Afforestation is the process of planting new trees on land that didn’t used to contain a forest. This can be done for numerous reasons, such as to combat climate change, to provide timber, or to restore ecosystem services. The reason trees are particularly effective at combatting climate change is that they absorb CO2 as they grow.

Anthropogenic removals refer to the process of removing greenhouse gases from the atmosphere by way of human intervention. This can be done through methods such as enhancing carbon sinks or carbon capture and storage (capturing CO2 emissions and storing them underground) combined with bioenergy. The idea behind anthropogenic removals is that they can help mitigate the effects of climate change by reducing the amount of GHGs in the Earth’s atmosphere. Although these methods are still being studied and developed, they will likely play a central role in future climate action efforts.

A baseline year, or “base year”, is a reference point used to measure and track an organization's changes in emissions over time. As a base year, an organization can use the year for which it has the most data or which best reflects its operations. For example, the IPCC’s baseline year, 2010, is used to project that total global emissions must be reduced by 45% by 2030 to reach net zero by 2050.

Bioenergy refers to energy that is produced by living organisms, such as plant material, agricultural waste, and forestry residues (tops and branches left over from forest harvesting or clearing). It is considered a renewable resource as, unlike fossil fuels (which are finite), the materials used to produce bioenergy can be replenished or regrown over time. There are several different types of bioenergy, including biogas and biofuels such as bioethanol and biodiesel.

Biofuels such as ethanol and biodiesel are made from biomass (plant material such as sugar cane or corn) and can be used as substitutes for gasoline and diesel. One of the main factors inhibiting the use of biofuel today is its financial costs, which are around 70-130% higher than petrol and diesel.

Biomass is organic material that comes from plants and animals, such as animal manure, corn, food waste, vegetable oil, algae, wood, and even human sewage.

Biomass can be used as fuel to produce heat or electricity. In fact, biomass was the largest source of total annual U.S. energy consumption until the mid-1800s. It continues to be an important fuel source, particularly in developing countries, where it is often used for cooking and heating.

Blue carbon is carbon that’s naturally captured by living organisms in coastal ecosystems (e.g., mangroves, salt marshes, seagrasses) and the ocean. This carbon is stored in biomass (see above) and sediments.

Carbon capture and storage (CCS) is the process of capturing CO2 and storing it before it’s released into the atmosphere. CSS technology can capture 90-100% of the CO2 released by burning fossil fuels in electricity generation and industrial processes such as cement production. Once the CO2 has been captured, it is compressed into a liquid state. It is then transported via pipeline, ship, or road tanker and pumped underground, where it’s stored.

Although CCS is costly and still under development, the IPCC believes that it will play a critical role in helping to reduce emissions and limit global warming.

A carbon credit is a tradable certificate or permit that represents the right to emit a certain amount of CO2 or CO2 equivalent (CO2e). A carbon credit represents the prevention of one metric ton of CO2e released into or removed from the atmosphere.

The carbon cycle is basically nature’s way of reusing carbon. Naturally, carbon atoms are continuously circulated throughout the Earth's atmosphere, oceans, and land. The carbon cycle helps regulate the amount of CO2 in the atmosphere, so it’s a crucial component of the Earth's climate.

Where the likes of oceans and forests (also known as carbon sinks) absorb and store CO2, things like volcanoes, burning fossil fuels, and decomposition (also known as carbon sources) release CO2 back into the atmosphere. However, some processes, like the burning of fossil fuels and deforestation, release more CO2 into the atmosphere than they absorb. This disturbs the natural balance, leading to excess CO2 in the atmosphere, which in turn is changing our climate by way of increasing global temperatures, causing ocean acidification, and disrupting the planet’s ecosystems.

Carbon dioxide removal (CDR) is the process of removing CO2 from the atmosphere. Because CDR is the opposite of emissions, practices or technologies that remove CO2 can be described as achieving ‘negative emissions’.

The two primary kinds of CDR are: 1. Developing existing natural carbon removal processes (e.g., by reforestation and afforestation), or 2. by using CCS or DAC.

Offsetting is a way to compensate for the GHG emissions that an organization or individual could not reduce by investing in projects or activities that reduce or remove the equivalent amount of emissions through things like renewable energy, carbon capture and storage (CCS), or reforestation.

Offsetting should be undertaken only after every effort has been taken to reduce emissions. To avoid accusations of greenwashing, companies need to consider how, and how much, they rely on carbon offsets to achieve their net zero goals.

Where carbon offsetting has companies investing in external projects or activities to compensate for their emissions, carbon insetting turns inwards, financing projects within its own value chain. An example of this could be a hotel planting trees in its outdoor areas or a restaurant growing its own fresh produce.

