Greenhouse Gas Definition, Sources, Emission, and Effects Explained
This article outlines the definition, sources, emission and typical effects of a Greenhouse Gas on the environment. It includes the following;
2). Why Greenhouse Gases are Important
3). Greenhouse Gas Names: Examples of Greenhouse Gases
4). Greenhouse Gas Emissions Statistics
Greenhouse Gas Definition: What is the Meaning of the term; “Greenhouse Gas”?
A Greenhouse Gas, is simply any gas which is able to absorb infrared radiation that is emitted from the Earth’s surface, and reflect it back toward the Earth as heat energy .
Through this mechanism, the greenhouse gas affects the environment on Earth, especially in terms of atmospheric and climatic factors.
Greenhouse Gas Meaning
As earlier said, a Greenhouse Gas is a gas which has the capability of absorbing or trapping heat energy that is emitted from the Earth’s surface, and re-emitting it back to the Earth.
This heat energy is usually retained in the lower atmosphere. Some of it is reflected upon the land, and into water bodies like oceans, streams, lakes and rivers.
Why Greenhouse Gases are Important
By trapping, absorbing and re-emitting radiant energy and heat that was initially reflected from the Earth toward the atmosphere, greenhouse gases play a very significant role in the process of energy distribution on Earth.
Greenhouse gases are responsible for keeping the Earth at temperatures which support the survival of living organisms.
Although they may have negative effects by leading to processes like Global Warming and the Greenhouse Effect, these gases also prevent the Earth’s temperature from being too low to support life .
Because greenhouse gases can absorb infrared radiation, they significantly reduce the amount of heat from solar radiation, that is able to return to the upper atmosphere.
At the same time, they easily allow more solar radiation to reach the Earth’s surface.
A number of notable effects of greenhouse gases are discussed in the following sections of this article.
Greenhouse Gas Names: Examples of Greenhouse Gases
We cannot proceed meaningfully without mentioning some examples of greenhouse gases. The main examples of greenhouse gases are;
1). Carbon dioxide (CO2)
2). Methane (CH4)
3). Nitrous Oxide (N2O)
4). Fluorinated Gases
Carbon dioxide (CO2)
Carbon dioxide, (CO2) is a colorless, acidic gas which has a sour taste and a faint sharp odor . This gas is a very important cause of global warming. However, carbon dioxide can be found in the atmosphere, naturally. It makes up about 0.04% of the natural composition of air.
CO2 is also naturally produced in the process of decomposition of organic materials, in respiration of living organisms, in fermentation of carbohydrates, and in combustion.
The gas acts as a greenhouse gas, by absorbing a portion of the radiant energy from the sun (and from the Earth’s surface) and preventing it from being lost in the upper atmosphere.
By retaining the heat energy from the sun, CO2 contributes to the greenhouse effect. It is industrially recovered from lime kilns and flue gases, among others.
Carbon dioxide may enter the atmosphere as a result of the combustion of fossil fuels, and other forms of biomass. It may also be removed from the atmosphere in the process of carbon sequestration .
Methane refers to an odorless, and colorless gas which is naturally-occurring and may also be produced from some human activities.
It is a highly potent greenhouse gas and has the chemical formula CH4.
Methane has a lower density than air, and is slightly soluble in water. However, in air it burns with a pale flame to form water vapor and carbon dioxide. It is a generally stable gas, but when mixed with air, is usually explosive. It is the sole cause of most mine explosions.
Methane is emitted in the production and usage of fossil fuels. It may also be emitted from livestock farming and other agricultural processes, as well as from the decomposition of municipal waste material in landfills and other dump sites.
Nitrous oxide (N2O)
N2O is one of the major greenhouse gases. It has been found to be very instrumental in causing climate change.
While N2O as a gas is produced naturally, in soils and oceans, it has also been found to be a product of human activity as well.
Concentrations of N2O in the atmosphere have risen in recent time. Between 1940 and 2018, the gas has increased from approximately 290 parts per billion to 331:parts per billion.
