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Reflections on the Greenhouse Effect

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The greenhouse effect phenomenon, as described in meteorology books, is not only questionable, but also defies the laws of thermodynamics. This phenomenon is not described in physics books. The classic version compares it to that which occurs in greenhouses, where solar radiation passes through the glass panels and warms the ground and the air inside. The thermal infrared radiation (IR) emitted inside the greenhouse is unable to pass through the glass, which is opaque to IR and absorbs it (glass absorbs wavelengths greater than 2.8 µm), preventing it from escaping to the environment outside the greenhouse. This phenomenon would be responsible for increasing its temperature, and in principle, the same thing is said to occur in the Earth’s atmosphere. As solar radiation hits the atmosphere, some of it (30%) is reflected back to the outer space by clouds, air molecules and the Earth’s own surface, but a good portion crosses the atmosphere and is absorbed by the Earth’s surface, which warms up.

Once heated, the Earth’s surface emits IR radiation, which in turn would be absorbed by gases that are minority components of the atmosphere such as water vapor, carbon dioxide (CO2) and methane (CH4), the so-called greenhouse gases (GHG) which are said to act similarly to glass. The GHG would emit absorbed IR radiation in all directions, including back to the surface. This would explain the fact that the air adjacent to the surface is warmer than in the upper layers of the atmosphere. In principle, the higher the concentration of GHG, the greater would be the absorption of radiation by the atmosphere and emission to the surface, and the warmer the planet would be. In other words, a higher injection of CO2 and CH4 into the atmosphere would tend to intensify the greenhouse effect.

Joseph Fourier
Joseph Fourier
Svante Arrhenius
Svante Arrhenius

The “heated greenhouse” phenomenon was first mentioned in the literature by mathematician Joseph Fourier in 1826.In 1859, John Tyndall discovered that gases such as water vapor, CO2, and CH4 absorbed IR radiation. In 1896, the chemist Svante Arrhenius stated that in his calculations, if the concentration of CO2 were to double, the global temperature would increase from 5° C to 6° C. Arrhenius did not even have a calculator,  but in order to reach the same figures, the Intergovernmental Panel on Climate Change (IPCC) needed billions of dollars to run complex climate models that run on supercomputers.

In 1909, Robert W. Wood built two greenhouse models, one of glass and the other of quartz, which does not absorb IR radiation.  He demonstrated that the final temperatures of the two were similar. In other words, the greenhouse kept warm not because of the property of glass to absorb IR radiation, but rather because the air, heated and less dense, was confined inside the greenhouse and unable to mix or rise (convection) and thus give way to colder air coming from other atmospheric layers, as happens in the free atmosphere. Therefore, absorption by the GHG would not be the main mechanism heating the air near the surface. However, because the weather was very cold back then, the subject was cast aside. It was only in 1938 that a technician in steam machines from British Electric, Guy S. Callendar, wrote an article associating the temperature increase observed between 1925 and 1937 to CO2 emissions due to the increase in thermoelectric power generation. At the time he was largely refuted by the “gurus” of climatology, but he did not give up.

Today we know that the increase in temperature between 1925 and 1946 was due to an increase in solar activity, greater transparency in the atmosphere, and higher frequency of El Niño events, and therefore it was natural! In 1956, Charles Keeling modified a gas chromatograph in order to measure CO2 using a wavelength of IR radiation that is absorbed by it. He started to measure CO2 concentration by IR absorption, and not by chemical analysis as had been done until then. Keeling joined Callendar to argue that CO2 caused global warming. No one cared much, however, because it occurred during a global cooling between 1946 and 1976, even though CO2 emissions were growing rapidly due to increased post-war industrial activity.

