  51. Anthony,
    addendum to my 18-06-2008 14:24:29,
    as far as know, the heat capacity of – oceanic – water versus atmosphere, is
    more than 3000:1 (if I am wrong, please, I should be corrected).
    So the year of ’98 – with it’s temperatures – is caused by the oceans switching
    from collecting of heat energy to emitting heat energy, until it fell to it’s lower
    threshold, causing the not so warm ’01/’02 temperatures, because after several
    months of emmiting heat energy, the fallback to collection of heat energy – re-occured.
    I couldn’t say, it’s reasoned end-to-end from my side, I simply stumbled over it.

  52. ‘Up to 300mb’ I think means from 0 mb up to 300 mb. Not from the surface up to where the pressure is 300.

  53. I am beginning to see several nested loops here:

    Water vapor balance is driven by two primary factors: evaporative input and precipitated output.

    Solar output affects evaporative input by heating exposed water and heating surfaces containing pore water, driving osmotic evaporative surface drying.

    Solar output reduction therefore directly reduces evaporative inputs, by reducing surface heating.

    If the cosmic ray cloud-seeding hypothesis is correct then reduced solar output, also increases ionized condensation nuclei. That increases low clouds, increasing albedo, which further reduces heating and lowers evaporative input further.

    Increased condensation, with lower surface temperatures, means that the a larger proportion of precipitated condensate does not return to the vapor load in the atmosphere but to surface water and pore water.

    This means the coincidence of several negative vapor balance factors.

    Seas are rising, which might be in part explained by additions of net unvaporized precipitate, as well as, or perhaps better than the volumetric thermal change (which heating isn’t happening anyway, at least not in the upper 700 m).

    Sea levels are rising (less than the GCM’s predict) so that may actually be a vapor volume loss signal (they mostly hold water vapor constant, and therefore would naturally misinterpret that as heating signal, an artifact of that bad assumption on a basic gas law issue).

    Seems an easy thing for a basic correlation analysis:

    What is the comparison of the balance of the mass of water in the reliably observed sea level rise data to the mass of lost vapor represented in the declining specific humidity?

  54. Anthony:

    Good thought provoking stuff.

    Is it possible that what you are talking about is the reduced evaporation rate that has been recorded worldwide (albeit at the surface). This is a well known effect and was noted in Australia initially and is probably caused by increased atmospheric particulate pollution. There are mountains of data on this.

    It is interesting that global warming would be probably worse if this effect was not present. By the way evaporation rates are measured worldwide by farmers interested in soil moisture for planting and there is a fairly good data record going back quite a way. Also, if I remember correctly evaporation is as dependant on the “photon density” impinging on the water as ambient temperature. Hence a smoky atmosphere slows evaporation even with no ambient temperature change. – But now I am stretching my memory so I need to check.

  55. I cant help thinking that the Earths temperature would significantly influence humidity. Lower temperatures mean less evaopration and what water vapour is in the atmosphere will in fact more readily form clouds at lower temperatures.

    Naturaly air pressure would influence this formation.

    In fact their may be an interesting investigation in whether temperature could be measured from global humidity information.

    I would also like to see what the links between humidity and relative cloud cover at different altitudes are.

  56. David Segesta wrote: “OK now I’m confused. This graph has all the same labels but shows a completely different graph.”

    Actually David, the Spicific Humidity scale on the left side is quite different than that on the original graph. Other than that, it looks like a typical NASA adjusted graph.

    Jack Koenig, Editor
    The Mysterious Climate Project
    http://www.climateclinic.com

  57. Some very rough figures:

    Greenhouse effect = 30 degrees Celsius.
    Water = 70% of 30 degrees = 21 degrees.
    Reduction in water vapour content from graph = 10% (from about 0.2 to 0.18)
    Predicted reduction in temperature based on water vapour greenhouse effect from graph = 2.1 degrees.
    Either my logic is off, or that graph is wrong, or the temperature has cooled a huge amount since 1990 without being detected by our thermometers. Or something else has caused a 2 degree warming at the same time to compensate.