A significant proportion of N2O emissions are produced from agricultural processes. These are mostly due to the activities of microbes in soils. These microbes break down manure and nitrogen-based fertilizers in the soil, releasing nitrous oxide gas. The process is known as Denitrification.
Asides agriculture. N2O gas can be produced from waste water, chemical manufacturing processes, and fossil fuel combustion.
N20 is up to 300 times as potent as carbon dioxide (CO2). It also has a typical lifetime of 116±9 years in the atmosphere.
When N2O comes in contact with ozone molecules in the atmosphere, it destroys them, leading to ozone depletion on a large scale.
As a greenhouse gas, N₂O has 300 times the warming potential of carbon dioxide (CO₂) and stays in the atmosphere for an average 116 years .
It’s the third most important greenhouse gas after CO₂ (which lasts up to thousands of years in the atmosphere) and methane.
N2O is currently not banned under the 1987 United Nations Montreal Protocol. This is partly because it listed as an essential medicine by the World Health Organization (WHO 2019).
It is however restricted by the Council of the London Borough of Lambeth (UK), and there have been measures to reduce its production in many countries
Fluorinated gases (or F-gases) refer to a group of anthropogenic gases which are utilized typically in different industrial processes. In order to mitigate climate change, regulatory policies have been developed in the EU and other regions.
Although Fluorinated gases are effective greenhouse gases, they do not generally destroy ozone molecules or cause ozone layer depletion.
However, they are responsible for contributing significantly to the greenhouse effect. and global warming. Fluorinated gases are known to have a potency of about 23,000 times that of carbon dioxide (CO2) with respect to causing global warming .
Fluorinated gases include perfluorocarbons, hydrofluorocarbons, nitrogen trifluoride and sulfur hexafluoride. These gases are often used in place of other chemicals and gases like which deplete the ozone layer in the stratosphere.
Hydrofluorocarbons (HFCs) can be considered to be the most important group of fluorinated gases with respect to climate change and the greenhouse effect.
They are basically a group of highly active greenhouse gases which are industrially manufactured for various purposes. These purposes include air conditioning, aerosols, foam blowing, refrigeration. solvents and fire protection.
In contrast to other greenhouse gases, hydrofluorocarbons are not usually produced as waste products.
They are generally produced as a substitute to ozone depleting substances, most of which have been restricted by the UN Montreal Protocol. This is because they do not actively contribute to ozone layer depletion.
The use of hydrofluorocarbons has increased greatly over the years, and this has potential effects on climate change and global warming. Also, hydrofluorocarbons comprise approximately 1-3% of the overall greenhouse emissions globally. . It is estimated that this will increase to about 7% in the coming years if allowed to progress at the current rate.
Perfluorocarbons refer to a group of man-made chemical compounds which comprise solely of fluorine and carbon .
They are very active greenhouse gases, and are also used in place of ozone depleting substances, due to the fact that they do not destroy ozone molecules. Industrially, perfluorocarbons are used to manufacture semiconductor materials. Other uses include as refrigerants, and solvents.
Sulfur Hexafluoride (SF6) is an odorless, colorless gas which is synthetic in nature . it is used as an insulating material in electrical systems, for preventing electrical accidents and fore outbreaks .
In its pure state, SF6 occurs as a non-flammable and inert gas which is denser than air. It is capable of accumulating in tunnels, trenches and pits. Sulfur hexafluoride may cause asphyxiation when present in air, in volumes of up to 19% .
Asides being the most potent greenhouse gas , SF6 has a long lifetime of up to 3,200 years in the atmosphere. This implies that even a relatively small volume of the gas can have significant impacts on the environment, leading to greenhouse effect, global warming and climate change.
Nitrogen tri-fluoride (NF3) is simply a chemical which is produced and used industrially. It is especially prominent in electronics manufacturing, including Liquid Crystal Display (LCD) panels, chemical lasers, semiconductors and solar panels .
