About the Postulates of the Greenhouse Effect Theory
Aleksandr Zhitomirskiy
24 September 2024
The theory of the greenhouse effect is based on assertions accepted without experimental and theoretical evidence: about the heating of the atmosphere due to the Earth's radiation without taking into account thermal conductivity and convection, about the identity of infrared radiation absorbed by greenhouse gases with thermal radiation, about the heating of the Earth by the reverse radiation of greenhouse gases, etc. Experimental data and physical laws related to these postulates are considered. It is concluded that the main ideas of the theory of the greenhouse effect do not agree with the facts.
1. Introduction
Over the past few decades, thousands of articles have been published in scientific literature and the media on the greenhouse effect and its impact on the Earth's climate. The vast majority of these publications claim that the current warming of the climate is global in nature and that it is caused by an increase in the concentration of so-called greenhouse gases in the atmosphere due to industrial development. Before accepting the prevailing consensus, it is crucial to understand the underlying facts and scientific principles of this theory and how they fit in with other established facts. To do this, we should begin by examining the well-known description of the greenhouse effect. In this case, we will consider the statements that the authors of the description accept without proof as postulates.
2. Description of the Greenhouse Effect
Encyclopedia Britannica [1] defines the greenhouse effect as “a warming of Earth surface and troposphere (the lowest layer of the atmosphere) caused by the presence of water vapour, carbon dioxide, methane, and certain other gases in the air. Of these gases known as greenhouse gases , water vapour has the largest effect”. From this definition, at least two statements follow: a) it is
known that the air temperature in the presence of the named gases will be higher, all other things being equal, than without them; b) it is known how to distinguish the role of the named gases in changing the temperature among all other factors.
The description goes on to say: “The atmosphere allows most of the visible light from the Sun to pass through and reach Earth's surface. As Earth's surface is heated by sunlight, it radiates part of this energy back toward space as infrared radiation. This radiation unlike visible light, tends to be absorbed by the greenhouse gases in the atmosphere, raising its temperature. The heated atmosphere in turn radiates infrared radiation back toward Earth's surface”. In this quote, each phrase can be considered as a separate postulate subject to discussion.
A different definition of the greenhouse effect is given in the IPCC 4th report [2]:
“The Sun powers Earth’s climate, radiating energy at very short wavelengths, predominately in the visible or near-visible (e.g., ultraviolet) part of the spectrum. Roughly one-third of the solar energy that reaches the top of Earth’s atmosphere is reflected directly back to space. The remaining two-thirds is absorbed by the surface and, to a lesser extent, by the atmosphere. To balance the absorbed incoming energy, the Earth must, on average, radiate the same amount of energy back to space. Because the Earth is much colder than the Sun, it radiates at much longer wavelengths, primarily in the infrared part of the spectrum. Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect.” The idea that the Earth's thermal radiation is absorbed by all atmosphere (regardless of greenhouse gases?) including clouds is acceptable to any "climate denier"; it is just unclear why it is necessary to limit emissions of CO2 and other greenhouse gases into the atmosphere, as the IPCC insists on.
Antero Ollila's article (2019) is specifically dedicated to defining the greenhouse effect [3]. The definition of the greenhouse effect proposed by this author is: “The Earth’s surface emits LW radiation (infrared radiation) and it transfers heat energy in the form of latent and sensible heating into the atmosphere. Most of the emitted infrared radiation is absorbed by trace gases and clouds in the atmosphere. All three energy fluxes increase the temperature of the atmosphere. The part of the infrared radiation due to these three energy
sources emitted downward from the atmosphere adds to the warming of Earth’s surface by sunlight and it is called the greenhouse effect.” This definition also raises a number of questions that will be discussed below.
3. Postulates and their justification
3.1. Greenhouse gases as the cause of warming
The greenhouse effect is a warming of Earth surface and troposphere (the lowest layer of the atmosphere) caused by the presence of greenhouse gases in the air [1]. - To prove this claim, it is necessary, at the very least, to know all the factors that can influence temperature and to have a scientifically sound method for estimating the contribution of greenhouse gases (if one exists) to the observed temperature change. To our knowledge, there has been no such publication in the literature on the greenhouse effect. There is no evidence of a physical experiment confirming the special role of greenhouse gases in the absorption of heat by the atmosphere.