  58. De-lurking for a quick comment to clear up apparent confusion on the meaning of the specific humidity graph data.

    Looking at the inputs to the graph, there are two main ones: the actual variable to be plotted, and the “analysis level”.

    The variable you are plotting is “Specific humidity (up to 300mb only)”, but you are plotting the 300mb analysis level. If you were to try to plot the 250mb level, you’ll find that you get an error page stating that there is no data for that level.

    In other words, the “up to 300mb only” means that the data cuts out at that pressure/height – there is no data for any altitude with lower pressure levels. But when you choose an “analysis level” you are plotting the level at that specific level, not a cumulative level.

    Gabriel

  59. The subject of trends in atmospheric water vapour is critical to the whole climate debate. If you dig around you will find that real work is being done in this area of study.

    A reference that might be useful in this discussion is:

    Mieruch, S et al 2007. Analysis of global water vapour trends from satellite measurements in the visible spectral range. Atmospheric Chemistry and Physics Discussions 7: 11761-11796.

    Then have a dig around in the references they cite.

    Cheers

    Rob R

  60. Syl (Lutnes) (15:13:58 ) : I think the original plot is at 300mb

    I went back and replotted the data and noticed that when you choose different ranges, you get different results

    300mb – 300mb shows a downward trend for last half 20 century
    400mb – 300mb shows a downward trend for last half 20 century
    500mb – 300mb starting to flatten
    600mb – 300mb flat trend
    700mb – 300mb flat trend
    850mb – 300mb flat trend
    925mb – 300mb flat trend upward trend around 95 on
    1000mb – 300mb downward trend ’til 70’s then upward trend on

    IMO, what it really shows is that anthropogenic GHG increase causing water vapour increase doesn’t correlate all that well no matter how you’re measuring it.

  61. Perhaps I am missing something here but specific humidity cannot be measured at a single altitude as it is the measure of humidity in a volume. A two dimemsional plane, at any altitude, has no volume.

  62. Anthony,
    I think you’ve read the data incorrectly (hey, it happens) and I look forward to your clarification.

  63. The Miskolczi paper, “Greenhouse Effect in Semi-Transparent Planetary Atmospheres” adds energy constraints to the standard greenhouse theory and shows that the strength of the greenhouse effect is near the maximum. This implies that adding CO2 to the atmosphere would reduce the relative humidity, as CO2 emissions replace water vapour to maintain a constant greenhouse effect, assuming a constant external forcing (Sun and albedo). So, has relative humidity been falling with increasing CO2 concentrations?

    Here is a graph of global average annual relative humidity at various elevations in the atmosphere expressed in milli-bars (mb) from 1948 to 2007. The data is from the NOAA Earth System Research Laboratory http://www.cdc.noaa.gov/cgi-bin/Timeseries/timeseries1.pl.

    This shows that the relative humidity has been dropping, especially at higher elevation allowing more heat to escape to space. The bottom curve labeled 300 mb is at about 9 km altitude, which is in the middle of the predicted (but missing) tropical troposphere hot spot. This is the critical elevation as this is where radiation can start to escape without being recaptured. The average annual relative humidity at this altitude has declined by 21.5% from 1948 to 2007! This explains why the computer model predicted hot spot, which assumes a constant relative humidity, is absent from observations.

  64. To follow up my last on the mass balance issue on water vapor loss to sea level rise :

    Just back of the envelope, but the mass of water vapor represented by the recent downtrend (1990-2008) in specific humidity (~.03 g/kg) compares to the uptrend (satellite measure – 1993-2005) of ~45mm rise in sea level over 361 sq. km of ocean to within about 95% of the same mass of water.

    I’m just sayin’ …

  65. On another forum there is a discussion of greenhouse effect on Mars.
    This has a 95% CO2 atmosphere and nearly no water vapor or clouds to confuse the issue. Much the same axial tilt as Earth and same length of day. This ought to be a good natural experiment.

    Of, yes, there’s 30 times as much mass of CO2 over each square meter of Mars as on Earth.