The use of NF3 in industries is a potential problem to the environment. This is because this gas is several times more potent as a greenhouse agent, than carbon dioxide (CO2) and most other greenhouse gases.
The Greenhouse Gas (GHG) Protocol and the United Nations Framework Convention on Climate Change (UNFCCC), both classify NF3 as a contributive cause of climate change . This implies that it is used and produced with restrictions.
Another, highly significant example of a greenhouse gas which you would need to know, is ozone (O3).
Ozone may be categorized either as ground-level/surface/tropospheric ozone, or stratospheric ozone. We may also think of the two categories as man-made and naturally-occurring ozone.
Ground-level (or Surface) ozone is produced as produced from the reaction between Volatile Organic Compounds (VOCs), Carbon monoxide (CO), and Nitrous oxides (NOx) . The gas causes air pollution, which has negative impacts on human health.
Ground-level ozone is usually emitted from power plants, vehicles, refineries, industrial boilers and chemical manufacturing plants. It is usually more concentrated in urban areas, although it may still occur in rural areas. The average concentration of ground-level ozone in the atmosphere is 10ppb, although this concentration can reach levels of up to 70ppb .
Stratospheric Ozone may also be referred to as Natural Ozone. It occurs naturally in the stratosphere. While the low-level or tropospheric ozone is often called “bad ozone”, the stratospheric ozone is often called “good ozone”.
This is simply because; while the ground-level (tropospheric) ozone tends to cause health ailments and air pollution , the stratospheric ozone plays a more positive role.
The role of the stratospheric ozone is to protect the Earth from the Sun’s ultraviolet-B radiation (UV-B). It reduces the amount of UV-B radiation which reaches the Earth’s surface, and thereby protects plants and animals. Asides damaging plant cells and stunting their growth, UV-B radiation may cause cancer in humans .
Stratospheric ozone functions as a greenhouse gas, because it retains the heat energy of the UV-B radiation in the stratosphere. This heat energy increases the temperature of the atmosphere and the Earth’s surface.
Below is a table showing the differences between Tropospheric and Stratospheric Ozone;
|Tropospheric Ozone||Stratospheric Ozone|
|Occurs in the Troposphere, at 0-10km above sea level||Occurs in the Stratosphere, at 10-50km above sea level|
|Is produced mainly by man-made processes||Is naturally-occurring|
|Is usually referred to as “bad ozone”||Usually referred to as “good ozone”|
|Is toxic to living organisms||Is non-toxic|
|Is mainly concentrated in urban areas, as smog||Is evenly distributed over the Earth|
|Is not actively involved in the greenhouse effect, and global warming||Contributes to the greenhouse effect|
|Does not actively prevent ultraviolet radiation from reaching the Earth’s surface||Actively prevents harmful ultraviolet-B radiation from reaching the Earth’s surface|
Greenhouse Gases and their Sources- Greenhouse Gas Emissions by Source
The sources of greenhouse gas emissions are discussed as follows;
1). Cement Production
The manufacture of cement produces greenhouse gases, and contributes to the greenhouse effect.
Carbon dioxide is the main greenhouse gas which is produced as a result of cement production. It may be either generated as a direct product of the heating of calcium carbonate (CaCO3), or limestone, to produce clinker .
Alternatively, greenhouse gases like methane (CH4) and carbon dioxide (CO2) are produced from the exhausts of the engines used to drive the entire process of cement production.
Deforestation is a major contributor to the global carbon emission budget. This means that it also contributes to climate change on a global scale.
The effect of deforestation on the climate is mainly due to the fact that vegetation acts as a natural ‘carbon sink’ . Plants consume carbon dioxide and release oxygen in the process of photosynthesis, and this creates a healthy balance in the concentration of carbon dioxide in the atmosphere.
However, by removing trees in the process of deforestation, these carbon sinks are eliminated. The trees may also decompose, or be processed, or be used as biomass fuel. Such activities produce methane and carbon dioxide, which are greenhouse gases.
