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The atmospheric greenhouse effect, an idea that many authors trace back to the traditional works of Fourier (1824), Tyndall (1861), and Arrhenius (1896), and which is still supported in global climatology, essentially describes a fictitious mechanism, in which a planetary atmosphere acts as a heat pump driven by an environment that is radiatively interacting with but radiatively equilibrated to the atmospheric system. According to the second law of thermodynamics, such a planetary machine can never exist. Nevertheless, in almost all texts of global climatology and in a widespread secondary literature, it is taken for granted that such a mechanism is real and stands on a firm scientific foundation. In this paper, the popular conjecture is analyzed and the underlying physical principles are clarified. By showing that (a) there are no common physical laws between the warming phenomenon in glass houses and the fictitious atmospheric greenhouse effects, (b) there are no calculations to determine an average surface temperature of a planet, (c) the frequently mentioned difference of 33° is a meaningless number calculated wrongly, (d) the formulas of cavity radiation are used inappropriately, (e) the assumption of a radiative balance is unphysical, (f) thermal conductivity and friction must not be set to zero, the atmospheric greenhouse conjecture is falsified.

In this journal, Gerhard Gerlich and Ralf D. Tscheuschner claim to have falsified the existence of an atmospheric greenhouse effect.¹ Here, we show that their methods, logic, and conclusions are in error. Their most significant errors include trying to apply the Clausius statement of the Second Law of Thermodynamics to only one side of a heat transfer process rather than the entire process, and systematically ignoring most non-radiative heat flows applicable to the Earth's surface and atmosphere. They claim that radiative heat transfer from a colder atmosphere to a warmer surface is forbidden, ignoring the larger transfer in the other direction which makes the complete process allowed. Further, by ignoring heat capacity and non-radiative heat flows, they claim that radiative balance requires that the surface cool by 100 K or more at night, an obvious absurdity induced by an unphysical assumption. This comment concentrates on these two major points, while also taking note of some of Gerlich and Tscheuschner's other errors and misunderstandings.

It is shown that the notorious claim by Halpern et al. recently repeated in their comment that the method, logic, and conclusions of our "Falsification Of The CO₂ Greenhouse Effects Within The Frame Of Physics" would be in error has no foundation. Since Halpern et al. communicate our arguments incorrectly, their comment is scientifically vacuous. In particular, it is not true that we are "trying to apply the Clausius statement of the Second Law of Thermodynamics to only one side of a heat transfer process rather than the entire process" and that we are "systematically ignoring most non-radiative heat flows applicable to Earth's surface and atmosphere". Rather, our falsification paper discusses the violation of fundamental physical and mathematical principles in 14 examples of common pseudo-derivations of fictitious greenhouse effects that are all based on simplistic pictures of radiative transfer and their obscure relation to thermodynamics, including but not limited to those descriptions (a) that define a "Perpetuum Mobile Of The 2nd Kind", (b) that rely on incorrectly calculated averages of global temperatures, (c) that refer to incorrectly normalized spectra of electromagnetic radiation. Halpern et al. completely missed an exceptional chance to formulate a scientifically well-founded antithesis. They do not even define a greenhouse effect that they wish to defend. We take the opportunity to clarify some misunderstandings, which are communicated in the current discussion on the non-measurable, i.e., physically non-existing influence of the trace gas CO₂ on the climates of the Earth.

Based on new radiative transfer numerical evaluations, we reconsider an argument presented by Schack in 1972 that says that saturation of the absorption of infrared radiation by carbon dioxide in the atmosphere sets in as soon as the relative concentration of carbon dioxide exceeds a lower limit of approximately 300ppm. We provide a concise brief and explicit representation of the greenhouse effect of the earth’s atmosphere. We find an equilibrium climate sensitivity (temperature increase $\mathrm{\Delta }T$ due to doubling of atmospheric ${\mathrm{\text{CO}}}_2$ concentration) of $\mathrm{\Delta }T\simeq 0.5^{\circ }$C. We elaborate on the consistency of these results on $\mathrm{\Delta }T$ with results observationally obtained by satellite-based measurements of short-time radiation-flux versus surface-temperature changes.

Earth’s climate has experienced a rise of 0.8°C in global surface temperature during the 20th century caused by increased atmospheric concentration of biogenic gases that contribute to the greenhouse effect. Greenhouse effect occurs by contribution from fossil energy, deforestation and degradation of soils. General circulation models predict rising atmospheric CO₂ concentration, resulting in temperature increases from 1.5°C to 5.5°C in the 21st century, and 0.60–1.0m rise in sea level. Impacts include degradation of natural resources, reduced agricultural production and human dislocation. Consider the major contributors of biogenic gases to get the largest impact in selection of mitigation and adaptation methods to climate conditions.

Cycles of glaciation with an average period of ~100 kyr are mediated by impacts of cometary bolides. Ice-age conditions are dry and dusty with low rates of precipitation. Comets in the mass range 10¹⁵–10¹⁶ g impacting the oceans could release enough water vapour into the atmosphere to enhance a depleted greenhouse effect. The energy deposited in the oceans would also warm the surface layers, thus starting up an evaporation-precipitation cycle which ushers in warmer interglacial interludes. The latter have neutral stability and are necessarily short-lived, eventually drifting back to glacial conditions on timescales of ~10 kyr.