The greenhouse effect phenomenon, as described in meteorology books, is not only questionable, but also defies the laws of thermodynamics. This phenomenon is not described in physics books. The classic version compares it to that which occurs in greenhouses, where solar radiation passes through the glass panels and warms the ground and the air inside. The thermal infrared radiation (IR) emitted inside the greenhouse is unable to pass through the glass, which is opaque to IR and absorbs it (glass absorbs wavelengths greater than 2.8 µm), preventing it from escaping to the environment outside the greenhouse. This phenomenon would be responsible for increasing its temperature, and in principle, the same thing is said to occur in the Earth’s atmosphere. As solar radiation hits the atmosphere, some of it (30%) is reflected back to the outer space by clouds, air molecules and the Earth’s own surface, but a good portion crosses the atmosphere and is absorbed by the Earth’s surface, which warms up.

Once heated, the Earth’s surface emits IR radiation, which in turn would be absorbed by gases that are minority components of the atmosphere such as water vapor, carbon dioxide (CO2) and methane (CH4), the so-called greenhouse gases (GHG) which are said to act similarly to glass. The GHG would emit absorbed IR radiation in all directions, including back to the surface. This would explain the fact that the air adjacent to the surface is warmer than in the upper layers of the atmosphere. In principle, the higher the concentration of GHG, the greater would be the absorption of radiation by the atmosphere and emission to the surface, and the warmer the planet would be. In other words, a higher injection of CO2 and CH4 into the atmosphere would tend to intensify the greenhouse effect.

The “heated greenhouse” phenomenon was first mentioned in the literature by mathematician Joseph Fourier in 1826.In 1859, John Tyndall discovered that gases such as water vapor, CO2, and CH4 absorbed IR radiation. In 1896, the chemist Svante Arrhenius stated that in his calculations, if the concentration of CO2 were to double, the global temperature would increase from 5° C to 6° C. Arrhenius did not even have a calculator, but in order to reach the same figures, the Intergovernmental Panel on Climate Change (IPCC) needed billions of dollars to run complex climate models that run on supercomputers.

In 1909, Robert W. Wood built two greenhouse models, one of glass and the other of quartz, which does not absorb IR radiation. He demonstrated that the final temperatures of the two were similar. In other words, the greenhouse kept warm not because of the property of glass to absorb IR radiation, but rather because the air, heated and less dense, was confined inside the greenhouse and unable to mix or rise (convection) and thus give way to colder air coming from other atmospheric layers, as happens in the free atmosphere. Therefore, absorption by the GHG would not be the main mechanism heating the air near the surface. However, because the weather was very cold back then, the subject was cast aside.. It was only in 1938 that a technician in steam machines from British Electric, Guy S. Callendar, wrote an article associating the temperature increase observed between 1925 and 1937 to CO2 emissions due to the increase in thermoelectric power generation. At the time he was largely refuted by the “gurus” of climatology, but he did not give up.

CHARLES KEELING

Today we  know that the increase in temperature between 1925 and 1946 was due to an increase in solar activity, greater transparency in the atmosphere, and higher frequency of El Niño events, and therefore it was natural! In 1956, Charles Keeling modified a gas chromatograph in order to measure CO2 using a wavelength of IR radiation that is absorbed by it. He started to measure CO2 concentration by IR absorption, and not by chemical analysis as had been done until then. Keeling joined Callendar to argue that CO2 caused  global warming. No one cared much, however, because it occurred during a global cooling between 1946 and 1976, even though CO2 emissions were growing rapidly due to increased post-war industrial activity.

JAMES HANSEN

From 1977 onwards, the climate began to warm up again, and in 1988, Dr. James Hansen of NASA’s Goddard Institute for Space Studies testified before the American Congress in which he stated that warming was due to the increase in man-made CO2 through the burning of petroleum, coal, and natural gas. The IPCC was created that same year and global hysteria ensued. As can be seen, the greenhouse effect has never been proven, nor was its existence demonstrated. On the contrary, 100 years ago, Robert W. Wood had already demonstrated that his concept is false. However, a lie repeated countless times becomes true in people’s eyes.