3.2. The concept of the role of incident solar radiation and Earth radiation
The atmosphere allows most of the visible light from the Sun to pass through and reach Earth's surface [1]. The Sun powers Earth’s climate, radiating energy at very short wavelengths, predominately in the visible or near-visible (e.g., ultraviolet) part of the spectrum [2]. - Both of these statements are inconsistent with the data on the distribution of solar energy falling on the Earth by wavelength [4]. High-energy radiation ( up to 300 nm) is mainly absorbed in the upper atmosphere (especially the stratosphere), but along with near ultraviolet and visible light, infrared radiation also reaches the Earth: the radiation energy in the near infrared region (700-1500 nm) is 38.8%, and in the region above 1500 nm it is 12.4% of the total amount of incident solar energy (solar constant) [4, Table 4].
It is obvious that the earth's surface is heated by visible and infrared radiation; however, it is unclear what role atmospheric gases play in this. In the absorption spectra of atmospheric gases in the visible and near infrared region, absorption bands have been found: for oxygen at 690 and 760 nm, for water vapor at 1400, 1600 and 1900 nm, for carbon dioxide at 2750 and 4250 nm [4] . These bands
belong to the region of wavelengths of incident radiation and, according to the theory of the greenhouse effect, such absorption should reduce the amount of energy reaching the earth's surface. (The greatest effect should be expected from oxygen due to its high concentration and higher energy corresponding to the indicated wavelengths). However, no facts confirming such a decrease in energy have been found.
3.3. Absorption and emission of radiation
To balance the absorbed incoming energy, the Earth must, on average, radiate the same amount of energy back to space [2]. - The basis for such a statement is usually given as the law of conservation of energy. The exact formulation of this law is: energy does not disappear and does not reappear, it passes from one form to another. It follows that part of the absorbed energy can pass into another form and not return to the Earth-atmosphere system in the form of terrestrial radiation.
Part of the thermal energy absorbed by the Earth's surface is spent on evaporating water and melting ice and snow: the latent heat of fusion and evaporation. This energy is spent on breaking the bonds between water molecules in the solid and liquid phases and does not change the temperature of the surface or atmosphere. What A. Ollila calls "latent heating" [3] is in fact the heat released during the reverse process of condensation of water vapor and freezing of liquid water. It is hardly possible to reliably estimate the amount of energy in this case, at least because of the unpredictability of rain and snowfall. Another part of the incident solar energy is irreversibly absorbed by biomass: photosynthesis and heating of flora and fauna. This value also cannot be quantified.
It is also necessary to take into account that different parts of the Earth absorb thermal energy differently. The heat capacity and thermal conductivity of water are several times higher than sand. Accordingly, water absorbs much more heat and gives off this heat much more slowly. The temperature difference between different areas of the surface causes the movement of water and air masses. As a result, part of the absorbed thermal energy is converted into mechanical energy, which is dissipated. Thus, the emitted energy is less than the absorbed energy, and the difference between these values cannot be accurately calculated. The value of the
emitted energy is used in the greenhouse effect theory to calculate the so-called effective temperature using the Stefan-Boltzmann equation. Consequently, the calculated value of the effective temperature (255 K) is not reliable and comparing it with the average global temperature (also a questionable value) is meaningless.
3.4. Identification of infrared and thermal radiation
“As Earth's surface is heated by sunlight, it radiates part of this energy back toward space as infrared radiation. This radiation unlike visible light, tends to be absorbed by the greenhouse gases in the atmosphere, raising its temperature” [1].
Let us begin our discussion of this statement by clarifying the terms. The word "sunlight" obviously refers to visible light (400-700 nm), although the Earth's surface, as mentioned above, is heated by incident solar radiation, which also includes the infrared region. Since this radiation heats the surface, it is certainly thermal radiation, although we do not know for sure in which wavelength range the greatest thermal effect is created. The Earth's infrared radiation, for which the dependence of the radiation energy on the wavelength and temperature is described by Planck's curves, covers the wavelength range from 3000 to 100,000 nm. The maximum energy values on these curves, determined by Wien's law, for the most common temperature range of 273-303 K correspond to wavelengths from 10,600 to 9,500 nm.