A carbon sink is anything that absorbs more carbon from the atmosphere than it releases. Examples include plants, the ocean, and soil. These carbon suckers continually take carbon out of the atmosphere through the process of photosynthesis.

In contrast to a carbon sink, a carbon source is anything that releases more carbon into the atmosphere than it absorbs. Examples of this include the burning of fossil fuels or volcanic eruptions.

A carbon tax is a tax that companies or individuals must pay to the government for each ton of GHG emissions emitted. Carbon taxes come in two broad forms: an emissions tax, which is based on the amount of emissions an entity emits, and a tax on GHG-intensive goods or services, like gasoline.

Carbon taxes are intended to reveal the hidden or indirect social costs of carbon emissions, such as extreme weather events. Their goal is to make fossil fuels more expensive, incentivizing individuals and organizations to reduce their emissions by reducing their energy use or using cleaner energy sources.

Carbon trading is a system that lets companies or countries buy and sell allowances for the amount of GHGs they emit. The concept behind carbon trading is to put a price on carbon, which creates a financial incentive for companies and countries to reduce their environmental footprint.

There are two main types of carbon trading systems: cap-and-trade and carbon tax.

Cap-and-trade systems limit (or “cap”) the amount of GHGs that companies or countries can emit. These limits are set by the government, which issues a certain number of allowances or "permits to pollute" to each sector every year. Companies that emit fewer GHGs than they are allocated can then sell their leftover allowances to companies emitting more than permitted.

Carbon taxation is a policy where a fixed price must be paid for each ton of CO2 emitted. This is done by taxing the carbon content of fossil fuels at the point of production or importation. The aim is to make fossil fuels more expensive and encourage the use of cleaner energy sources.

Both cap-and-trade and carbon taxation aim to reduce the amount of GHGs in the atmosphere by putting a price on carbon and thus creating an economic incentive for companies to reduce their emissions.

Climate justice refers to the idea that the burdens of climate change, its mitigation, and its associated responsibilities should be shared fairly and equitably. The concept also takes into account the idea that those most responsible for causing climate change, such as highly industrialized countries and large corporations, have a moral obligation to support those most affected by, and most ill-equipped to adapt to, its impacts.

Carbon neutral generally refers to the balance between the amount of carbon an organization, product, or individual emits into the atmosphere and the amount removed or offset.

Becoming carbon neutral is a process that takes time and effort, requiring continual monitoring, reporting, and reduction of emissions over time.

Being climate positive is the same as being carbon negative, which means that an organization reaches net zero carbon emissions and also removes additional CO2 from the atmosphere, thus positively affecting the climate.

Decarbonization is the process of reducing something’s carbon content, generally in order to reduce GHG emissions and mitigate the effects of climate change.

In terms of energy production, decarbonization frequently refers to the transition away from fossil fuels, like coal, oil, and natural gas (which release a lot of CO2 when burned), to cleaner energy sources that have a lower carbon footprint (like renewable energy sources and nuclear energy).

Decarbonization can also refer to the process of reducing carbon emissions in industries, such as transportation, buildings, and agriculture. This could involve things like switching to electric vehicles, improving energy efficiency, and adopting sustainable farming practices.

Want to know more? You can learn about how data science can aid in the fight against climate change and support decarbonization efforts here.

Deforestation refers to the removal of forests, either through natural processes or human activity. Deforestation contributes significantly to GHG emissions, as forests play a crucial role in regulating the Earth's temperature and mitigating climate change by absorbing CO2 from the atmosphere.

Deforestation can result from activities such as the conversion of forestland to agriculture, the extraction of timber and other forest products, and the development of infrastructure. It can also be caused by natural events such as fires and storms.

Deforestation can have many negative impacts, including the loss of habitat for wildlife, the degradation of ecosystems, and the emission of GHGs from forest clearing and burning. Additionally, they further contribute to climate change, as forests play a vital role in regulating the Earth's temperature and absorbing carbon dioxide from the atmosphere.

To address deforestation and its impacts, it’s important to implement policies and practices that promote sustainable land use and support the conservation and restoration of forests.

Direct air capture (DAC) is a technology that captures CO2 directly from the air, rather than capturing it once it’s released by industrial processes like power generation or cement production. The technology uses filters (or other mediums) to absorb CO2, which is then compressed into a liquid form for storage.

DAC is useful for lowering the emissions of certain sectors that are difficult to decarbonize, such as aviation and long-haul transportation. Although it’s considered to be a relatively expensive way to reduce emissions, DAC technology is still being tested and, once further developed and widely deployed, could become a more financially feasible option.

The energy transition is the global, gradual shift from using fossil-based energy sources to operating on a low- or zero-carbon system by 2050.