According to Stefan-Boltzmann’s law, by measuring IR emissions from the Earth to outer space with sensors on board space platforms, one finds an effective blackbody temperature of 255 kelvin (-18° C). The average temperature of the air at the surface is about 288 kelvin (15° C). Here it is said that, “the greenhouse effect increases the temperature on earth by 33° C (the difference between 288 and 255) and that, if it did not exist, the surface temperature would be -18° C”! This assertion is false because if there were no atmosphere, there would be no clouds, for example, which are responsible for half of the planetary albedo. Thus, the solar radiation flow would be 15% higher and the planetary temperature would be 268 kelvin (-5º C).

However, the questionable mechanism is the process of absorption and emission of IR by the GHG. If CO2 is treated as a blackbody, as it efficiently absorbs IR radiation in 15 microns, its emission, which is at its maximum in this wavelength (Kirchhoff’s law), would correspond to a temperature of approximately 193 kelvin (-80°) according to the law of Wien. Would a cold body (CO2 in the air) warm a hot body (the surface)? This certainly violates the second law of thermodynamics! The theory states that GHG absorb IR by rotating their molecules and vibrating their atoms only in IR frequencies, causing their molecules to go into resonance. Rotation and vibration are mechanical movements and generate kinetic energy, which is dissipated in the form of heat by colliding with the more than 2,600 molecules of the main gases in the atmosphere, nitrogen (78%), oxygen (21%), and argon (0.9%), which involve each CO2 molecule.

It is known that the collisional deactivation of the vibrationally excited CO2 molecule is about 10,000 times faster than its radiactive decay. Therefore, if CO2 loses its IR, which is absorbed by collisions with other molecules, it is unable to emit IR. And given its minimal presence in the atmosphere (0.039%), its contribution to heating the air by collision is negligible! Accordingly, if all CO2 was removed from the atmosphere the air temperature variation could not be detected by the current instruments. The molecules of the gaseous mixture called “air” (matter) are heated when provided with heat. It is more acceptable, then, that temperatures closer to the surface are higher due to air contact with the hot surface (“hot plate” heat conduction) and to atmospheric pressure (air weight). In other words, the atmospheric mass subjected to the acceleration of gravity (weight ÷ area = pressure) is what keeps the air confined to the surface and warms it up by compression (ideal gas law = temperature proportional to pressure) and the sensible heat provided by the surface. When the air warms up its density decreases so that if the buoyancy to which it is subjected exceeds its weight (1.20 kg/m3 at 20°C), it is forced to rise (convection = heat transport by means of the vertical transport of the air mass) and is replaced by colder air from its surroundings and from upper layers.

Therefore, the most relevant physical process for heating the air is heat conduction from the hot surface, followed by convection. In addition, the air is heated by releasing latent heat (wet convection = heat released into the atmosphere when the water vapor liquefies, forming clouds and rain) and by a small percentage of direct absorption of solar radiation. The emission of IR radiation plays a secondary role in controlling the temperature of the air near the surface. The second law of thermodynamics states that heat flows from a hot to a cold body. Since the air layers above the surface are cooler than it is, the energy (heat) cannot flow from the atmosphere to the surface and heat it.

By absorbing IR radiation, the air layers (matter) function as an imperfect thermal insulator that at best slows down the cooling rate of the surface. Since the GHG, and particularly CO2, are minority constituents, they contribute very little to the total atmospheric gas mass, and consequently, to their cooling rate. In other words, if the GHG did not exist the air temperature near the surface would reach values similar to those currently occurring. Therefore, if the CO2 concentration due to anthropic emissions doubled from 0.039% to 0.078%, the increase in its molecular mass would be insignificant, and its contribution to air temperature would be negligible.

In the tropics, the air temperature near the surface depends mostly on cloud cover and rain. The hydrological cycle is the surface’s “thermostat”. When the weather is cloudy and rainy, the temperature is low. That is because the cloud cover works like a parasol, reflecting solar radiation back into the outer space. Simultaneously, rainwater is colder and its evaporation steals heat from the surface, cooling the air. The opposite happens when there are no clouds or rain, as more solar radiation enters the system, warms the surface, and since there is no water to evaporate, this heat is used almost exclusively to heat the air (sensible heat).