No experimental evidence exists that infrared radiation in this range (3000100000 nm) or any part of it is capable of heating any substance. This naturally also applies to the wavelength ranges in which greenhouse gases absorb infrared radiation. It would be more correct to say that the experimental data indicate the absence of heating. Let's look at a specific example. The absorption of infrared radiation by a substance is recorded when recording a spectrum in an infrared spectrometer. The IR spectra of carbon dioxide and sulfur hexafluoride are known, for which the values of the global warming potential (GWP) are related, according to the IPCC, as 1: 23500 [5]. The global warming potential (GWP) description [6] states that SF6, like other "high-GWP gases," traps substantially more heat than CO2 for a given amount of mass. Comparing the known measure in physics of the amount of heat absorbed by a certain mass of a substance, i.e. the
specific heat, sulfur hexafluoride has a lower specific heat than carbon dioxide (0.659 versus 0.844 J/g K). Regarding experimental confirmation of the thermal effect, when recording the infrared spectrum of SF6 at concentrations billions of times more than in the atmosphere, no increase in temperature was observed in the infrared spectrometer cell, as was the case for any other substances. Thus, the assertion that terrestrial infrared radiation is thermal radiation [2] cannot be considered valid.
3.5. Back radiation of greenhouse gases
“The heated atmosphere in turn radiates infrared radiation back toward Earth's surface” [1].
“Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth” [2].
“The part of the infrared radiation due to these three energy sources emitted downward from the atmosphere adds to the warming of Earth’s surface by sunlight and it is called the greenhouse effect” [3]. Let us recall that in this definition the three sources of heat are considered to be the radiation of the earth, 'latent heating” and “sensible heating”. It is unclear what kind of radiation, especially downward radiation, the last two sources might produce. In addition to these statements about the back radiation, it is necessary to recall the quantitative assessment of this value in the Earth's heat balance: 324 W/m2 [7]. It should be noted that this value, according to the same calculations, is almost equal to the total amount of solar energy at the top of the atmosphere (342 W/m2 ) and almost twice the amount of energy absorbed by the Earth's surface (168 W/m2 ). If we take into account that gas molecules can radiate energy in all directions, and the mentioned value of 324 W/m2 refers to the energy flow directed downwards, then the total amount of energy emitted by gases turns out to be three times greater (?!). In the extensive literature on the greenhouse effect, there is not only no attempt to explain this fact, but also no mention of it.
A natural question arises: what facts indicate the existence of back radiation at all? Let's start with the simplest - registration of the infrared spectrum of the substance. Molecules of the substance do not transmit infrared radiation in certain intervals of wavelengths (frequencies) for each substance. If a molecule
has absorbed photons and emits them again, then the emitted radiation should go in all directions: to the walls of the cell, back to the radiation source and, most importantly, to the sensor that perceives the radiation. Since the molecule emits at the same frequency as it absorbs, then some of the emitted photons reach the sensor and thereby neutralizes the registration of absorption. It turns out that in the case of back radiation, we would not be able to register the infrared spectra of various compounds at all.
The absorption and emission of energy by molecules of various substances in the infrared region of the spectrum is associated with molecular vibrations. There are different types of vibrations and all of them are caused by the movement of electrons (more precisely, by a change in the density of the electron cloud) that bind atoms in a molecule. The frequencies of molecular vibrations can be calculated based on data on the composition and structure of molecules: the masses of atoms, the values of the length and energy of bonds, and the angles of bonds (see, for example, [8]). The position of the absorption bands on the frequency axis in infrared spectra corresponds to the results of calculations, from which it follows that molecular vibrations are determined by the structure of the molecule, and not by the effect of an external electromagnetic field. The relationship between the frequency (ν) and energy of radiation (E) is determined by Planck's equation E = hν and, therefore, each molecular vibration corresponds to a certain change in energy. It follows that a molecule at a lower energy level can accept from an external field a photon with the energy necessary for the transition to an upper level. Since the values of the energy of the lower and upper levels are determined by the structure of the molecule, this molecule cannot accept any additional energy to change the kinetic energy of the motion of the entire molecule in space, which would change the temperature of the substance.
When a molecule reverts to a lower vibrational energy level, it is caused by a regular change in the density of the electron cloud, rather than by the emission of excess energy (which the molecule does not possess) into the environment. Thus, "greenhouse gases" do not absorb additional thermal energy due to their ability to block IR radiation, and therefore cannot emit energy that they do not have back.
3.6. The role of non-greenhouse gases in heat absorption by the
atmosphere
The assertion that the heating of the earth's surface and troposphere is “caused by the presence of carbon dioxide, methane, and certain other gases in the air” [1]. essentially excludes the role of the main components of the atmospherenitrogen and oxygen - in this process. This, of course, is сonsistent with the idea that heating is caused by the absorption of infrared radiation, but does not explain the fact that in reality we feel the heating and cooling of the air as a whole.