There have been so far, some important climate policies which have been developed to address the problem of deforestation. In general, deforestation is responsible for about 20% of the overall carbon emissions globally .
The United Nations Framework Convention on Climate Change (UNFCCC), at the 2005 Conference of the Parties (COP) in Montreal, developed an initiative for evaluating the effects of deforestation on climate change.
This initiative also includes schemes for implementing mitigation policies to reduce emissions as a result of deforestation, especially in developing nations.
3). Fossil Fuel Combustion
In this case, fossil fuels refer to flammable materials derived from the preservation and alteration of organic matter.
They include petroleum, coal and natural gas .
Coal refers to brown or black sedimentary material which is formed from vegetation and plant matter. The plant matter includes algae and remains of vegetation. These materials form coal after long periods (millions of years) of accumulation and burial.
Coal is categorized into different types, including lignite, bituminous coal, sub-bituminous coal and anthracite. These types differ in terms of their carbon content and degree of maturity. Coal is used in several developed and developing countries including the United States, India and China.
They are extracted by mining and make up about one-third of the total energy budget globally.
Coal produces approximately 40 percent of total carbon dioxide (CO2) emissions worldwide. There has been a decline in the use of coal in countries like the U.S, due to its negative impacts on the environment.
Oil, or Crude Oil, is mainly comprised of hydrogen and carbon, and occurs as a dark liquid. It may occur in various forms and my have varying properties.
Like coal, crude oil is formed from organic matter which has been buried for millions of years. This includes algae, plankton, and vegetation.
Crude oil is extracted by drilling onshore and offshore. It is presently the most relied-upon energy source globally. Major oil and gas producing countries include Russia, U.S, Nigeria, Qatar, and Saudi Arabia.
Approximately one-third of the overall carbon emissions worldwide is produced from petroleum. The problems of air pollution, greenhouse gas emission, global warming and climate change which result from petroleum extraction and usage are severe.
At the same time, the world remains dependent on crude oil and its products, including lubricants, asphalt, and plastics.
Natural Gas refers to an odorless gas which mainly comprises of methane. It is usually found occurring together with other fossil fuels like coal and crude oil. Like other fossil fuels, natural gas produces large volumes of carbon dioxide as well.
Fossil fuels are important because they account for up to 80% of the world’s energy sources . In both developed and developing countries, fossil fuels are used to provide heat and electricity for domestic, industrial and commercial processes.
Around the world, governments are actively working to reduce the production rate, of greenhouse gases. There have also been international agreements and protocols to address climate change and global warming as a result of greenhouse gas emissions.
An example of an protocol in this area is the Paris Agreement (2015). Such protocols are aimed at reducing the use of fossil fuels as energy sources. They propose that renewable energy technologies be used instead, such as solar, wind, hydro and wave energy.
While it is obvious that climate change affects agriculture, in reverse, agriculture also leads to climate change.
Currently, agriculture is responsible for up to 10% of the overall volume of greenhouse gas emissions. At the present rate, it is predicted that this percentage will rise even further.
In the U.S, the proportion of greenhouse emissions caused by agriculture is approximately 9-10 percent. This implies that agriculture contributes hugely to global warming and climate change.
The main greenhouse gases produced from agricultural practices include carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O).
In 2020, the US recorded a release of these agricultural greenhouse gases in the following proportions;
|Greenhouse Gas||Proportion (%)|
5). Semiconductor Manufacturing
Basically, semiconductor manufacturing is not one of the major sources of greenhouse gases. However, the process produces greenhouse gas emissions both indirectly and directly.
There are various avenues by which semiconductor manufacturing can produce greenhouse emissions. One of these is the use of Perfluorocarbons (PFCs) as cleaning/etching gases in the process of manufacturing semiconductor chips.
Additionally, greenhouse gases are emitted from the energy-generating plants which drive the process of semiconductor manufacturing.
