WHAT GASES CAUSE THE ATMOSPHERE TO OVERHEAT? - SCIENCE - 2025

The gases that cause the atmosphere to overheat are those that absorb and emit infrared radiation. Likewise, gases that damage the ozone layer contribute to overheating, because they facilitate greater penetration of ultraviolet radiation.

Global warming is the increase in the average temperature in the terrestrial biosphere that occurs due to the greenhouse effect. This effect is a natural phenomenon that consists of blocking the exit of terrestrial heat (infrared radiation) towards outer space.

Gases that cause overheating. Source: A loose necktie

This blockage is exerted by some of the gases that naturally make up the earth's atmosphere, such as water vapor and CO2. This is a phenomenon that occurs naturally and allows the planet to have a biologically appropriate temperature.

How do gases heat the Earth?

The fundamental source of energy that warms the Earth is solar radiation, particularly ultraviolet radiation. It is partially filtered by the ozone layer (O3) in the stratosphere.

The ultraviolet radiation (short wave) that manages to penetrate heats the earth's surface and its heat is emitted into space as infrared radiation (long wave). However, there is a human influence on the process due to the artificial emission of greenhouse gases.

These gases absorb and emit heat or destroy ozone that regulates the entry of ultraviolet radiation. The gases that contribute to the greenhouse effect, either naturally or by human influence, are called Greenhouse Gases (GHG).

At the global level, special attention is paid to global warming and the destruction of the ozone layer. The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty that entered into force in 1989 and regulates the use of these gases.

This protocol was ratified by 65 countries with the Kigali amendment of January 1, 2019. For its part, the Kyoto Protocol addresses issues concerning global warming.

In the Kyoto Protocol six greenhouse gases are contemplated which are carbon dioxide, methane, nitrous oxide, hydrofluorocarbon, perfluorinated hydrocarbon and sulfur hexafluoride.

To evaluate a gas that produces overheating, its useful life and its global warming potential (GWP) are considered. The GWP compares the amount of heat trapped by a gas with the heat trapped by CO2, the GWP of which is standardized to 1.

Main gases cause the atmosphere to overheat

Water steam

Water vapor is a natural and vital component of the Earth's atmosphere and plays a very important role in the greenhouse effect due to its ability to absorb heat. In addition, water in liquid and solid state reflects solar energy, cooling the Earth.

Carbon dioxide (CO2)

Carbon dioxide is the main greenhouse gas, being responsible for more than 80% of the increase in this phenomenon. CO2 levels have risen alarmingly due to industrial and transportation activity.

According to some estimates, before the Industrial Revolution, the atmospheric concentration of CO2 reached about 280 ppm (parts per million) and in 1998 it reached 365 ppm. This represents a rate of increase of 1.5 ppm per year and a 31% increase from the 1750 levels.

CO2 concentration. Source: Hannes Grobe 21:17, 5 November 2006 (UTC)

By determining the isotopic composition of current atmospheric CO2, it has been shown that the increase comes from the burning of fossil fuels and deforestation. CO2 works by absorbing and emitting infrared radiation and has a useful life of 5 to 200 years.

Methane (CH

Methane is the second greenhouse gas, contributing about 17% of the warming, through the absorption and radiation of heat. Although much of this gas occurs naturally, mainly in swamps, there is an important human contribution (about 50%).

Methane concentration. Source: Methane-global-average-2006.jpg: NOAAderivative work: Ortisa

Approximately 60% of the methane that currently exists in the atmosphere is the product of human (anthropic) activities. Among the main anthropic sources are ruminant livestock, rice cultivation, the exploitation of fossil fuels and the combustion of biomass.

The estimated levels of this gas before the Industrial Era are 700 ppb (parts per billion) and for 1998 it reached 1,745 ppb, which represents an increase of 149%. However, methane has a useful life in the lower atmosphere, reaching only 12 years.

Nitrogen oxides (NOx)

NOx, especially nitrous oxide, contribute to the destruction of stratospheric ozone by increasing the amount of ultraviolet radiation that penetrates the Earth. These gases originate from the industrial production of nitric acid, adipic acid and the use of fertilizers.

