Emissions

Emission means (when in the context of climate and sustainability) the release of substances directly into the air or atmosphere over a specified area and period of time that pollute or harm the environment including the health of humans and animals. One class of these gases that harm the environment are greenhouse gases (GHG). When greenhouse gasses get emitted into the atmosphere they enhance the greenhouse effect of planet earth and cause the surface temperature to rise. Greenhouse gases are causing the climate change of planet earth.

What is the difference between emission and imission?

Emission means the mass of substances released into the atmosphere over a period of time. Imission is the concentration of pollutants or substances that harm the environment in the atmosphere that we can measure.

Greenhouse gases

What is the definition of greenhouse gases?

Greenhouse gas (sometimes indicated as GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range. As a result of the greenhouse gases in the atmosphere, planet Earth has a so-called greenhouse effect. The greenhouse effect is the way that heat is trapped close to the service of the Earth due to greenhouse gases. Greenhouse gases are often described as a blanket around the Earth trapping the heat of the earth. If greenhouse gasses would not exist, planet Earth would have an average of -18 degrees Celsius instead of the 15 degrees Celsius that the average temperature is of planet Earth (at the moment). Not only planet Earth has greenhouse gases, but also Venus, Mars and Titan have greenhouse gases. Having greenhouse gases in the atmosphere is necessary for life on earth and e greenhouse gases have cycles as well. For example, Carbon dioxide is a GHG that plants use to make glucose. After the glucose is formed there are four reactions that can happen to get the carbon dioxide back into the atmosphere. 1. The plant breaks down the glucose for energy to grow and releases the energy to the atmosphere, 2. Humans or animals eat the plant and break down the glucose for energy and release the carbon back into the atmosphere, 3. Plant die and decay and the glucose get broken down by bacteria releasing carbon dioxide in the atmosphere and number 4. Plants get burned and the glucose reacts with the oxygen and gets released into the air as carbon dioxide. New plants can grow using the carbon dioxide that is released back into the atmosphere. The release of carbon dioxide becomes only a problem under one of these conditions:

• Deforestation: There are much fewer plants to absorb the carbon dioxide resulting in an excess of carbon dioxide in the atmosphere
• Burning fossil fuels: Fossil fuels are stored glucose from plants and under particular conditions turned into fossil fuel. Glucose

is not part of the carbon cycle. When the fossil fuel gets burned, extra carbon dioxide gets released into the air resulting in an excess of carbon dioxide in the atmosphere.

Both these scenarios (and sometimes even combined) result in an enhanced greenhouse effect making the temperature of the earth rise.

Industrial revolution

Since the beginning of the industrial revolution, humans have increased the atmospheric concentration of carbon dioxide massively. With this amount of greenhouse gasses in the atmosphere, the average temperature of planet earth could increase by 2 degrees Celsius with massive consequences. The vast majority of the emission of greenhouse gasses is due to burning fossil fuels, cement production, fertilizers production and deforestation.

The Earth's atmosphere

The earth's atmosphere consists of 3 main gases: 78% nitrogen (N2) 21% Oxygen (O2) 0,9% Argon (Ar) These gases are no greenhouse gases. What makes a gas a greenhouse gas is the ability to absorb and emit radiant energy within the thermal infrared range. Molecules containing 2 of the same atoms like nitrogen and oxygen have no net change in distributing their electoral changes when the vibrate and monoatomic molecules like Argon do not vibrate at all and both are therefore almost totally unaffected by infrared radiation. The last 0,1% of the Earth's atmosphere includes greenhouse gases

What are the 9 greenhouse gases (GHG)?

• Water vapour (H2O)
• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Ozone (O3)
• Industrial gases:
  • Hydrofluorocarbons (HFCs)
  • Perfluorocarbons (PFCs)
  • Sulfur hexafluoride (SF6)
  • Nitrogen trifluoride (NF3)

Air pollutants like ammonia (NH3) are the other type of gaseous emissions from agriculture. They are not greenhouse gases, but they do negatively impact human and animal health while also damaging ecosystems.

Water vapour (H2O)

Water vapour accounts for the largest percentage of the greenhouse effect. When the sky is clear the greenhouse effect of water vapour is lower than when the sky is very cloudy. Human activities do not directly influence the amount of water vapour in the atmosphere except for the local scale. For example the use of water irrigation. Even though water vapour is a greenhouse gas it is not the cause of global warming. Water vapour is an indirect effect of global warming also called water vapour feedback. Because of global warming, there is more water vapour in the atmosphere, as a result, there is positive feedback resulting in more heat getting trapped. However, the cloud does also reflect solar radiation. Even though water vapour accounts for the largest percentage of the greenhouse effect, water vapour has been stable and has an average residence of 9 days compared to centuries like other GHG. Therefore water vapour is not the biggest concern in the case of global warming and climate change.