Refrigerants like chlorofluorocarbons (CFCs) deplete the ozone layer. Other refrigerants like hydrofluorocarbons, act as highly effective greenhouse gases.
Hydrofluorocarbons (HFCs) are used commonly in Refrigeration and Air-Conditioning (RAC) systems. These gases actively absorb ultraviolet and infrared radiation, thereby contributing to the greenhouse effect.
7). Electricity Production and Transmission
The process of electricity generation and transmission, is single-handedly responsible for producing a large proportion of total greenhouse gas emissions.
This is because, electricity is produced chiefly from fossil fuels like petroleum, coal and natural gas .
The main greenhouse gas produced in relation to electricity transmission is carbon dioxide (CO2). Also, the amount of CO2 which is emitted is dependent on the type of fossil fuel used to generate electricity .
Percentage proportion of different fossil fuels used to produce electricity
Currently, fossil fuels utilized for electricity generation are in the following proportion;
|Fossil Fuel||Proportion (%) used in Electricity Generation|
The remaining percentage (31%) is constituted by nuclear and renewable energy sources.
Another greenhouse gas related to electricity is Sulfur hexafluoride (SF6). This gas is used as an insulator for electricity distribution and transmission equipment. As a result of this, regulations have been developed to check the use of this gas and reduce emissions.
Greenhouse Gases and the Greenhouse Effect
The greenhouse effect, as earlier stated, involves the increase in temperature of the lower atmosphere and Earth’s surface.
As we may predict, greenhouse gases are the sole cause of the greenhouse effect. The temperature rise occurs typically when these greenhouse gases absorb solar radiation that has been reflected from the Earth’s surface.
A small percentage of this reflected radiation usually escapes into space and the upper atmosphere. The percentage which is absorbed by greenhouse gases is what results in the thermal effect which is experienced on the Earth surface.
The thermal radiation, when absorbed, causes the temperature of the Earth’s surface to be consistently at about 33°C above what it would have been in the absence of the greenhouse effect.
The greenhouse effect is positive in the sense that it makes the Earth to be warm enough for living organisms to survive. However, the input of man-made greenhouse emissions has increased seriously in recent years. This has caused the greenhouse effect to become extreme, leading to Global Warming.
Greenhouse Gases and Global Warming
We may describe Global Warming as the gradual and continuous rise in global temperatures . Global Warming has been found to occur mainly as a result of the increasing levels of greenhouse gas concentrations in the atmosphere.
In the past three decades, there has been a 45 percent increase in the effect of greenhouse gases on global temperatures. This corresponds to the increase in the scale and rate of industrial developments. It also proves the role of greenhouse gases and their emission, in causing global warming
Global Warming would typically occur when pollutants and other greenhouse gases like carbon dioxide (CO2) accumulate in the lower atmosphere. These gases, mainly result from man-made sources and processes. On a long-term basis, global warming may lead to climate change.
Greenhouse Gases and Climate Change
The greenhouse effect is the main cause of climate change . This is because, the temperature increase caused by greenhouse gas emissions, over time, result in climatic changes.
By trapping heat close to the Earth’s surface, greenhouse gases increase the temperature of the Earth over long periods of time. This causes higher rates of rainfall, lower levels of glaciation, and higher background temperature conditions. Ultimately, it alters the climate.
Greenhouse Gas Emission Protocol
The Greenhouse Gas Protocol (GHGP) was developed by the World Resources Institute (WRI)and the World Business Council for Sustainable Development (WBCSD) in 1998. It is basically a set of standards for reporting, evaluating and accounting for greenhouse emissions.
Its purpose is to guide industries, corporate bodies and businesses at the local and international levels, with respect to how they can measure, and minimize their greenhouse gas emissions.
Like other climate change agreements and protocols it is ultimately aimed at reducing the rate of global warming and increasing the sustainability of the environment.
One of such similar regulatory entities is the Paris Agreement, which is committed to reducing greenhouse emissions in various countries and maintain global temperature increase below 1.5°C. This is geared ultimately toward addressing climate change and preserving the environment and the ecosystem.