    Estimates of greenhouse effect on Mars seem to be around 5 to 10C warming. I’m not sure how this was calculated. A back of the envelope calculation got me 10C with some simple assumptions based on Earth – Mars comparisons.

    Searching for Mars “greenhouse effect” gets you lots of hits by people who want to Terraform it!

    Seems to me until somebody figures out the greenhouse effect on Mars to better than a factor of 2 we’re wasting our time debating the CO2 contribution on Earth.

  66. On the issue of CO2 freezing out … The freezing point (solid/vapor) at atmospheric pressure is about -78 ºC, but this applies to pure CO2 vapor. Since the atmosphere contains only about 380 ppm CO2, the temperature would have to drop to about -142 ºC before CO2 would begin to condense out. So, there is no chance of any CO2 condensation on planet earth.

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  68. The lead post says the CO2’s contribution to the greenhouse effect:
    “carbon dioxide, which causes 9–26%”, then says “Note the range of uncertainties”.

    This range is not due to uncertainty, but due to different methods of calculating the effect. The contributions of each greenhouse gas component (water vapor & clouds, CO2, O3 etc.) are not additive due to over-lapping absorbing spectra, and nature does not allocate the effect to the various components. If one removes some CO2, water vapor will capture most of the long wave-length radiation (LWR) that the CO2 would have captured.

    If all CO2 is removed from the atmosphere (all other components unchanged) the greenhouse effect would be reduced by 9%. If all components are removed except CO2, CO2 would still cause 26% of the effect. The sum of each component for the two methods do not sum to 100%. If the methods are normalized and averaged, CO2 accounts for about 16% and water vapor & clouds for 75% of the greenhouse effect. These numbers are from the GISS climate model. Further details are at http://members.shaw.ca/sch25/FOS/CO2_Versus_Water.html

    However, adding CO2 to the atmosphere does not add to the greenhouse effect because the strength of the effect is controlled by the overall energy balances which is unchanged. So adding CO2 just rains out extra water vapor to maintain a constant greenhouse effect.

    Mark Andrew (16:32:31) says:

    Greenhouse effect = 30 degrees Celsius.
    Water = 70% of 30 degrees = 21 degrees.
    Reduction in water vapour content from graph = 10% (from about 0.2 to 0.1 8)
    Predicted reduction in temperature based on water vapour greenhouse effect from graph = 2.1 degrees.

    This is wrong as it does not account for the over-lapping absorbing spectra. Other greenhouse gases will capture some LWR not captured by the loss of water vapor.

  69. Ken Gregory 19:46

    “These numbers are from the GISS climate model.”

    With CO2 –>H2O feedback on , or off? The plots show that it should be off.

  70. Although it is an interesting observation, it has very limited implications. NOAA itself warns about how small data we have about water vapor (http://lwf.ncdc.noaa.gov/oa/climate/gases.html) where they say “Also, while we have good atmospheric measurements of other key greenhouse gases such as carbon dioxide and methane, we have poor measurements of global water vapor, so it is not certain by how much atmospheric concentrations have risen in recent decades or centuries, though satellite measurements, combined with balloon data and some in-situ ground measurements indicate generally positive trends in global water vapor.”

    There are so many uncertainties associated with measuring water vapor. Satellites probably could do a better job now for profiling concentrations with respect to altitude using perpendicular and diagonal measurements, but earlier satellites did not have that capability. If we go way back to 1950s and before, they were using only ground based measurements, which cannot account for the variability in water vapor (both with respect to time and location). There is also a disconnect when ground based measurements were supplemented with satellite measurements when satellites data became available. Even now, satellite measurement of water vapor is only 30 to 40 % accurate. So, I think the story is interesting, but beyond that I see no reason to make any additional speculation relating to global warming.

  71. anna v,

    These numbers are from model simulations were, for example, all CO2 is removed keeping all other gases constant and recording the change in the greenhouse effect. So, removing all CO2 from the atmosphere but keeping the water vapour concentrations constant reduces the greenhouse effect by 9%. This is no feedback.

