advancing the mitigation of Climate Change and Global Warming through Geoengineering education and research
Glossary of Geoengineering and Climate Change Mitigation Terms and Concepts
Definitions Courtesy Of
- Abrupt climate change — A large-scale change in the climate system that takes place over a few decades or less, persists (or is anticipated to persist) for at least a few decades, and causes substantial disruptions in human and natural systems. (IPCC, 2014).
Aerosol — A suspension of airborne solid or liquid particles, with a typical size between a few nanometres and 10 μm that reside in the atmosphere for at least several hours. For convenience the term aerosol, which includes both the particles and the suspending gas, is often used in this report in its plural form to mean aerosol particles. Aerosols may be of either natural or anthropogenic origin. Aerosols may influence climate in several ways: directly through scattering and absorbing radiation, and indirectly by acting as cloud condensation nuclei or ice nuclei, modifying the optical properties and lifetime of clouds. Atmospheric aerosols, whether natural or anthropogenic, originate from two different pathways: emissions of primary particulate matter (PM), and formation of secondary PM from gaseous precursors. The bulk of aerosols are of natural origin. Some scientists use group labels that refer to the chemical composition, namely: sea salt, organic carbon, black carbon (BC), mineral species (mainly desert dust), sulphate, nitrate, and ammonium. These labels are, however, imperfect as aerosols combine particles to create complex mixtures. See also Short-lived climate pollutants (SLCPs) (IPCC, 2014).
Afforestation — Planting of new forests on lands that historically have not contained forests or converting grasslands or shrublands into tree plantations. Afforestation is sometimes suggested as a tool to sequester carbon, but it can have negative impacts on biodiversity and ecosystem function, for example by reducing runoff and so decreasing water production (IPCC, 2014).
Albedo — The fraction of solar radiation reflected by a surface or object, often expressed as a percentage. Snow-covered surfaces have a high albedo, the albedo of soils ranges from high to low, and vegetation covered surfaces and oceans have a low albedo. The earth’s planetary albedo varies mainly through varying cloudiness, snow, ice, leaf area and land cover changes (IPCC, 2014).
- Anthropogenic — Originating from human activity (IPBES, 2018).
Atmosphere — The gaseous envelope surrounding the earth, divided into five layers — the troposphere which contains half of the earth’s atmosphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere, which is the outer limit of the atmosphere. The dry atmosphere consists almost entirely of nitrogen (78.1 % volume mixing ratio) and oxygen (20.9 % volume mixing ratio), together with a number of trace gases, such as argon (0.93 % volume mixing ratio), helium and radiatively active greenhouse gases (GHGs) such as carbon dioxide (CO2) (0.035 % volume mixing ratio) and ozone (O3). In addition, the atmosphere contains the GHG water vapour (H2O), whose amounts are highly variable but typically around 1 % volume mixing ratio. The atmosphere also contains clouds and aerosols (IPCC, 2014).
- Biochar — Charcoal made from biomass via pyrolysis and used for soil enhancement. Heating biomass with exclusion of air produces a stable carbon-rich co-product (char). The relative benefit of biochar systems is increased if changes in crop yield and soil emissions of methane (CH4) and nitrous oxide (N2O) are taken into account (IPCC, 2014).
Biodiversity — The variability among living organisms from all sources including, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems (IPBES, 2018).
Bioenergy with Carbon Capture and Storage — A future greenhouse gas mitigation technology which produces negative carbon dioxide emissions by combining bioenergy (energy from biomass) use with geologic carbon capture and storage (IPBES, 2018).
- Black carbon — Operationally defined aerosol species based on measurement of light absorption and chemical reactivity and / or thermal stability. It is sometimes referred to as soot. BC is mostly formed by the incomplete combustion of fossil fuels, biofuels, and biomass but it also occurs naturally. It stays in the atmosphere only for days or weeks. It is the most strongly light-absorbing component of particulate matter (PM) and has a warming effect by absorbing heat into the atmosphere and reducing the albedo when deposited on ice or snow (IPCC, 2014).
- Cap-and-trade — An economic policy instrument in which the State sets an overall environmental target (the cap) and assigns environmental impact allowances (or quotas) to actors that they can trade among each other (IPBES, 2018).
- Carbon dioxide (CO2) — A naturally occurring gas, also a by-product of burning fossil fuels from fossil carbon deposits, such as oil, gas and coal, of burning biomass, of land use changes (LUC) and of industrial processes (e. g., cement production). It is the principal anthropogenic greenhouse gas (GHG) that affects the earth’s radiative balance (IPCC, 2014).
- Carbon Dioxide Capture and Storage — A process in which a relatively pure stream of carbon dioxide (CO2) from industrial and energy-related sources is separated (captured), conditioned, compressed, and transported to a storage location for long-term isolation from the atmosphere (IPCC, 2014).