Carbon dioxide (CO2)

Carbon dioxide has a natural occurrence in nature and a cycle through land, ocean and atmosphere. In 2020 carbon dioxide accounted for 79% of all US GHG emissions caused by human activities. The main emissions of carbon dioxide by human activity

• Transportation: transportation by using fossil fuels like diesel or gasoline to transport goods and people. Transportation was the largest source of carbon dioxide in 2020
• Electricity: Fossil fuels are used to generate electricity. To generate an amount of electricity using fossil fuels, burning coal will produce more carbon dioxide than natural gas or oil.
• Industry: Industrial processes emit carbon dioxide directly by burning fossil fuels or indirectly by using energy that is generated by fossil fuels.

Methane

Globally between 50% and 65% of all methane emissions comes from human activity and in 2020 methane accounted for 11% of all US GHG emission by human activities. The main sources of methane by human activity

• Agriculture: Domestic livestock like cattle, sheep, swine etc. Methane is naturally produced by animals and when animal manure is stored methane gets produced
• Energy & Industry: Natural gas and petroleum systems are the second largest source of methane. Methane is a primary component of natural gas as well as coal mining.
• Waste from homes and businesses: Methane is generated in landfills when waste decomposes and in the treatment of wastewater. Methane is also produced/generated from domestic and industrial wastewater treatment, composting and anaerobic digestion.

Nitrous Oxide

Nitrous oxide accounts for about 7% of all US greenhouse gas emission caused by human activities and globally around 40% of all nitrous oxide emission is due to human activities. The main sources of nitrous oxide by human activity

• Agriculture: Agriculture soil management activities like application of fertilizers, synthetic as well as organic and other cropping practices.
• Fuel combustion: Nitrous oxide is emitted when fossil fuels are burned. The amount of nitrous oxide that gets emitted depends on the type of fuel, combustion technology maintenance and operating skills.
• Industry: Nitrous oxide is a byproduct during the production of chemicals such as fertilizers or nylon
• Waste: Nitrous oxide is generated from the treatment of domestic wastewater during nitrification and denitrification of nitrogen present, usually in the form of urine, ammonia and proteins.

Fluorinated Gases

Fluorinated gases come entirely from human activities emitted via a variety of industrial processes such as aluminium and semiconductor manufacturing. Fluorinated gases are the most potent and longest-lasting type of greenhouse gas emitted by humans The main sources of fluorinated gases by human activity

• Used as a substitution for ozone-depleting substances: Fluorinated gases are used as a substitution for gases that damage the ozone layer. Mostly in the form of refrigerants (air-conditioning), aerosol propellants, fire retardants, foam-blowing agents and solvents.
• Industry: Perfluorocarbons are produced as a by-product of aluminium production and are used in the manufacturing of semiconductors, sulfur hexafluoride is used in magnesium processing and semiconductor manufacturing and as a tracer gas for leak detection. Nitrogen trifluoride is used in semiconductor manufacturing.
• Transmission and distribution of electricity: Sulfur hexafluoride is used as an insulating gas in electrical transmission equipment including circuit breaks. The GWP of sulfur fluoride is 22,800 GWP making it de most potent greenhouse gas that the intergovernmental penal on climate change has evaluated

What are the most significant sources of emissions per GHG that gets emitted?

The global warming potential

The global warming potential indicates how much energy the emission of 1 ton of a gas will absorb. The higher the GWP the bigger the thread of the GHG to global warming. By using the GWP the impact of different greenhouse gasses can be compared. GWP of the 4 largest sources of emission:

• Carbon Dioxide: 1 GWP regardless of the time period
• Methane: 27-30 GWP over 100 years
• Nitrous Oxide: 273 GWP over 100 years
• Chlorofluorocarbon, hydrofluorocarbon, hydrochlorofluorocarbon, perfluorocarbon and sulfur hexafluoride: High GWP's, somewhere in the thousands or even ten thousand

Three groups or scopes

Greenhouse Gas Emissions are categorised into three groups or 'Scopes' by the most widely-used international accounting tool, the Greenhouse Gas (GHG) Protocol. Scope 1 covers direct emissions from owned or controlled sources. Scope 2 covers indirect emissions from the generation of purchased electricity, steam, heating and cooling consumed by the reporting company. Scope 3 includes all other indirect emissions that occur in a company’s value chain.

Scope 1	Scope 2	Scope 3
Fuel combustion Company vehicles Fugitive emissions	Purchased electricity, heat and steam	Purchased goods and services Business travel Employee commuting Waste disposal Use of sold products Transportation and distribution (up- and downstream) Investments Leased assets and franchises

Emissions in Farming

• Mitigatin GHG Emissions in Beef Dairy systems

Documents & External links

• Greenhouse Gas Emissions
• Carbon Calculator - LCA
• The Carbon Almanac, by Seth Godin