    But, as I mentioned, increasing the CO2 concentration does cause a reduction in water vapour.

    There is a near infinite supply of greenhouse gases available to the atmosphere in the form of water vapor from the ocean to provide the greenhouse effect, but the relative humidity in the atmosphere is much less than one. Therefore, there must be some greenhouse equilibrium mechanism to control the relative humidity, and therefore the strength of the greenhouse effect. Otherwise, climate would be very unstable.

    If some temporary disturbance adds a large amount of greenhouse gases into the atmosphere, temperatures will temporarily increase, as it did in 1998 due to the super El Nino. If one believes that a temperature rise will cause more water vapor, which will cause more temperature rise, and more water vapor yet again, one would expect temperatures to continue to rise after 1998, and result in a run-away effect. But the opposite happened, temperatures fell as the greenhouse equilibrium mechanism restored the balance. The extra greenhouse gases rained out to restore the equilibrium.

    The new Miskolczi theory describes this missing greenhouse equilibrium mechanism. He shows that the classical theory does not include all the necessary energy constraints. When these constraint are included in a new theory, the strength of the GHE is determined analytically. The result shows that the Earth’s atmosphere is maintained at a nearly saturated greenhouse effect. The greenhouse sensitivity to a doubling CO2 is about 0.24 K.

    This greenhouse equilibrium mechanism doesn’t care if an initial increase of greenhouse gases was water vapor or CO2. If somehow we suddenly released an amount of CO2 to the atmosphere equal in GHG effect of the 1998 El Nino water vapor, the temperature effect would be the same. Temperatures would increase by 0.6 Celsius, but would fall within a year to the original temperature, as the greenhouse equilibrium mechanism restores the greenhouse strength to the equilibrium value by raining out the excess greenhouse gases. Adding man-made CO2 to the atmosphere just rains out almost an equivalent amount of water vapor.

  72. The first question I have is are the specific humidity data reliable? I’d like to know how it is measured, what parts of the planet are measured, how often, and what assumptions and extrapolations are being made. Are there any independent confirmations of this data? I am highly skeptical of any kind of global measurement. If the data aren’t good, then there’s not much point in trying to determine it’s meaning.

  73. Please pardon my utter lack of knowledge here, but how can the amount of water vapour in the atmosphere be falling if the cloud cover is increasing?

  74. Ok, I’ll throw my $.02 into this discussion:

    First, about the 300 mB cutoff… Just a guess, but it probably represents an arbitrary, but convenient cutoff level, where the total amount of water vapor located at elevations higher (lower pressures) is simply negligible in comparison to what lies below. The upper 30% of the atmospheric mass simply can’t hold much water because of the low temperatures.

    Second, with regard to Sea Level changes corresponding to the specific humidity changes… please check that math! A change of 0.03 g/kg dry air amounts to what… something around 0.3mm depth of water if you could possibly condense it all and bring it to earth… if you could then get all that water to the oceans, it would be less than 1/2 mm change in ocean depth. Remember that you’ve only got roughly 1kg of air above each square centimeter of earth’s surface.

    Ok, so this was only about $.002
    DaveK

  75. Uh-oh. If adding CO2 decreases water vapor I can see the next scare as being “more CO2 causes less water in the atmosphere which means less rain”.

    Or is it that, that means more rain as the excess water is rained out? However if we stop adding CO2 there will at equilibrium be less water in the atmosphere which surely means less rain in the long term.
    No runaway greenhouse though.

  76. I took a look at what I think is the source of this data, and it shows specific humidity values at various levels from the surface up to 300 mB. There is no data above. It also allows you to “combine” data for several elevations. Therefore, I would presume it is a plot of the average specific humidity using the averaged value up to the 300mb elevation.

    I didn’t take the time to actually do the plot, since it’s difficult to extract more than one year’s worth of values at a time.

