New Study Affirms Temperatures Determine Greenhouse Gas Forcing Trends, Not The Other Way Around

CO2 and water vapor greenhouse effect impacts are not independent climate forcings . A new study affirms the “variance in the radiance in these channels is primarily controlled by…temperature” and “atmospheric absorption is strongly saturated in these [CO2, water vapor] channels”.

It has previously been established that greenhouse gas (water vapor, CO2) forcing “cannot be considered an independent component of the surface energy budget” because “anomalies in the downward longwave flux at the surface primarily arise as a consequence of surface temperature anomalies, rather than being the cause of those anomalies” (Singh and Polvani, 2020, Zeppetello et al., 2019).

Image Source: Singh and Polvani, 2020, Zeppetello et al., 2019

Feldman et al. (2015) admit they had to “construct” model-based spectra to simulate a CO2 signal in their seminal paper purporting to show CO2 changes cause temperature changes. This is because the temperature and water vapor levels primarily determine the overall longwave forcing (clear-sky) trends.

Image Source: Feldman et al., 2015

Now, a new study (Liu et al., 2022) affirms the overall trends in downwelling longwave radiation (DLR) from CO2 and water vapor are determined by temperature.

“In the opaque portions of the CO2 absorption band (centered at 667 cm−1) and H2O absorption band (1300 – 1800 cm−1), the overall radiance trends are caused by radiance change which is due almost entirely to the increases in the near-surface temperature because the atmosphere is already too opaque to reflect any gas concentration changes.”

This effectively means that greenhouse gases and associated impacts cannot be assumed to be the cause of temperature, but the consequence.

Image Source: Liu et al., 2022

7 responses to “New Study Affirms Temperatures Determine Greenhouse Gas Forcing Trends, Not The Other Way Around”

  1. Petit_Barde

    In radiative heat transfer, a flux alone has no meaning :
    – the energy transfer from body 1 towards body 2 is the difference of the radiative flux emitted by body 1 and absorbed by body 2 minus the radiative flux emitted by body 2 and absorbed by body 1.

    If the fluxes’ difference is positive then body 1 (radiatively) heats body 2 (some energy is actually transfered from body 1 to body 2).

    In the case of the Earth surface (body 1) and the atmosphere (body 2), this energy transfer is always positive (upwards) thus the atmosphere cannot heat the surface (by radiative heat transfer), but the opposite is true.

    See Kiehl and Trenberth (1997) or NASA (2009, 2013, …) yearly Earth energy budget :

    This is consistent with the articles above (Singh and Polvani, 2020, Zeppetello et al., 2019 and Liu et al., 2022).

    The IPCC’s trick is to separate the 2 radiative fluxes between Earth surface and the atmosphere and then making up a fuss about the DLR.

    A correct Earth energy budget shows instead that the CO2+H2O mix (mean active gases in the IR spectrum) emits 6-fold more energy in the space (165 – 0 = 165 W/m2) than it absorbs from the Earth surface (350-324 = 26 W/m2).
    Thus IR active gases have a cooling effect on the atmosphere and do not heat the Earth surface, it’s the opposite :
    – by cooling the atmosphere, they also contribute to the Earth surface cooling.

    1. Richard Greene

      Greenhouse gases do not “heat”.
      Nor do they cool Earth’s surface.

      They only impede Earth’s ability to cool itself.
      They form a partial barrier between Earth’s surface and the infinite heat sink of outer space. Based on lab infrared spectroscopy, The “partial barrier” effect for the first 100ppm of CO2 is strong but the effect of CO2 above 400ppm, is weak.

      The alleged water vapor positive feedback that multiplies the assumed small effect of CO2 alone by 2x to 4x seems greatly exaggerated. Instead of alt-science on CO2, we climate realists need to persuade people that more CO2 is not dangerous and Nut Zero is not necessary.

      Alt-science (and local climate reconstructions) is not aimed at the primary goal of ending climate scaremongering (50+ years of predictions of climate doom).
      This is a climate propaganda war and we climate realists are losing.

  2. Phil Salmon

    These important studies affirm that the CO2 warming story rests on an inversion of cause and effect.
    The atmosphere is not warm because of IR.
    The atmosphere emits IR because it is warm.

  3. E. Schaffer

    Of course “back radiation” is a function of temperature, not the other way. What matters instead is how GHGs affect emissions TOA. And there is no “saturation” in this regard.

    However there are overlaps between GHGs themselves and with clouds. And these overlaps are NOT considered when claiming a 3.7W/m2 2xCO2 forcing, and a 1.8W/m2 WV feedback. When you include them these figures turn out a lot smaller. 2xCO2 forcing drops to about 2W/m2 and WV feedback gets crippled to only ~0.65W/m2. All over ECS then is only in the 0.5K range, nothing to worry about.

    1. Richard Greene

      ECS is unknown
      Seems like every scientist has a different number.
      The range of estimates is huge.
      There is a positive feedback in that a warmer troposphere
      holds more water vapor. So far the change in water vapor seems small.

      A positive feedback would eventually cause runaway global warming.
      Since that has never happened, even with CO2 levels believed to be 10x higher than today, there must be a negative feedback that prevents it. I can only speculate that more water vapor in the troposphere leads to more clouds, and more clouds reduce incoming solar energy. That may be completely wrong,
      but something regulates the average temperature to maintain a range that has preserved life on our planet

      1. E. Schaffer

        “ECS is unknown”

        Well, there is a consensus. And what is more, we have hitran and modtran databases, which if they are correct, allow us to look up these figures. And according to all of these 2xCO2 forcing per se(!) is around 3.7W/m2 and WV feedback about 1.8W/m2 per se. One should know this, because it is the core of all ECS estimates.

        Again, the problem is, these figures do not consider overlaps.

        1. Richard Greene

          I don’t care how many databases and studies there are:
          ECS is unknown.

          To know ECS, the exact effect of every other climate change variable would have to be known. We are not even close to having that knowledge.

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