Climate Change Glossary

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. 

This article explores some of the activities that contribute to tourism’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.