    Dave K

  77. This graph then from NOAA’s Earth System Research Laboratory, showing specific humidity of the atmosphere up to the 300 millibar pressure level (about 8 miles altitude) is interesting for it’s trend:

    “up to”? Surely that should be “around”? i.e. in the Stratosphere (did I mention that’s cooling, so you wouldn’t immediately expect it to have increasing WV levels?).

    Yes there’s interesting research on stratospheric Wv trends, involving changes in CH4 (IIRC the levelling of CH4, that’s now ending), and stratospheric transport(Brewer-Dobson) changes. But as I’m busy with the Arctic right now, I can’t spare the time to discuss further.

    So when we see atmospheric water vapor dropping as shown in the NOAA ESRL graph above, you know it has to have an effect on our overall planetary energy budget, the question that will be argued is; “how much”?

    And the answer is “not a great deal” as the major impact of changes in water vapour on GEB is in the IR blocking of the enhanced greenhouse effect below the effective radiating layer in the troposphere.

    The upshot of which:
    This doesn’t present the problem for consensus science that your post initially suggested, and from my re-reading still seems to imply.

    Cobbly Out.

  78. Confirm data is only available for pressures up to an altitude equivalent to 300mb.
    250mb – no data is available
    1000mb – I think this graph gives the global average value

  79. Trent- you say “On the issue of CO2 freezing out … The freezing point (solid/vapor) at atmospheric pressure is about -78 ºC, but this applies to pure CO2 vapor. Since the atmosphere contains only about 380 ppm CO2, the temperature would have to drop to about -142 ºC before CO2 would begin to condense out. So, there is no chance of any CO2 condensation on planet earth.”

    I thought the total pressure above a solid or liquid is what determines the phase transition temperature, not the partial pressure. If not, can you provide me some information on this? I did some looking but could not find anything specifically addressing CO2. It is also interesting that the poles on Mars do not seem to get colder than about -140 C, both poles have condensed solid-phase CO2 during their respective winters, and the atmosphere on Mars is 0.007 bar of 95% CO2, all of which support your contention of a suppressed freezing point at low pressure (which is consistent with the CO2 phase diagram). But, that is not the same situation on Earth where the atmospheric pressure is 1 bar.

  80. So the lower limit of the graph in terms of altitude is 8 miles up, where pressure is at 300 mb if you were standing at that altitude, and the upper limit is wherever pressure is 0, which in my mind equates to weightlessness if you were standing at that altitude. Is that right?

    REPLY: Correct except you can’t stand in zero gravity

  81. If the data comes from the PSD monthly-average multilevel dataset, there is no data at elevations above (pressures lower than) 300 mB. But perhaps it comes from another source?

    DaveK

  82. Sorry Anthony, you are still incorrect.

    The graph you show in your post is the specific humidity at 300 mb. It is NOT from 0 mb to 300 mb. You can easily recreate this graph for yourself at the link I gave in my previous post, recopied here:
    http://www.cdc.noaa.gov/cgi-bin/Timeseries/timeseries1.pl

    Unfortunately, the graph is not labeled with the elevation of the data (300 mb). You can create other graphs from this site of data of from surface up to 300 mb, (surface, 1000mb, 925, 850, 700, 600, 500, 400 or 300 mb). All of these graphs have exactly the same label.

    If you click on the graph in your post to display only the graph from the NOAA site, you can see the full URL, which shows all the parameters used to create the graph, including “level=300”, meaning the graph is showing data at the 300 mb level. The “up to 300 mb only” on the graphs means that data is available from surface up to the 300 mb level only, so don’t try to plot the 200 mb level, as you will get a error message.

    REPLY: Hmmm, so the “up to” portion of the label put there by ESRL is completely wrong and misleading. Thanks for the note.
    This is annual data, so use “Seasonal data”, First month=Jan, second month=Dec. Use Area weight grids=Yes.

    In my previous posting, I presented a graph of Relative Humidity at several levels, copies here: http://members.shaw.ca/sch25/FOS/GlobalRelativeHumidity.jpg
    This shows that the relative humidity has dropped 21.5% from 1948 to 2007.

    I will create a composite graph of Specific Humidity now and post it shortly.