The GHG Protocol was developed to aid industries, companies and countries as a whole, to report, manage and mitigate greenhouse emissions.
Greenhouse Gas Emission Statistics: Greenhouse Emissions by Country (2020)
|Country Data||Greenhouse Emissions (million metric tons of CO2 equivalent)|
|Country||Population||Land Area (Km2)||CO2||CH4||N2O||Fluorinated Gases||Total GHG Emissions|
|Antigua and Barbuda||97,929||440||0.54||0.21||0.02||—||0.77|
|Bosnia and Herzegovina||3,280,819||51,000||23.5||3.4||1.1||3.2||31.2|
|Central African Republic||4,829,767||622,980||0.5||24.0||32.2||-0.2||56.7|
|Czechia (Czech Republic)||10,708,981||77,240||106||12.5||5.2||-5.1||123.7|
|Democratic Republic of the Congo||89,561,403||2,267,050||3.1||38.7||15.9||-2.9||60.6|
|Eswatini (fmr. “Swaziland”)||1,160,164||17,200||1.1||1.55||0.5||0.7||3.85|
|Myanmar (formerly Burma)||54,409,800||653,290||48.4||66.0||21.6||5.3||141.3|
|Papua New Guinea||8,947,024||452,860||77.8||11.5||4.0||-1.4||94.7|
|Saint Kitts and Nevis||53,199||260||0.23||0.09||0.02||0.06||0.4|
|Saint Vincent and the Grenadines||110,940||390||0.1||0.08||0.01||-0.09||0.28|
|Sao Tome and Principe||219,159||960||0.21||0.04||0.03||0.08||0.36|
|Trinidad and Tobago||1,399,488||5,130||30.7||13.0||0.4||14.0||58.1|
|United Arab Emirates||9,890,402||83,600||203.1||53.1||7.2||-17.0||280.4|
|United States of America||331,002,651||9,147,420||4,535.3||623.1||0.3||38.0||5196.7|
The Table above shows greenhouse gas emissions in million tons for each of the four main groups of greenhouse gases. It is arranged to give these emission values for individual countries of the world, in the year 2020.
The values are derived, based on;
1). Actual 2020 emission values, where these are available from measurements
2). Approximate values based on percentage changes in emission annually. This is used were actual 2020 emission values are unavailable
3). Question mark (?) shows that the given emission value may need to be reviewed and validated
4). Short dashes (—) show that there is no reliable data available at all
Countries with Highest Greenhouse Emissions 2020
The ten countries which emitted the largest volumes of greenhouse gases in 2020 include Brazil, China, India, Iran, Japan, and the United States, among others.
These countries are mostly involved in industrialization, manufacturing and technology. They also generally have high populations.
Based on these observations, we can predict some of the factors which contribute to greenhouse emissions in any country. They include;
1). Population size
2). Level of Industrialization
3). Scale of Com
4). Level of Technological utilization
The plot below shows a comparison among the ten highest greenhouse gas-emitting countries in the world, in 2020;
Greenhouse Gas Emissions Relative Proportions (Worldwide)
The table below shows the approximate relative values of the different groups of greenhouse gases.
|Carbon dioxide (CO2)||75.9|
|Nitrous Oxide (N2O)||6.0|
|Fluorinated Gases (HFC, PFC, SF6)||2.0|
Greenhouse Gas Emissions by Sector (Worldwide, 2020)
The following table shows approximate relative proportions of greenhouse gas emissions from different economic sectors (values are subject to review);
|Sector||Greenhouse Gases (%)|
|Energy||Electricity and Heat||32.0|
This article has discussed the meaning of greenhouse gases. It has also identified the main groups and sources of these gases in the atmosphere.
The statistics show that global emissions are concentrated in some countries. It points to the role of population and industrialization in producing greenhouse emissions. The study also shows that greenhouse emissions are closely related to climate change and global warming.
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