- Carbon Dioxide Removal (CDR) — Carbon Dioxide Removal methods refer to a set of techniques that aim to remove carbon dioxide (CO2) directly from the atmosphere by either (1) increasing natural sinks for carbon or (2) using chemical engineering to remove the CO2, with the intent of reducing the atmospheric CO2 concentration. CDR methods involve the ocean, land, and technical systems, including such methods as iron fertilization, large-scale afforestation, and direct capture of CO2 from the atmosphere using engineered chemical means. Some CDR methods fall under the category of geoengineering (IPCC, 2014).
- Carbon sequestration — The acquisition and long-term storage of carbon in plants, soils, geologic formations, and the ocean. Carbon sequestration occurs both naturally and as a result of anthropogenic activities and typically refers to the storage of carbon that has the immediate potential to become carbon dioxide gas (IPBES, 2018).
Carbon storage — The technological process of capturing waste carbon dioxide from industry or power generation and storing it so that it will not enter the atmosphere (IPBES, 2018).
- Climate — Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system (IPCC, 2014).
- Climate change — Refers to a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods (IPBES, 2018).
- Climate mitigation — A set of actions to limit the magnitude or rate of long-term climate change. Climate change mitigation generally involves reductions in human (anthropogenic) emissions of greenhouse gases (GHGs). Mitigation may also be achieved by increasing the capacity of carbon sinks, e.g., through reforestation. Mitigation policies can substantially reduce the risks associated with human-induced global warming (IPBES, 2018).
Desertification — Desertification is defined as land degradation in arid, semi-arid and dry sub-humid areas (collectively called drylands) because of human activities and climatic variations (IPBES, 2018). Desertification is often caused by poor and unsustainable land management practices that increase soil erosion caused by wind and/or water; the deterioration of the properties of soil; and the reduction of natural vegetation. Desertification can result in the loss of croplands, rangelands and natural ecosystems (IPCC, 2014).
- Direct Air Capture — Chemical process by which a pure carbon dioxide (CO2) stream is produced by capturing CO2 from the ambient air (IPCC, 2014).
- Fossil fuels — Carbon-based fuels from fossil hydrocarbon deposits, including coal, peat, oil, and natural gas (IPCC, 2014).
- Geoengineering — Geoengineering refers to a broad set of methods and technologies that aim to deliberately alter the climate system in order to alleviate the impacts of climate change. Most, but not all, methods seek to either (1) reduce the amount of absorbed solar energy in the climate system (Solar Radiation Management) or (2) increase net carbon sinks from the atmosphere at a scale sufficiently large to alter climate (Carbon Dioxide Removal). Scale and intent are of central importance. Two key characteristics of geoengineering methods of particular concern are that they use or affect the climate system (e. g., atmosphere, land or ocean) globally or regionally and / or could have substantive unintended effects that cross national boundaries. Geoengineering is different from weather modification and ecological engineering, but the boundary can be fuzzy (IPCC, 2012, p. 2) (IPCC, 2014).
- Global warming — Global warming refers to the gradual increase, observed or projected, in global surface temperature, as one of the consequences of radiative forcing caused by anthropogenic emissions (IPCC, 2014).
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- Greenhouse effect — The infrared radiative effect of all infrared-absorbing constituents in the atmosphere. Greenhouse gases (GHGs), clouds, and (to a small extent) aerosols absorb terrestrial radiation emitted by the earth’s surface and elsewhere in the atmosphere. These substances emit infrared radiation in all directions, but, everything else being equal, the net amount emitted to space is normally less than would have been emitted in the absence of these absorbers because of the decline of temperature with altitude in the troposphere and the consequent weakening of emission. An increase in the concentration of GHGs increases the magnitude of this effect; the difference is sometimes called the enhanced greenhouse effect. The change in a GHG concentration because of anthropogenic emissions contributes to an instantaneous radiative forcing. Surface temperature and troposphere warm in response to this forcing, gradually restoring the radiative balance at the top of the atmosphere (IPCC, 2014).
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- Greenhouse Gas — Those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of infrared radiation emitted by the Earth’s surface, the atmosphere, and clouds. This property causes the greenhouse effect (IPBES, 2018).
- Industrial Revolution — A period of rapid industrial growth with far reaching social and economic consequences, beginning in Britain during the second half of the 18th century and spreading to Europe and later to other countries including the United States. The invention of the steam engine was an important trigger of this development. The industrial revolution marks the beginning of a strong increase in the use of fossil fuels and emission of, in particular, fossil carbon dioxide. In this report the terms pre-industrial and industrial refer, somewhat arbitrarily, to the periods before and after 1750, respectively (IPCC, 2014).
- Iron fertilization — Deliberate introduction of iron to the upper ocean intended to enhance biological productivity which can sequester additional atmospheric carbon dioxide (CO2) into the oceans. See also Geoengineering and Carbon Dioxide Removal (CDR) (IPCC, 2014).
Land degradation — The process of putting land in a state where there is a persistent decline or loss of biodiversity and ecosystem functions and services that cannot fully recover unaided (IPBES, 2018).