Nitrous oxide (N2O) had an atmospheric concentration of 270 ppb before the Industrial Era, to then reach 314 ppb in 1998. This represents a 16% increase in its concentration, and it has a useful life of 114 years which makes it very problematic.

Hydrofluorocarbons (HFCs)

They are gases used in various industrial applications, replacing the CFCs limited by the Montreal agreement. However, HFCs also affect the ozone layer and have a high active permanence in the atmosphere (up to 260 years).

These gases did not exist in the atmosphere, they were introduced by humans and in the case of HFC-23 it reaches a concentration of 14 ppt (parts per trillion).

Perfluorinated hydrocarbon (PFC)

PFCs are produced in incineration facilities for the aluminum smelting process. Like HFCs, they have a high permanence in the atmosphere and affect the integrity of the stratospheric ozone layer.

Sulfur hexafluoride (SF6)

This is another gas whose overheating effect goes through the destruction of the ozone layer. It is used in high voltage equipment and in the production of magnesium, and has a high permanence in the atmosphere.

Chlorofluorocarbons (CFCs)

CFC is a powerful greenhouse gas that damages stratospheric ozone and is regulated under the Montreal Protocol. However, in some countries it is still used, such is the case of China.

Damage to the ozone layer is caused by chlorine atoms dissociating when hit by ultraviolet radiation.

The main chlorofluorocarbons are CFC-11, CFC-12, CFC-13, CFC-113, CFC-114 and CFC-115. These gases did not exist in the atmosphere, but by 1998 CFC-11 already reached 268 ppt, with a useful life of 45 years.

Methylchloroform or trichloroethane (CH3CCL3)

It is a particular type of CFC, used as a solvent and in cleaning metals. When decomposing, it emits chloride gases, whose chlorine atoms contribute to the destruction of the ozone layer.

Tropospheric ozone (O3)

The tropospheric O3 is the ozone that is formed at ground level, between the surface and 18 km high. Although stratospheric ozone contributes to reducing global overheating by reducing the entry of ultraviolet radiation, tropospheric ozone generates warming.

Smog in Harbin (China). Source: Fredrik Rubensson

It has been argued that the effect of tropospheric ozone is contradictory. On the one hand it generates a superficial warming of the earth, but at the same time it eliminates other greenhouse gases.

In any case, O3 is a toxic gas that causes lung damage, in addition to deteriorating various materials.

Chlorodifluoromethane (HCFC-22)

It is called R-22, a colorless gas and until recently the most used in refrigeration equipment. However, today it is banned in much of the world due to its negative effect on the ozone layer.

Carbon chloride or carbon tetrachloride (CCl4)

It is an organochlorine that is now banned in many places due to its toxicity, but it was widely used as a refrigerant, extinguishing agent, degreaser and pesticide. When this compound degrades, it generates derivative substances that affect the ozone layer.

Tetrafluoromethane or perfluoromethane (CF4)

It is a gas known as R-14 and used as a refrigerant, but it has a high capacity to absorb and emit ultraviolet energy. It has a lifetime in the atmosphere of more than 50,000 years and a global warming potential of 6,500.

According to Guinness World Records, tetrafluoromethane is the most persistent greenhouse gas, although its low proportion in the atmosphere restricts its effect.

Hexafluoroethane (C2F6)

It is used in refrigerants and in the production of aluminum, since thanks to the high energy of its carbon-fluorine bonds it is very stable. This gives it a long service life of at least 500 years.

Likewise, it has a high potential for absorbing infrared radiation, making it a problem for global temperatures. Hexafluoroethane is on the list of greenhouse gases from the Intergovernmental Panel on Climate Change (IPCC).

Sulfur hexafluoride (SF6)

It is a non-toxic gas, five times heavier than air, with a GWP index of 176 (20,000 times more than CO2). On the other hand, it has a useful life of 3,200 years, although because it is so dense it does not rise to the upper layers of the atmosphere.

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