  83. Thanks for the reply. If the greenhouse gas, as I understand, works this way, then I don’t understand how there can be predictions of huge temperature increases. Although I must admit I am a lowly chemical engineer and not a fancy climate modeler. Perhaps the climate modelers have some special laws of thermodynamics that they use that I’m unaware of.

    If we’ve survived the 100 ppm or so of CO2 increase in the atmosphere it would appear to me that the next 100 ppm shouldn’t be nearly as bad. Let’s see, the last 100 ppm resulted in an explosion of wealth and doubling or so of human life expectancy – we should be so lucky in the future.

  84. This is highly disturbing, if part of a longer term trend. Combined with the era scale trend toward slow decline of CO2 (which man made GHGs may or may not ultimately be able to mitigate) this means two key factors for biosphere success are in decline. We should be plotting our exit strategy. It will either have to be terraforming right here on Earth, or, colonization of space.

    REPLY: Check the update in the article – Anthony

  85. Not to go overboard on the doom and gloom here (my main objective is to incite serious efforts to conquer space) when you consider the harsh realities regarding fossil fuel costs and apparent future supply curve, by a couple hundred years from now, unless we develop methods for cheaply synthesizing oil, our ability to add CO2 will no doubt be in steep decline. Barring mass burning of forests, or other highly drastic countermeasures, we are going to have to eventually face the music regarding the apparent long term CO2 trend, once it is reestablished.

  86. Anthony, thanks for correcting your post. Could you also kindly correct my name from Kevin to Ken? Thanks.

    In my previous posting, I had promised to post a composite graph of specific humidity at various elevations. On second thought, specific humidity varies greatly at different elevations, so the line at 300 mb shows as an almost straight line at the bottom of the graph due to the large scale range. Expanding the scale at the 300 mb line would show the identical line shown in the lead post.

    The specific humidity graph is here:

    and the relative humidity graph is here:

    I had previously asked if it was possible to insert graphs directly into posts. I got no reply. I had copied the appropriate tag codes (from ClimateAudit.org) but that didn’t work. There are no “img” tags shown in your tag list.

    All climate models use a completely absurd assumption that specific humidity is constant when CO2 concentrations increase. This violates fundamental energy conservation laws. There are not separate energy balance equations for different greenhouse gases. There is not one set for water vapor, and a different set for CO2; there is one set of energy balance equations for the total atmosphere including the sum of all greenhouse gases.

    Why is the relative humidity at 300 mb at 38% and not at 60% or 95%, or vary randomly? It is at its value due to the laws of physics, which are not included in the climate models. The energy conservation principles controls the strength of the greenhouse effect, not just one particular gas, so changing the amount of CO2 will cause an offsetting change in H20. Water specific humidity would be constant only if other greenhouse gas concentrations are held constant.

    A summary of the correct energy balance laws that control the strength of the greenhouse effect is here:
    http://hps.elte.hu/zagoni/Proofs_of_the_Miskolczi_theory.htm

  87. I can’t resist. If increases in CO2 increase precipitation then we get a double bonus for plant growth. There seems to be some serendipity going on. Even if land gets soggy, it will be good for rice, which the Chinese will appreciate.

  88. I created a graph of global relative humidity of levels of each 100 mb from 300 to 700 mb here:

    This expanded scale more clearly shows the declining relative humidity.
    Remember that the highest curves, 300 mb and 400 mb are most important, as these are in the predicted hot spot and at the characteristic emission level. Water vapor changes near the surface have little effect on the greenhouse effect because long wave-length photons captured here and emitted would be recaptured again and would not escape to space.

    Apart from simple logic that the constant relative humidity assumption used in climate models is ridiculous (as previously discussed), this graph proves it to be false, and that water vapor is a strong negative feedback, not a positive feedback.

  89. Ken, Do you have any thoughts on how this (obvious) drop in relative humidity relates to specific humidity, and the relative merits of specific vs relative humidity in looking at thermodynamic effects of changes in water vapor in the atmosphere? Your earlier graphs of specific humidity appeared to show no decline, and perhaps a slight increase.

