Nowadays, there are many terms related to climate change and the actions that individuals and entities take to make a positive impact. However, some terms like carbon neutrality, carbon credits, carbon offsetting, and net-zero can be interpreted in different ways and cause confusion for some people. For that reason, it’s important to establish a shared vocabulary so that everyone can understand clearly and unambiguously what these terms mean.
Climate change traditionally refers to the constant, natural fluctuations in Earth’s climate, however recently has become the common term for the man-made, rapid changes happening since the Industrial Revolution. Other names include ‘global warming’, ‘the climate crisis’ and ‘the climate emergency’. Due to human activities - like burning fossil fuels - an excess of greenhouse gases accumulated in the air over time trapping heat in the atmosphere resulting in an overall warming effect. This increasing average temperature provokes severe changes in the climate as we know it.
The greenhouse effect is a natural phenomena in which the greenhouse gases in the atmosphere trap heat leading to an increased temperature. As mankind is increasing the amount of greenhouse gases in air, the greenhouse effect is intensified resulting in an unnatural, rapid rise in temperature changing the climate as we know it - anthropogenic (man-made) climate change.
Energy emitted by our sun comes in the form of ultraviolet, visible and near-infrared radiation of which a part radiates towards Earth. The part of this radiation, which is not reflected back to space, penetrates the atmosphere unimpeded and is absorbed by Earth’s surface. Earth itself, as all bodies, emits the same amount of radiation it absorbs - keeping it’s equilibrium temperature. As the Earth’s surface is colder than the suns', it emits a different type of radiation - a lower energy one with longer wavelengths - infrared radiation. Radiative active gases in the atmosphere - greenhouse gases - absorb this infrared radiation and emit it in all directions. Parts of it fall back on to Earth’s surface. Because of that, Earth receives twice as much radiation from the atmosphere as it does from the sun resulting in a higher temperature - this is referred to as the greenhouse effect.
This term refers to the total amount of carbon dioxide produced by a person, organization, or activity during a given period of time. The carbon footprint can also consider other greenhouse gases produced, such as methane, nitrous oxide, and chlorofluorocarbons.
It’s a useful measurement to monitor how much carbon dioxide and other greenhouse gas emissions are produced by a person, organization, or activity. It can be expressed by tons of CO₂ or CO₂-equivalent gases emitted per year.
Carbon offsetting1 is the action of reducing, avoiding or sequestering a unit of carbon dioxide or other greenhouse gases to compensate for emissions occurring somewhere else. Carbon offsetting is frequently done by purchasing carbon credits, but it can also be done by funding practices that actively remove carbon dioxide from the atmosphere. Carbon offset schemes allow companies and individuals to compensate for their carbon footprint, it’s a way to balance out their emissions or reduce the damage caused by a specific activity, such as traveling by plane.
According to the FAO2, carbon credits are a currency for trading carbon emissions in the carbon market. A carbon credit represents the right of an entity to release one ton of carbon dioxide or the equivalent amount of other greenhouse gases into the atmosphere. However, carbon credits have some limitations since the entity would be paying someone else to prevent a negative impact instead of actually removing carbon dioxide from the atmosphere. For example, if an entity emits two thousand tonnes of CO₂, it can purchase carbon credits to ensure that another entity reduces two thousand tonnes of CO₂ from its own emissions.
As defined by the UNEP1, carbon sequestration is the action of removing carbon from the atmosphere and depositing it in other carbon sinks, such as forests, the ocean or underground. These reservoirs store carbon dioxide for a long time and prevent it from entering the Earth’s atmosphere. For instance, forest regrowth is a form of carbon sequestration. Trees will remove carbon dioxide from the atmosphere through photosynthesis and use it to build wood, leaves, and roots. Therefore, they store carbon for a long time.
Carbon removal, carbon dioxide removal or CDR, refers to a group of anthropogenic activities that actively remove and sequester carbon dioxide from the atmosphere, according to the UNEP1. Carbon removal uses natural-based, technology-based, and combined natural/technology-based practices to create negative emissions. Even though carbon removal is essential to remove greenhouse gases already in the atmosphere, it isn’t a substitute for reducing carbon dioxide emissions and deforestation. Carbon removal practices and technologies include afforestation, carbon farming, direct air capture and storage, enhanced weathering, and others.
Negative emissions or greenhouse gas removal (GGR) is the withdrawal of a greenhouse gas from the atmosphere3. Carbon dioxide removal (CDR) or short carbon removal is a subgroup of GGR and refers to activities removing CO₂ and durably storing it in geological, terrestrial or ocean reservoirs, or in products. For some greenhouse gas-emitting activities like aviation, it’s currently impossible to get their emissions down to zero. Therefore, the best alternative for some entities is to combine reduction efforts with negative emissions to balance out their emissions.
Net zero emissions
According to the IPCC3, net-zero emissions are achieved when greenhouse gas emissions released into the atmosphere are balanced by negative emissions. If no emissions were produced in the first place, the term ‘zero emissions’ can be used. Entities can only achieve net zero via anthropogenic removals - the withdrawal of greenhouse gases from the atmosphere.
However, to get to net zero, it’s also important to dramatically reduce greenhouse gas emissions by replacing greenhouse gas-emitting technologies with clean ones. Only the unavoidable emissions should then be balanced out with removals to reach net zero.
Carbon neutrality, also refered to as net zero CO₂ emissions, is the same like net zero emissions but with swaping greenhouse gases for carbon dioxide. It is achieved if the amount of CO₂ emissions produced is equal the amount of CO₂ emissions removed from the atmosphere3.
Some companies have misinterpreted carbon neutrality, as they claim to be carbon neutral because of buying carbon credits. But purchasing low-quality carbon offsets doesn’t remove any emissions from the air in is thus not helping with carbon neutrality.
Climate positive means that an entity or activity removes more greenhouse gases from the atmosphere than it emits. In other words, it produces a positive impact that counteracts climate change. The term is very similar to carbon negative, which refers to the removal of more carbon dioxide than emitted.
To become climate positive, an entity shouldn’t rely on carbon offsets to delay reductions of its emissions. Carbon offsets should only be used in addition to other reduction efforts to reach the climate positive goal. For example, if a company produces two thousand tons of CO₂e per year but removes three thousand tons of CO₂e per year, it’s climate positive.