Some authors try to explain this by saying that greenhouse gas molecules transfer the energy they absorb to other molecules as a result of collisions. There is no point in discussing the correctness of this idea, since it is refuted by a simple experiment: pure "non-greenhouse" gas (nitrogen, oxygen, argon) heats up in a vessel under the action of sunlight in the same way as "greenhouse" carbon dioxide under the same conditions. The small difference in the observed temperatures is due to the heat capacity and thermal conductivity of the gases being studied.
In 2015, B.D. McDonald suggested that "the non-greenhouse” gases nitrogen and oxygen are essentially indistinguishable from greenhouse gases, since they have vibrational modes at 1556 and 2330 cm -1 respectively, in the IR region of the spectrum and are also observed by Raman spectroscopy [9]. Considering that Raman scattering (inelastic scattering) of photons is very weak, there is no reason to believe that it can somehow influence the kinetic energy of the motion of molecules, i.e. the change in gas temperature. It is unclear what could serve as a source of radiation in natural conditions that causes inelastic scattering of photons by gas molecules. Based on this, one cannot agree that the fact of observing Raman spectra for nitrogen and oxygen proves their role in the greenhouse effect.
However, the author's idea is that “all substances have thermal absorption properties, as measured by their respective heat capacities” [9] seems absolutely correct. Simply to confirm this, we must abandon the idea of the earth's radiation as the only source of atmospheric heating and recognize the leading role of thermal conductivity and convection in this process.
4. Сonclusion
The greenhouse effect theory is based on a number of postulates that seem
obvious to supporters but lack proof.
The postulate that the increasing concentration of greenhouse gases in the atmosphere is the cause of the Earth's warming has not been confirmed by direct physical experiment. The parallelism between the concentration of these gases in the atmosphere and the average global temperature does not prove a causeand-effect relationship.
The assertion that the Earth emits into space the same amount of radiant energy that it receives from the Sun is incorrect. It does not take into account for irreversible energy consumption in phase transitions (melting of ice, evaporation of water), the absorption of solar energy by biomass, and the transformation of part of the radiation energy into mechanical energy of wind and waves.
The basic postulate of the greenhouse effect theory, that infrared terrestial radiation absorbed by greenhouse gases leads to warming of the atmosphere, is not confirmed experimentally or theoretically. There is not a single physical experiment proving that the passage of infrared radiation of a certain frequency through a substance is accompanied by an increase in the temperature of the substance. According to the molecular-kinetic theory, a gas's temperature change is caused by a change in its molecules' kinetic energy, while the absorption of infrared radiation only changes the molecules' vibrational energy level within a strictly defined interval. Infrared radiation absorption does not give the molecule any additional energy.
As a result, we can conclude that the basic postulates of the greenhouse effect theory are unsupported by facts and contradict basic physical concepts.
References
1. https://www.britannica.com/science/greenhouse-effect
2. Climate Change 2007: Working Group I: Physical Science Basis. Frequently Asked Questions 1.3. What is the Greenhouse Effect?
https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-3.html
3. A. Ollila. The Greenhouse Effect Definition. - Phys. Sci. Inter. Journal, 22(5), 1-5, 2019.
https://www.academia.edu/53442072/The_Greenhouse_Effect_Definitio n?email_work_card=thumbnail
4. Microsoft Word, Lecture 5, Solar Radiation, Part 1, Principles, 2014. https://nature.berkeley.edu/biometlab/espm129/notes/Lecture_5_Solar _Radiation_Part_1_Principles_Notes_2014%20.pdf
5. Greenhouse Gas Protocol, p.3/ https://ghgprotocol.org/sites/default/files/ghgp/Global-WarmingPotential-Values%20%28Feb%2016%202016%29_1.pdf
6. United State Environment Protection Agency. Understanding of Global Warming Potentials. https://www.epa.gov/ghgemissions/understandingglobal-warming-potentials
7. The Earth-Atmosphere Energy Balance -NOAA, June 6, 2023. https://www.noaa/gov/jetsream/atmosphere/energy
8. Tables of molecular vibrational frequencies. Journal of Physical and Chemical Reference Data 7, No. 4, 1323-1442 (1978). https://srd.nist.gov/jpcrdreprint/1.555587.pdf
9. Blair D. Macdonald. Reinterpreting and Augmenting John Tyndall’s 1859 Greenhouse Gas Experiment with Thermoelectric Theory and Raman Spectroscopy. 2015.
https://www.academia.edu/101035579/Reinterpreting_and_Augmenting _John_Tyndall_s_1859_Greenhouse_Gas_Experiment_with_Thermoele ctric_Theory_and_Raman_Spectroscopy