The quest to reduce emissions and reach net zero can be confusing.
To make it easier, Farmers Weekly teamed up with the AHDB and Trinity AgTech to provide some plain English definitions.
See also: 6 soil carbon schemes for farmers to consider
Additionality
Reductions by a genuine carbon offset (see definition below) must be “additional” to what would have been achieved had the project not been carried out. (FW)
Afforestation
When new trees are planted or seeds are sown in an area where there were no trees before, creating an entirely new forest. (AHDB)
Agroforestry
Land use management system in which trees or shrubs are grown among crops or pastureland. (TA)
Ammonia
Ammonia is not classified as a greenhouse gas. But it can have a damaging impact on biodiversity and disrupt sensitive habitats and ecosystem resilience. It also harmful to human and animal health. (AHDB)
Baselining
Every project needs to determine what its emissions would have been if the project was not implemented (its baseline emissions). The number of credits a project receives is calculated by subtracting the project emissions from the baseline emissions. (TA)
Biodiversity
Variety of plant and animal life found on Earth or within a particular habitat. (TA)
Carbon
A chemical element. Solid at room temperature, carbon atoms are extremely abundant and stored in soils, plants and fossil fuels. It is often incorrectly and confusingly used as shorthand for carbon dioxide. (AHDB)
Carbon credit
Permit that allows the owner to emit a certain amount of carbon dioxide or other greenhouse gas. Usually one credit allows emissions of 1t of carbon dioxide equivalent. (AHDB)
Carbon dioxide
Gaseous molecule made up of one carbon atom and two oxygen atoms. It is mainly emitted by respiration and combustion, and as the benchmark global warming agent is assigned a potential of 1. It persists in the atmosphere for 300-1,000 years according to Nasa. (AHDB)
Carbon dioxide equivalent (CO2e)
Yardstick measurement with a global warming potential of 1.
Other gases have their potential expressed as the equivalent amount of carbon dioxide, usually expressed in million tonnes of carbon dioxide equivalents.
Methane, for example, has a CO2e 28 times that of carbon dioxide. This means every 1m tonnes of methane released will be equivalent to emissions of 28m tonnes of carbon dioxide. (AHDB)
Carbon v carbon dioxide
Plants and soil store carbon, but carbon dioxide in the atmosphere contributes to climate change.
One tonne of carbon is equal to 3.67t of carbon dioxide so 10t of carbon stored is equivalent to 36.7t of carbon dioxide emissions. (AHDB)
Carbon finance
Money made available by a private firm or government to another business in exchange for storing or sequestering carbon. (AHDB)
Carbon flux
When carbon moves between two systems, such as plant material and the atmosphere. (AHDB)
Carbon footprint
The impact of a production process on climate change is calculated and expressed as its carbon footprint. (AHDB)
Carbon insets/ insetting
Offsetting emissions through a carbon project within the same supply chain. In contrast, carbon offsetting is when an organisation buys carbon credits to offset its emissions externally. (TA)
Carbon intensity
Every product or action has a different carbon “cost”. The amount of carbon emitted per action is its carbon intensity – for example, the amount of carbon dioxide created for every kilogram of fresh produce. (TA)
Carbon neutral
When the amount of carbon being removed from the atmosphere by a process or action is exactly equal to the carbon emitted. (TA)
Carbon offsets/offsetting
Reduction or removal of carbon dioxide emissions, or other greenhouse gases, to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide equivalent (CO2e).
When one company removes a unit of carbon dioxide from the atmosphere, it can generate a carbon offset, which can be bought by another company to reduce its footprint. (TA)
Carbon reduction
Cutting the amount of emissions that would happen under business-as-usual circumstances. (TA)
Carbon removal
Drawing carbon dioxide out of the atmosphere and storing it in natural reserves such as soil or plants. Also known as “sequestration”. (TA)
Carbon retention
Act of retaining carbon in trees or soil once it has been removed or “sequestered”. (TA)
Carbon reversal
Release of carbon stored in trees or soil back into the atmosphere, whether intentionally or unintentionally. (TA)
Carbon sink
If the carbon sequestered exceeds the amount emitted, the store of carbon is increasing and is known as a carbon sink. (AHDB)
Carbon stocks
Amount of carbon held in an ecosystem. For example, soils where quantities vary enormously, ranging from sandy arable soils with less than 40t/ha of carbon to peat soils with up to 300t/ha. (AHDB)
Carbon trading
Process of buying and selling carbon permits and carbon credits that allows the permit holder to emit carbon dioxide.
Companies can pay another firm to sequester carbon instead of reducing their own emissions. (AHDB)
Climate change
Process by which the climate alters over periods of many years. (AHDB)
Co-benefits
Additional environmental, social, health, or economic benefits that accompany a carbon project.
These additional benefits often support the United Nation’s sustainable development goals and can help bolster the value of a carbon credit. (TA)
Deforestation
Deliberate clearance of forested land to make way for agriculture or development. (AHDB)
Denitrification
Microbial process of changing nitrates into gaseous forms of nitrogen, such as nitrous oxide and nitrogen. It is one of three ways nitrogen is lost from the soil.
