Climate Change Glossary

Anthropogenic: Originating in human activity, as in anthropogenic emissions.

Carbon cycle: The global flow of carbon through the atmosphere, biosphere, geosphere, hydrosphere, and pedosphere.

Carbon dioxide (CO₂): A byproduct of burning fossil fuels, burning biomass, land-use changes or industrial processes (such as cement production). CO₂ is the principal anthropogenic GHG that affects the Earth’s radiative balance.

Carbon dioxide capture: A process to separate CO₂ from industrial and energy-related sources, and then compress and transport it for long-term storage. When CO₂ is captured and used to produce a new product, that process is known as carbon dioxide capture and utilization. If the CO₂ is stored in a product for a climate-relevant period, the process is known as carbon dioxide capture, utilization and storage (CCUS). The process of storing carbon in a carbon pool is known as carbon sequestration.

Carbon dioxide removal: The anthropogenic capture, compression, transportation and long-term storage of atmospheric CO₂ in geological, terrestrial, or ocean reservoirs, or in products. The term generally encompasses direct air capture and storage, as well as existing and potential enhancements of biological or geochemical sinks. It does not include natural CO₂ uptake not caused by human activities.

Carbon dioxide equivalent (CO₂e): A metric measure used to compare the emission intensity of different GHGs based on their global warming potential (GWP), which equates to the total energy that a gas absorbs over a specified period (usually 100 years), compared to CO₂. GWP represents the combined effect of the differing time spans GHGs remain in the atmosphere and their relative effectiveness in absorbing outgoing thermal infrared radiation (i.e., the radiation emitted by the surface of the Earth, the atmosphere and clouds).

Carbon footprint: A measure of GHG emissions in a specified period of time, such as the amount of GHG emissions associated with individual, corporate, government, or other activities.

Carbon intensity: The relative amount of carbon emitted per unit of a selected variable such as gross domestic product, transportation, or output energy use.

Carbon neutral: The state of making no net release of carbon dioxide to the atmosphere, especially through offsetting emissions.

Carbon offset: An emissions unit representing reduction or removal of GHG emissions, typically measured in tons of CO₂.

Carbon pool: A reservoir of carbon that has the capacity to accumulate or release carbon, including above-ground biomass, below-ground biomass, dead wood, litter (non-living biomass lying dead in various states of decomposition above mineral or organic soil) and soil carbon.

Carbon price: A financial value assigned to GHG emissions used to account for the climate impacts of those emissions, which are typically borne by individuals and governments. A carbon price may be a theoretical or notional cost, or it may be an internal tax/fee charged to a business activity based on emissions.

Carbon sinks: Natural environments that naturally absorb more CO₂ than they release, including oceans (namely algae, vegetation, and coral under the sea), forests, plants, and soil.

Climate: Average weather, measured over a period of time (the World Meteorological Organization uses 30 years), usually based on surface variables such as temperature, wind, and precipitation.

Climate change: The IPCC defines climate change as a change in the state of the climate that can be measured by changes in the mean and/or the variability of its properties and that persists for an extended period of time. The IPCC definition encompasses both climate change attributable to human activities altering atmospheric composition and climate variability attributable to natural causes. Other definitions (e.g., in the UNFCCC) only cover the former.

Climate resilience: The ability and capacity of a government, business, or community to adapt to climate change by managing associated climate-risks and embracing climate-related opportunities and, in particular, the ability to respond to physical risk and transition risk.

Climate system: Encompasses five interacting components:
– the atmosphere (the air surrounding Earth);
– the hydrosphere (the Earth’s water, including surface water, groundwater, and evaporated water in the atmosphere);
– the cryosphere (snow, ice, and frozen ground on and beneath the Earth’s surface and oceans);
– the lithosphere (the upper layer of the Earth, both oceanic and continental); and
– the biosphere (parts of the Earth and atmosphere where living organisms exist or can exist).

The system evolves based on its own dynamics, and because of external “forcings” such as volcanic eruptions, solar variations, and anthropogenic activities.

COP: Conference of the Parties, which is an annual UN climate change conference attended by the countries that signed the UN Framework Convention on Climate Change, as well as members of the media and representatives of observer organizations.

Decarbonization: The reduction of GHG emissions (particularly emissions of CO₂), typically through reductions associated with electricity, transport, or industry.

Emissions trading or “cap and trade”: A market-based system used as part of mitigation strategies. Within the system, a limit (“cap”) is set on the total amount of GHG emissions from covered installations. Companies buy (through auction) or receive (through permits), emission allowances which they can trade with one another. Those emitting less GHGs than authorized can sell their permits within the system to those emitting more than authorized. Trading systems can exist within companies, or domestically or internationally (e.g., the EU Emissions Trading System).

Fossil fuels: Buried, combustible organic materials formed from decayed plants and animals that have been converted to coal, crude oil, natural gas, or heavy oils through exposure to heat and pressure in the Earth’s crust over millennia.

Greenhouse gas (GHG): Greenhouse gases encompass any gas that absorbs infrared radiation in the atmosphere, which traps heat, and creates the greenhouse effect. Key GHGs include (using common definitions):
– carbon dioxide (CO₂) – which enters the atmosphere through the burning of fossil fuels (coal, natural gas and oil), and breakdown of solid waste and biomass;
– methane (CH₄) – which is emitted during the production and transport of coal, natural gas, and oil, and also results from livestock and other agricultural practices, land use, and decay of organic waste in waste landfills;
– nitrous oxide (N₂O) – which is emitted during agricultural, land use, and industrial activities; combustion of fossil fuels and solid waste; as well as during wastewater treatment; and
– hydrofluorocarbons (HFCs), sulfur hexafluoride (SF₆) and perfluorocarbons (PFCs) – which are synthetic GHGs emitted from a variety of industrial processes.