Furthermore, if the air is humid shortly after a summer rain, the thermal sensation is intensified because the high humidity of the air hampers skin sweating, which is the physiological mechanism that regulates the temperature in humans. During the dry period, air descends over the region causing high atmospheric pressure, clear skies, heat inversion, and hindering the rise of heated air, reducing cloud cover. This makes the surface and the air in contact with it reach high temperatures. In a city, due to the urban covering of the soil, there is no rainwater to evaporate and all the heat of the sun is used to heat the air. As cities grew and the population gathered in them, the urban population has the impression that the world is warming up. Installed in a city, a thermometer corroborates this perception as it starts to show increasingly high temperatures to the degree the urbanized area grows with time—the so-called “urban island heat effect”.

In other words, the thermal sensation felt by human beings comes from local rather than global atmospheric conditions. The methodology to calculate the “global average temperature” is unknown, and the locations of the series of temperatures used by the IPCC are kept secret! Now, if those temperatures were measured by using “cherry-picked” thermometers, particularly those installed in large urban centers where the longest series of measurements are located, with data contaminated by the urban island heat effect, it is no surprise that the decade of 2000 has been considered the “hottest” in the last 650 years! In reality, there is no way to calculate “a global average temperature” and adopt it as a measure of global climatic variability. A more appropriate measure of this variability would be an estimation of the temporal variation of the heat stored in the oceans. In conclusion, as described in the literature, the greenhouse effect has never been demonstrated and it is difficult to accept that the alleged emission process by the GHG, particularly CO2, is the main cause of high air temperatures close to the surface.

Atmospheric air mass only slows down the loss of IR emitted by the surface to outer space. The masses of CO2 and CH4 in the atmosphere are very small, and their contribution to air heating by IR absorption is irrelevant. Statements like “We have to prevent the temperature from increasing by more than 2° C by maintaining CO2 concentration below 460 ppmv” make no sense from the standpoint of Physics. This calculation comes from a great simplification of the GHG absorption equation, “adjusted” to reproduce the temperature increase with the variation of the CO2 concentration observed. This equation has no scientific basis whatsoever. Therefore, the reduction of carbon emissions into the atmosphere will have no effect on the climate trend, for CO2 does not control the global climate. And the trend for the next 20 years is global cooling even if the concentration of CO2 continues to increase. Considering that 80% of the global energy matrix depends on fossil fuels, imposing a reduction of carbon emissions will in fact affect the development of poor countries and particularly Brazil, increasing social inequalities on the planet.

Atmospheric air mass only slows down the loss of IR emitted by the surface to outer space. The masses of CO2 and CH4 in the atmosphere are very small, and their contribution to the warming of the air by IR absorption is irrelevant. Statements like “We have to prevent the temperature from increasing by more than 2° C by maintaining CO2 concentration below 460 ppmv” make no sense from the standpoint of Physics. This calculation comes from a great simplification of the GHG absorption equation, “adjusted” to reproduce the temperature increase with the variation of the CO2 concentration observed. This equation has no scientific basis whatsoever. Therefore, the reduction of carbon emissions into the atmosphere will have no effect on the climate trend, for CO2 does not control the global climate. And the trend for the next 20 years is global cooling even if the concentration of CO2 continues to increase. Considering that 80% of the global energy matrix depends on fossil fuels, imposing a reduction of carbon emissions will in fact affect the development of poor countries and particularly Brazil, increasing social inequalities on the planet.

Bibliography

  • Calendar, G.S., The artificial production of Carbon Dioxide and its influence on climate. Quart. Jour. Roy. Met. Soc. 64, p: 223-240, 1938.
  • Fleagle, R.G. e J.A.Businger. An Introduction to Atmospheric Physics. Academic Press, p.432, New York, NY, 1980.
  • Callendar, G. S. “Can Carbon Dioxide Influence Climate?” Weather 4, 310–314, 1949.
  • Wood, R.W. “Note on the theory of the greenhouse effect,” Philosophical Magazine, vol. 17, p.319-320, ou em http://sci.tech-archive.net/pdf/Archive/sci.physics/2008-04/msg00498.pdf, 1909
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