The other ways are volatilisation and leaching. (AHDB)
Feedback loop
Spiral that accelerates (positive) or decelerates (negative) a trend. Clouds, for example, hold heat radiated from land.
As air warms, water evaporates – creating more vapour in the atmosphere. The extra vapour holds in more heat and the process accelerates. (AHDB)
Global warming potential (GWP)
Measurement of how much impact a gas has on atmospheric warming compared to carbon dioxide.
Each greenhouse gas has a different atmospheric warming impact, and some remain in the atmosphere longer than others.
The most common metric to measure greenhouse gas emissions is GWP100 – global warming potential measured over 100 years.
GWP*
Means of measuring carbon in the atmosphere, taking into consideration the effect of short-lived gases (such as methane). (TA)
Greenhouse gas (GHG)
Gases that trap heat when released into the atmosphere, causing global warming and climate change. (TA)
Greenwash
A form of advertising or marketing to make people believe an organisation is more environmentally friendly than it is. (TA)
IPCC Guidelines
The Intergovernmental Panel on Climate Change (IPCC) is the UN’s body for assessing the science related to climate change.
It provides a technically sound, methodological basis of national greenhouse gas inventories, prepared by the Task Force on National Greenhouse Gas Inventories.
The latest refinement took place in May 2019 during the IPCC’s 49th Session in Kyoto, Japan. (TA)
International Standards Organisation
ISO is a worldwide network of experts who develop internationally agreed standards for products, processes, services and materials. (TA)
ISO 14064 accreditation
Principles and requirements providing guidance at project level for the quantification, monitoring and reporting of activities intended to cause greenhouse gas emissions reductions or removal enhancements. (TA)
ISO 14065 accreditation
Principles and requirements for bodies that carry out validation or verification of greenhouse gas claims. (TA)
Methane
One of the two main greenhouse gases emitted by agriculture. It has 28 times the impact of carbon dioxide but persists for much less time in the atmosphere.
Methane is largely a product of livestock production, mostly from enteric fermentation in ruminants but also from slurry, manure and waterlogged land. See “nitrous oxide”. (AHDB)
Mitigation
Process of finding ways to reduce greenhouse gas emissions caused by human activity. (AHDB)
Natural capital
Stock of natural resources or assets on the Earth – among them geology, soil, air, water and living organisms, including trees. (AHDB)
Net carbon balance
Difference between the total greenhouse gas emissions and the total carbon dioxide sequestration caused by an individual, event, organisation, service, place or product.
Expressed as carbon dioxide equivalent. (TA)
Net zero
Target of completely negating the amount of greenhouse gases produced by human activity.
Net zero is achieved by reducing emissions and implementing methods of absorbing carbon dioxide from the atmosphere. (AHDB)
Nitrate
Compound made up of nitrogen and three oxygen molecules. Nitrates are a major nutrient for plant growth, but too many nitrates in water can lead to ecological imbalances. (AHDB)
Nitrous oxide
Second of the two main greenhouse gases emitted by agriculture. More potent than methane, nitrous oxide has 298 times the global warming potential of carbon dioxide.
It persists in the atmosphere for more than 120 years – 10 times longer than methane.
Emissions occur mainly from cropped land because nitrous oxide is mostly created by fertiliser production and its breakdown in the soil, together with the decay of other organic matter. (AHDB)
Reduction/removal/retention credits
Carbon credits associated to carbon reduction/removal/retention. (TA)
Reforestation
Process of planting trees in an existing forest where the number has been decreasing. (AHDB)
Renewable energy
Often shortened to renewables, the term refers to energy generated from naturally replenished resources such as sunlight, wind, water and biomass. (AHDB)
Scope 3 emissions
Emissions not produced by the farm itself, and not the result of activities from assets it owns or controls, rather by those it’s indirectly responsible for within the supply chain.
An example of this is employee travel or when we buy, use and dispose of products from suppliers. (TA)
Soil carbon
Carbon stored in soil’s organic matter. It comes from decomposing plant material and is vital for soil health. About 58% of soil organic matter is carbon, also known as soil carbon. (AHDB)
Sequestration
Process by which carbon dioxide is removed from the atmosphere and stored in solid or liquid form. (AHDB)
Volatilisation
The loss of applied nitrogen through the conversion of ammonium into ammonia gas, which is released to the atmosphere.
Losses occur from surface application of fertiliser containing urea. In addition to leaching and denitrification, volatilisation is one of the three main nitrogen loss mechanisms. (AHDB)
Water leaching
Movement of contaminants, including pesticides and fertilisers, carried by water into the soil, where it can take a long time to break down. (TA)
Water vapour
Arguably the most important greenhouse gas of all, water vapour is responsible for about half of Earth’s greenhouse effect.
As global temperatures rise, evaporation increases from oceans and lakes to create water vapour, which then absorbs heat radiated from the earth and prevents it from escaping out to space.
This creates a positive feedback loop, further warming the atmosphere in even more water vapour in the air. (AHDB)
