Shock News : The Most Important Greenhouse Gas Varies Between 30,000 ppm And 1,000 ppm

How can we ever stabilize the climate with water vapor concentration varying by so much from day to day and place to place? We are trying to fine tune CO2 within a few hundred ppm, while H2O is all over the map.

Can’t someone in government bring all that water vapor under control?

About stevengoddard

Just having fun
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9 Responses to Shock News : The Most Important Greenhouse Gas Varies Between 30,000 ppm And 1,000 ppm

  1. Glen Shevlin says:

    have to contain all the hot air on capitol hill(s) first

  2. Scott says:

    Be careful Steve, you may give them more ideas.


  3. Scott says:

    And where did you get that 30,000 ppm number? The vapor pressure of water at 38 C is 0.0652 atm…aka 65200 ppm. I could see it reaching that value in tropical regions. Heck, even in the midwest I remember reaching 95% RH on days of 95 F…that’s 52,600 ppm.

    Also, where’d you get the 1000 ppm? I assume the vapor pressure of H2O at -90 F (Vostok) is below 0.001 atm…my Antoine constants aren’t valid below 0 C, and I’m too lazy to look up the Pvap at that low a temperature. Can anyone else find a number for that?


    • I don’t think it would be possible to have 95% humidity and 95 degrees at the same time in Earth’s atmosphere.

      At 0C, the saturated vapor pressure of water is 15% of what it is at 30C. It tails off very slowly below 0C, so my 1,000 ppm is very conservative.

      • Scott says:

        I’ll take your point on 95/95…that’s what I get for listening to the adults when I’m a kid. Guess they didn’t understand that the RH of 95% in the early morning didn’t stay an RH of 95% all day when it hit 95 F in the afternoon. On the other hand, a 95/95 equates to a dewpoint of ~93 F. And this value HAS been reached on Earth. The record dew point is 94 F, see here:

        That’s 53,700 ppm, so not horribly far off your number (though expanding your range quite a bit).

        On the other hand, I 100% disagree with your statement that water’s vapor pressure tails off very slowly below 0 C. A quick search found this site:

        Here, the vapor pressure is seen to drop by 54% from just 0 C to 10 C. Digging a little further finds this amazingly useful table:

        Click to access pvh2o.pdf

        So what is the vapor pressure at Vostok when it’s -90 F (-68 C)? Well, that table shows the vapor pressure to be 5.33 ppm of 1 atm at -65 C and 2.58 ppm of 1 atm at -70 C. Notice how it dropped by a whopping 52% in just 5 C? Well, we need to account for Vostok’s pressure, which is below 1 atm. Its elevation is 3488 m, meaning its average pressure is 0.616 atm. Interpolating the results from the table and correcting for the lower pressure at Vostok puts us at 5.97 ppm CO2 if the RH is 100%.

        So maybe you want to be conservative with your title and show a range of only 30x in H2O concentration. But just from what I’ve shown here we can safely say that the H2O ppm concentration varies from 6-53,000 ppm at the Earth’s surface…a range of 8800x if using ppm as your unit (more if you consider absolute humidity b/c Vostok doesn’t take a hit from being higher up).

        Clearly, regulating H2O should be extremely important to the greens. They better start a bill for making all the water vapor in the atmosphere organic!


      • Scott says:

        Dang multiple links and moderation!

  4. Al Gored says:

    Seems clear that a system of globally traded water vapor credits and various derivatives and other financial instruments managed by Goldman Sachs would solve this problem.

    There will be sacrifices of course, for the children. And, unfortunately, the geysers at Yellowstone must be capped. Fortunately for all of use, national park regulations already prohibit the explosion of any volcanic activity there as that would disturb the bears.

  5. nofreewind says:

    and these graphs global water vapor and humidity trending down.
    a real scientist would ask, “how could that be”?

  6. Andy Weiss says:

    Damned evaporation!! Needs to be stopped at all cost.

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