- Methane (CH4) — One of the six greenhouse gases (GHGs) to be mitigated under the Kyoto Protocol and is the major component of natural gas and associated with all hydrocarbon fuels. Significant emissions occur as a result of animal husbandry and agriculture and their management represents a major mitigation option (IPCC, 2014).
- Mitigation (of climate change) — A human intervention to reduce the sources or enhance the sinks of greenhouse gases (GHGs) (IPCC, 2014).
- Ozone — Ozone, the triatomic form of oxygen (O3), is a gaseous atmospheric constituent. In the troposphere, it is created both naturally and by photochemical reactions involving gases resulting from human activities (smog). Tropospheric O3 acts as a greenhouse gas (GHG). In the stratosphere, it is created by the interaction between solar ultraviolet radiation and molecular oxygen (O2). Stratospheric O3 plays a dominant role in the stratospheric radiative balance. Its concentration is highest in the O3 layer (IPCC, 2014).
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- Radiative forcing — The measurement of the capacity of a gas or other forcing agents to affect that energy balance, thereby contributing to climate change. Put more simply, RF expresses the change in energy in the atmosphere due to GHG emissions (IPBES, 2018).
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- Renewable energy — Energy derived from natural processes (e.g., sunlight and wind) that are replenished at a faster rate than they are consumed. Solar, wind, geothermal, hydro, and some forms of biomass are common sources of renewable energy (IPBES, 2018).
- Restoration — Any intentional activity that initiates or accelerates the recovery of an ecosystem from a degraded state. Active restoration includes a range of human interventions aimed at influencing and accelerating natural successional processes to recover biodiversity ecosystem service provision. Passive restoration includes reliance primarily on natural process of ecological succession to restore degraded ecosystems, but may include measures to protect a site from processes that currently prevent natural recovery (e.g., protection of degraded forests from overgrazing by livestock or unintentional human-induced fire) (IPBES, 2018).
Sequestration — The uptake (i.e., the addition of a substance of concern to a reservoir) of carbon containing substances, in particular carbon dioxide (CO2), in terrestrial or marine reservoirs. Biological sequestration includes direct removal of CO2 from the atmosphere through land-use change (LUC), afforestation, reforestation, revegetation, carbon storage in landfills, and practices that enhance soil carbon in agriculture (cropland management, grazing land management). In parts of the literature, but not in this report, (carbon) sequestration is used to refer to Carbon Dioxide Capture and Storage (CCS) (IPCC, 2014).
- Solar energy — Energy from the sun. Often the phrase is used to mean energy that is captured from solar radiation either as heat, as light that is converted into chemical energy by natural or artificial photosynthesis, or by photovoltaic panels and converted directly into electricity (IPCC, 2014).
- Solar Radiation Management (SRM) — Solar Radiation Management refers to the intentional modification of the earth’s shortwave radiative budget with the aim to reduce climate change according to a given metric (e. g., surface temperature, precipitation, regional impacts, etc.). Artificial injection of stratospheric aerosols and cloud brightening are two examples of SRM techniques. Methods to modify some fast responding elements of the longwave radiative budget (such as cirrus clouds), although not strictly speaking SRM, can be related to SRM. SRM techniques do not fall within the usual definitions of mitigation and adaptation (IPCC, 2012, p. 2). See also Carbon Dioxide Removal (CDR) and Geoengineering (IPCC, 2014).
- Stratosphere — The highly stratified region of the atmosphere above the troposphere extending from about 10 km (ranging from 9 km at high latitudes to 16 km in the tropics on average) to about 50 km altitude (IPCC, 2014).
- Sustainability — A characteristic or state whereby the needs of the present and local population can be met without compromising the ability of future generations or populations in other locations to meet their needs (IPBES, 2018).
- Tillage — In agriculture, the preparation of soil for planting and the cultivation of soil after planting (IPBES, 2018).
- Troposphere — The lowest part of the atmosphere, from the surface to about 10 km in altitude at mid-latitudes (ranging from 9 km at high latitudes to 16 km in the tropics on average), where clouds and weather phenomena occur. In the troposphere, temperatures generally decrease with height (IPCC, 2014).
- Urban heat island effect — The term “heat island” describes built up areas that are hotter than nearby rural areas (IPBES, 2018).
Water security — The capacity of a population to safeguard sustainable access to adequate quantities of and acceptable quality water for sustaining livelihoods, human well-being, and socio-economic development, for ensuring protection against water-borne pollution, water-related disasters, and for preserving ecosystems (IPBES, 2018).
Wind energy — Kinetic energy from air currents arising from uneven heating of the earth’s surface. A wind turbine is a rotating machine for converting the kinetic energy of the wind to mechanical shaft energy to generate electricity. A windmill has oblique vanes or sails and the mechanical power obtained is mostly used directly, for example, for water pumping. A wind farm, wind project, or wind power plant is a group of wind turbines interconnected to a common utility system through a system of transformers, distribution lines, and (usually) one substation (IPCC, 2014).
