Climate Change Glossary: Definitions of Key Terms
Confused by all of the climate terms out there and not sure what lingo to use? Our climate change glossary is designed to help you sort through all the jargon and demystify some of those technical sounding terms. Search below for definitions of the top terms you need to know when talking about climate change, carbon emissions, and climate action.
Climate Change: Refers to a long-term change in the average weather conditions of a place. Beyond changing temperatures, climate change can also alter precipitation patterns and increase the frequency and intensity of droughts, floods, hurricanes, and other extreme weather events. While some climate change occurs naturally, the current change in the global climate is happening at an unprecedented rate due to rising levels of greenhouse gases.
Global Warming: Though this term is often used interchangeably with “climate change,” global warming refers only to the rise in the Earth’s surface temperature. In other words, global warming is one aspect of climate change.
Emissions and Measurement
Greenhouse Gases (GHGs): Gases such as carbon dioxide, methane, nitrous oxide, and fluorinated gases which act like “greenhouses” by trapping heat in the atmosphere. As such, they play an important role in keeping the planet a livable temperature. While greenhouse gases are produced naturally, the amount of these gases that blanket the planet has skyrocketed since the Industrial Revolution.
Carbon Footprint: When you add up all of the greenhouse gas emissions (GHGs) that you produce – that’s your carbon footprint. A carbon footprint is usually expressed in metric tons (MT) of carbon dioxide equivalent (CO2e). Tools such as carbon footprint calculators or methodologies such as the GHG Protocol can be used to calculate a company or individual’s carbon footprint.
Carbon Dioxide Equivalent (CO2e): Along with carbon dioxide, there are other greenhouse gases, such as methane, and nitrous oxide, that also contribute to global warming. When measuring a carbon footprint, it is important to account for all of these GHGs; however, the challenge is that they each have a different effect on the climate. Carbon dioxide equivalent, abbreviated as CO2e, is a common unit for measuring greenhouse gases so they can be reported in a single combined footprint. It represents the amount of carbon dioxide that would have the equivalent global warming impact as another greenhouse gas, when measured over a 100 year timescale. For example, one metric ton of methane would be equal to 25 metric tons of CO2e, because it has a global warming potential 25 times that of CO2.
Metric Ton (MT): Also known as a tonne, a metric ton is a unit of mass equal to 1,000 kilograms or 2204.62 pounds. It is the standard unit used for reporting CO2e emissions. This should not be confused with a US ton, which is a unit of mass equal to 2,000 pounds or approximately 907.19 kilograms.
Scope 1, 2, and 3 Emissions: A carbon footprint can be broken down into three different scopes, or classes of emissions sources, as identified by the GHG Protocol which provides the world’s most widely used greenhouse gas accounting standards.
- Scope 1 Emissions: Direct emissions from fuel combustion in owned equipment such as furnaces, boilers, vehicles, etc. Scope 1 also includes any fugitive emissions such as the Hydrofluorocarbons (HFCs) released by refrigeration and air conditioning systems.
- Scope 2 Emissions: Indirect emissions from the electricity, steam, heat, or cooling an individual or company purchases from a utility provider.
- Scope 3 Emissions: All other indirect emissions that are associated with an individual or company’s activities. Scope 3 emissions are produced by assets that are not owned by the individual or company. This includes emissions generated across the supply chain from the procurement of goods/services, employee travel and commuting, and waste disposal.
Carbon Sink: a natural or artificial reservoir which absorbs and stores more carbon from the atmosphere than it releases. Examples of natural carbon sinks include trees, mangroves and other plants, as well as soils and oceans; whereas artificial carbon sinks include man-made sinks such as carbon capture and storage technologies.
Climate Targets and Action
Science-Based Targets: Emissions reduction targets that are in line with what the latest climate science deems necessary to meet the Paris Agreement goal of limiting global warming to 1.5°C above pre-industrial levels.
Climate Mitigation: Taking action to address the root causes of climate change by preventing or reducing the release of greenhouse gas emissions into the atmosphere.
Climate Adaptation: Taking action to adjust to the changing climate in order to minimize harm from the inevitable impacts of climate change such as rising sea levels, drought, tropical storms, etc. Examples of climate adaptation strategies include restoring coastal buffer zones, planting climate resilient crops, reusing greywater, and fortifying buildings and infrastructure.
Carbon Neutral: To be ‘carbon neutral,’ an individual or company must achieve a balance between the amount of emissions they produce across all scopes (1, 2, and 3) and the amount they remove or offset. An individual or company can achieve carbon neutrality without having reduced their own emissions.
Net Zero: To go ‘net zero,’ an individual or company must reduce their greenhouse gas emissions as much as possible across all scopes (1, 2, and 3), and ensure that any remaining emissions are balanced out through offsetting or removals.
Absolute Zero / Zero Emissions: This state is reached only when an individual or company’s activities result in no GHG emissions across all scopes (1, 2, and 3). To achieve absolute zero / zero emissions, no offsets or other carbon removal schemes are used to balance out emissions.
Climate Positive: An individual or company can be ‘climate positive’ by removing/offsetting more emissions than they produce. ‘Carbon negative’ is another term that means the same thing as ‘climate positive.’
Carbon Offsetting: A process by which individuals and companies balance out, or compensate for, their own carbon footprint by financing an emissions reduction elsewhere. When an individual or company buys carbon offsets, their money funds climate projects that are verified to either remove existing carbon from the atmosphere or avoid future emissions.
There are different types of carbon offset projects located around the world, and their activities may include building wind farms, protecting forests, restoring mangroves, or installing waste-to-energy systems. These projects often create benefits that go beyond emissions reductions, benefiting local communities and safeguarding natural biodiversity.
Carbon Credit: When you offset your carbon footprint, you are essentially purchasing a certain number of carbon credits. Each carbon credit represents 1 metric ton of CO2e removed or averted from the atmosphere. So to offset 10 metric tons of carbon, you would need to purchase 10 carbon credits.
Each carbon offset project issues a certain number of carbon credits that corresponds to the total amount of carbon emissions that will be reduced during its lifespan. When you purchase carbon credits, the funds are distributed to the project, making the continuation of its activities economically feasible.
Carbon credits are a tradable commodity. When an individual or a business purchases a carbon credit to offset their emissions, it must be permanently retired from the market to ensure that someone else can’t also buy it. When you offset carbon with Sustainable Travel International, we take care of purchasing the carbon credits for you and making sure they are consequently retired.
While many companies purchase carbon credits voluntarily (this is known as the voluntary carbon market), some companies are legally required to purchase carbon credits in order to meet international and national regulatory targets. (this is known as the compliance carbon market).
More information about the difference between the voluntary and compliance carbon markets can be found on our carbon offsets FAQ page here.
Carbon Offset Project Developer: the individual or organization who oversees the coordination and implementation of a carbon offset project.
Carbon Offset Standards: A standard is a set of criteria against which carbon offset projects’ environmental and social co-benefits can be certified or verified. In the voluntary markets, a number of competing standard organizations have emerged with the intent of increasing credibility in the marketplace.
You can learn more about the different carbon offset standards on our quality assurance page.
Carbon Offset Registries: databases which issue carbon credits for verified offset projects and track the ownership, sale, and retirement of these credits. Each carbon credit is given a unique serial number to track its ownership throughout its lifetime. A carbon credit can change ownership multiple times; however, if the buyer wants to claim the credit as a carbon offset, then it must be permanently retired on the registry so it can’t be resold. As such, registries are important to minimize the risk of double-counting.