GHG emissions: GHGs released into the atmosphere through human activities. Direct GHG emissions are within the control of an entity, such the burning of fossil fuels, emissions from industrial processes, or wildfires, while indirect emissions are collateral consequences of activities of a business.

Global mean surface air temperatures (GMST): The estimated global average of near-surface air temperatures over land and sea-ice (i.e., ice found at the sea surface that originated from the freezing of seawater) and of sea surface temperatures over ice-free regions.

Global warming: The IPCC defines global warming as the estimated increase in GMST averaged over a 30-year period, expressed relative to pre-industrial levels, unless otherwise specified. For 30-year periods that cover both past and future years, the current multi-decadal warming trend is assumed to continue.

Intergovernmental Panel on Climate Change (IPCC): An international scientific body established by the United Nations Environment Programme and the World Meteorological Organization to provide policymakers with regular scientific assessments on climate change, its implications, and potential future risks, as well as to put forward adaptation and mitigation options.

International Sustainability Standards Board (ISSB): A newly formed standard-setting body tasked with delivering a comprehensive global baseline of sustainability-related disclosure standards, the International Financial Reporting Standards (IFRS) Sustainability Disclosure Standards.

Low-carbon economy: An economy based on low-GHG emitting power sources with lower output of GHG emissions.

Mitigation: Human intervention to reduce GHG emissions and enhance GHG sinks. Mitigation measures can include phasing out fossil fuels, protecting forests and other carbon sinks, better waste management, and scaling up of renewable energy such as wind and solar.

Net zero: The point at which a country produces no net GHG emissions, typically because it has removed a sufficient level of carbon from the atmosphere to offset the GHG emissions it releases. Net zero targets are also set by local governments, businesses, universities, insurance companies, and investors.

Paris-aligned scenarios: Climate scenarios consistent with limiting the increase in “global average temperatures” to below 2°C above pre-industrial levels and pursuing efforts to limit warming to 1.5°C, as set out in the Paris Agreement. A plan by a party to take climate action (emission-reduction targets, adaptation plans, or other climate action goals) under the Paris Agreement is known as a nationally determined contribution (NDC).

Pre-industrial: According to the IPCC, the pre-industrial era refers to the multi-century period prior to the onset of large-scale industrial activity in 1750. The IPCC chose the reference period 1850–1900 to represent pre-industrial global mean surface temperature.

Renewables: A source of energy that is not depleted by use, such as water, wind, or solar power.

Scope 1-3 GHG emissions: Three methods of measuring GHG emissions along a company’s value chain:
– Scope 1 GHG emissions are direct emissions that occur from sources that are owned or controlled by a business.
– Scope 2 GHG emissions are indirect emissions that occur from the generation of electricity, heat, steam or cooling purchased by, or otherwise brought onto the premises of, a business. These emissions are measured at the source.
– Scope 3 GHG emissions cover all indirect emissions outside Scope 2 that arise in a value chain (both upstream and downstream), such as business travel, purchased goods and services, employee commuting, transportation and distribution of products, solid waste disposal and wastewater treatment.

Sea-level rise: Sea-level rise is an increase in the mean level of the ocean. Sea-level rise can be the result of an increase in the volume of the ocean; it can also increase relative to land, either because of higher volume or land level subsidence, or both. In the context of climate change, most sea level rise is attributed to the ocean’s increased absorption of atmospheric heat and the melting of land-based ice, including glaciers and ice sheets.

Stranded assets: Assets that have suffered from unanticipated or premature write-downs, devaluations, or conversion to liabilities. In short, these are assets whose values have dropped due to external forces, including the effects of climate-related physical risk and/or transition risk. This could be triggered by:
– direct or indirect effects of climate change (across the spectrum of physical risk, from increases in frequency and severity of extreme weather events and sea-level rise, to loss of biodiversity, desertification, land degradation, water scarcity and air pollution);
– Carbon footprint reductions (that is, cutting production to keep carbon emissions within globally accepted “carbon budgets” – the cumulative amount of carbon emissions that can be released (energy sector emissions, together with land use and changes to land use, and industrial emissions) to keep average increases in global temperature to within 2°C above pre-industrial levels);
– Changes in resource availability and shifts in prices of natural resources;
– New regulations (or changes in interpretations of existing regulations) – which could range from direct regulation of carbon by national, supranational (i.e., the European Union) or local authorities, to indirect regulation, such as a limit on water usage or pollution controls;
– Reductions in the cost (and improved price stability) of renewable energy solutions;
– Greater efficiency of trucks, vessels and aircraft that reduce demands for fuel or that reduce the value of older, less efficient trucks, vessels and aircraft;
– The outcome, or threats, of litigation, which could range across a broad spectrum, for example, from actions against upstream or downstream energy operations to actions against commercial property owners;
– Changes in consumer sentiment; or
– Responses to social activist campaigns (changes in societal norms).

United Nations Framework Convention on Climate Change (UNFCCC): One of the two Rio Conventions, it was adopted and opened for signature in 1992 (and entered into force in 1994) with the objective of stabilizing GHG concentrations at a level that would “prevent dangerous anthropogenic interference with the climate system.” The provisions of the UNFCCC are supposed to be implemented through a variety of measures, including the Kyoto Protocol and the Paris Agreement.