  90. Hi David,

    I have read your excellent four part critique of the Miskolczi theory at our website Niche Modelling at http://landshape.org/enm/radiative-equilibrium-miskolczi-part-4/

    This is a must read for anyone concerned about the world spending trillions of dollars to slow emissions of a completely beneficial by-product of industrialization – CO2.

    If CO2 were held constant, an increase of external Sun forcing would cause specific humidity to increase with increasing global temperatures, but there should be little or no change to relative humidity. Increasing the Sun’s forcing would also increase the greenhouse effect. The greenhouse effect G would increase by 1/2 of the increase in the Sun forcing F, where F in net of albedo, so includes the Svensmark’s theory of the Sun changing the amount of cloud cover via cosmic rays.

    When we say there is an almost constant greenhouse effect, we mean it is constant despite increasing CO2 assuming a constant external forcing (Sun and albedo).

    In the real atmosphere, the increasing CO2 and increasing Sun’s forcing over most of the 20th century would also cause the specific humidity to increase. At lower elevations specific humidity has increased, but this has little effect on the greenhouse effect as the large amount of water vapor already captures all LWR. At higher elevations specific humidity has decreased. We expect overall the specific humidity to increase due to increasing Sun forcing and decreasing relative humidity especially at higher elevations due to increasing CO2 concentrations.

  91. Ken, thanks for the kind words, although it is unfinished and going to take another 4 posts at least to get through even the radiative equilibrium part of M’s paper. I thought your review of AGW issues was the best I have seen. I will certainly give you my thoughts on your Miskolczi piece after I have read it.

    The water vapor story is obviously a major piece of the puzzle and I should come to grips with the issues and the facts surrounding it. Your explanation above seems to suggest that papers claiming increase in water vapor and positive feedback, and facts showing relative humidity declining, could both be right. It seems contradictory on the face of it.

  92. Apologies for a totally off topic post but I don’t know any other way of bringing it the the attention of this blog.
    This site/papers on sustainable energy gives a lot of facts based the UK energy usage which appears to kick a lot of holes in the wind/tidal power argument as a viable alternative source http://www.withouthotair.com/

  93. Ken Gregory wrote: “Hi David, I have read your excellent four part critique of the Miskolczi theory at our website Niche Modelling at http://landshape.org/enm/radiative-equilibrium-miskolczi-part-4/

    This is a must read for anyone concerned about the world spending trillions of dollars to slow emissions of a completely beneficial by-product of industrialization – CO2.”

    I agree this is a “MUST READ,” but first, readers might wish to read Ken’s great article found at http://www.friendsofscience.org/assets/documents/The_Saturated_Greenhouse_Effect.htm.

    Jack Koenig, Editor
    The Mysterious Climate Project
    http://www.climateclinic.com

  94. If John McLondon’s quote of NOAA “Also, while we have good atmospheric measurements of other key greenhouse gases such as carbon dioxide and methane, we have poor measurements of global water vapor,” is correct (and I have no reason to doubt it), it means we know bugger all about something thought to contribute 70 – 90% of the “greenhouse effect” and yet it has been possible to create the illusion that we should be “spending trillions of dollars to slow emissions of a completely beneficial by-product of industrialization – CO2.” (McGrats). That’s the real concern about “global warming”

  95. Pingback: A Window on Water Vapor and Planetary Temperature - Part 2 « Watts Up With That?

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  97. The latest claim by the proponents of man caused global warming attributed to higher levels of CO2 is more of the “sky is falling” rhetoric but now in relation to elevated CO2 levels in the oceans. They claim that increased levels of CO2 in the atmosphere caused by burning fossil fuels has tipped the balance of nature and the natural carbon sinks other than the oceans are no longer able to stabalize atmospheric CO2 and now the ocean has to absorb more and more CO2. Their claim is this is causing the oceans to become more acidic and this threatens all life on earth. Does anyone have access to any studies that confirm or contradict rising acidity in oceans or even large fresh water bodies of water?

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