Study: ‘Back radiation’ not a component of climate change

Written by John O'Sullivan

2019 study published in Geophysical Research Letters (GRL) affirms Downward Longwave Radiation (DLR) “cannot be considered an independent component of the surface energy budget.”

The conclusion affirms the science of researchers at Principia Scientific International.

The paper, ‘Does Surface Temperature Respond to or Determine Downwelling Longwave Radiation?‘ was published on February 19, 2019. The Abstract reads:


Downward longwave radiation (DLR) is often assumed to be an independent forcing on the surface energy budget in analyses of Arctic warming and land‐atmosphere interaction. We use radiative kernels to show that the DLR response to forcing is largely determined by surface temperature perturbations. We develop a method by which vertically integrated versions of the radiative kernels are combined with surface temperature and specific humidity to estimate the surface DLR response to greenhouse forcing. Through a decomposition of the DLR response, we estimate that changes in surface temperature produce at least 63% of the clear‐sky DLR response in greenhouse forcing, while the changes associated with clouds account for only 11% of the full‐sky DLR response. Our results suggest that surface DLR is tightly coupled to surface temperature; therefore, it cannot be considered an independent component of the surface energy budget.

Plain Language Summary

Longwave radiation, often referred to as “thermal” or “infrared” radiation, emitted downward by Earth’s atmosphere is a primary contributor to the surface energy budget. Numerous studies have invoked longwave radiation as a driver of surface warming. This paper shows that this line of reasoning fails to account for the strong control surface temperature exerts on longwave radiation. Using radiative kernels, matrices that quantify the longwave radiation response to a climate perturbation (like global warming), we argue that any surface temperature anomaly will generate a downward longwave radiation response. This constitutes a feedback between the Earth’s surface and its atmosphere. The kernels show large longwave responses to perturbations in the lowest part of the atmosphere and almost no response to perturbations at high levels; by vertically integrating the kernels, we can ignore the vertical structure of climate perturbations. Using this modification, we predict the longwave radiation response to a warming world using only the surface changes. Our prediction agrees with climate model output, suggesting that the longwave radiation response is determined primarily by surface temperature. Further, the cloud contribution to changes in longwave radiation is small. These results provide clarity on how changes in the surface energy budget should be analyzed.

Read the full paper at


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Comments (2)

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    Paldies pat jūsu darbu.

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    D J C


    Yes John O’Sullivan Prof Claes Johnson and I wrote about how back radiation is scattered and its energy not converted to thermal energy in the warmer surface back in 2012. You praised my paper and sent it it other websites. But now PSI has no explanation of surface temperatures on Earth, let alone Venus, whereas I have and I gave PSI my ground-breaking scientific work in 2013 when Joseph Postma and Pierre Latour realised it proved Postma’s first paper wrong. And it is wrong: solar radiation cannot make the average temperature of the Moon’s surface greater than zero C and the Earth’s surface receives only about half as much direct solar radiation. The Venus surface receives only about one-eighth of what Earth’s surface receives. To explain the Venus surface temperature with radiation would require in the vicinity of nearly 20,000W/m^2 coming out of the base of the atmosphere, when the Sun’s radiation is something like only 2,600W/m^2 at the top of the Venus atmosphere. The Venus atmosphere cannot multiply energy, sending so much more out of its base than that which enters it at the top. Simple experiments with electric bar radiators and a thermometer PROVE that radiative fluxes from different sources cannot be added arithmetically and the sum used in Stefan-Boltzmann calculations to explain the resulting mean surface temperature.

    Solar radiation reaching the surfaces of these planets is NOT what explains the warming of these surfaces on the sunlit side. Instead it is the downward “free” (or “natural”) convective heat diffusion process that supplies the necessary thermal energy. I have PROVED that this happens and the process is indeed increasing entropy and is thus a direct consequence of the Second Law of Thermodynamics.

    There’s a US $10,000 donation awaiting PSI if they can prove wrong my “heat creep” hypothesis which is explained directly from the Second Law of Thermodynamics in the 2013 paper they rejected without right of reply. Ever since they deny me right of reply and delete my comments.

    If you, John O’Sullivan (with your background in journalism, not physics) publish an article supposedly refuting the physics in my 2013 paper then you don’t get the donation unless you allow my comments on the article (and refutation of their attempt) to stand for at least two months, preferably, in the interests of science, permanently.

    I encourage others to write to John O’Sullivan requesting this open rational climate debate. Over 500 have downloaded the paper free at:

    PSI is covering up Joseph Postma’s false physics. John O’Sullivan deletes refutations of it.

    This is the seventh time I need to repost this:

    Joseph (“Sunshine-does-it-all”) Postma makes a mockery of PSI. Solar radiation impinging on the surfaces of planets like Earth and Venus does NOT account for the global mean surface temperature. Our Moon’s surface receives about twice as much direct solar radiation as does Earth’s surface, yet the Moon’s global mean surface temperature is well below zero C – some say around -25C. Even Roy Spencer gets it right in his refutation that Postma cites without understanding why Spencer was at least right on that score!

    Postma’s errors …

    (1) He forgets to deduct 20% of the solar radiation that is absorbed by the atmosphere.

    (2) He forgets that the surface is simultaneously losing energy by evaporation and conduction into the atmosphere.

    (3) He forgets that the effective flux has to be multiplied by the sine of the angle made with the horizontal. That’s why you don’t get sunburnt at 7:30am.

    (4) He forgets that Stefan-Boltzmann calculations yield temperatures at equilibrium, that taking a long time to achieve. In mid-summer at noon on a clear day the bare rocks at the top of Mt Everest receive over 1,000W/m^2 and Postma’s calculations would say that is equivalent to over 90C, but there is not enough time in the day to achieve this.

    It is about time that John O’Sullivan got Postma’s writings peer-reviewed by anyone with a background in physics and an ounce of common sense.

    Apparently Postma never learned that the brilliant physicist Josef Loschmidt explained back in 1876 how gravity establishes the temperature gradient in the troposphere at the molecular level, and thus sets the surface temperature.

    Finally, Postma claims that the Second Law of Thermodynamics says heat is always from hot to cold. In fact it says: “In a natural thermodynamic process, the sum of the entropies of the interacting thermodynamic systems increases.” Under the force of gravity (or centrifugal force in a vortex cooling tube) there can be heat diffusion from cooler to warmer regions that is indeed increasing entropy because entropy is also affected by changes in gravitational potential energy.

    As John O’Sullivan will just delete this comment without even reading it, may I suggest that some other reader(s) write to him directly before PSI becomes the laughingstock of both alarmists and skeptics.

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