The following glossary includes many of the most commonly occurring terms found in the climate change/global warming literature and news media.  It was compiled primarily from the glossaries of the following Websites:

  •       U.S. Global Change Research Program

  •       U.S. Forest Service

In a few cases we simply consulted a dictionary.

For terms not found below, try one of the more detailed Website links cited above.

Term Definition
Adaptation/Adaptive capacity (see also climate resilience) Adjustment in natural or human systems to a new or changing environment. Adaptation to climate change refers to adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities. Adaptive capacity refers to the amount the natural and human systems will be able to adjust to climate change before becoming unstable.
Afforestation, Deforestation and Reforestation Aforestation is the planting of new forests on lands that historically have not contained forests. Deforestation is the conversion of forest to non-forest. Reforestation is the planting of forests on lands that have previously contained forests but that have been converted to some other use.
Alternative energy Energy derived from non-fossil-fuel sources.
Anthropogenic emissions Emissions of greenhouse gasses, greenhouse gas precursors, and aerosols associated with human activities. These include burning of fossil fuels for energy, deforestation, and land-use changes that result in net increase in emissions.
Biodiversity The numbers and relative abundances of different genes (genetic diversity), species, and ecosystems (communities) in a particular area.
Biofuel/bioenergy Fuel produced from dry organic matter or combustible oils produced by plants. Examples of biofuel include alcohol (from fermented sugar), black liquor from the paper manufacturing process, wood, and soybean oil. Bioenergy is energy derived from burning biofuel.
Biomass The total mass of living organisms in a given area or volume.
Carbon capture and storage; Carbon sequestration The process of capturing carbon dioxide and injecting it into locations underground for long-term storage, or sequestering it in biomass (e.g. wood).
Carbon credit A permit that allows an entity to emit a specified amount of greenhouse gases. Also called emission permit. Buying a carbon credit is like building a credit reserve for later withdrawal of some type. One example of a carbon credit is a “cap and trade” program. Under such a program, laws or regulations would limit or ‘cap’ carbon emissions from particular sectors of the economy (or the whole economy) and issue credits (to emit carbon) to match the cap. Entities that emit less carbon and thus have unused credits could then trade (sell) them.
Carbon cycle The term used to describe the flow of carbon (in various forms such as carbon dioxide) through the atmosphere, ocean, or terrestrial biosphere.
Carbon dioxide (CO2) A naturally occurring gas, and also a by-product of burning fossil fuels and biomass, as well as land use changes and other industrial processes. It is the principal anthropogenic greenhouse gas that affects the Earth’s radiative balance.
Carbon footprint The amount of carbon an entity of any type (e.g., person, group, vehicle, event, building, corporation) emits into the atmosphere.
Carbon neutral Being carbon neutral involves calculating your total climate-damaging carbon emissions, reducing them where possible, and then balancing your remaining emissions, often by purchasing a carbon offset.
Carbon pricing/carbon tax Carbon pricing is a method favored by many economists for reducing global-warming emissions—it charges those who emit carbon dioxide (CO2) for their emissions. That charge, called a carbon price, is the amount that must be paid for the right to emit one ton of CO2 into the atmosphere.

A carbon tax is a tax levied on the carbon content of fuels. It is a form of carbon pricing. In terms of mitigating climate change, a carbon tax, which is levied according to the carbon content of fuels, is not a perfect substitute for a direct tax on CO2 itself. The objective of a carbon tax is to reduce the harmful and unfavorable levels of carbon dioxide emissions, thereby decelerating climate change and its negative effects on the environment and human health.

Carbon sink Anything sequestering carbon such as trees and other vegetation, forests, and grasslands.
Carbon source Anything emitting carbon into the atmosphere including forest fires, car exhaust, factories, livestock.
Climate change  A statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use.
Climate justice Climate justice is a term used for framing global warming as an ethical and political issue, rather than one that is purely environmental or physical in nature.
Climate mitigation Measures to reduce the amount and speed of future climate change by reducing emissions of heat-trapping gases or removing carbon dioxide from the atmosphere.
Climate preparedness Actions taken to build, apply, and sustain the capabilities necessary to prevent, protect against, and ameliorate negative effects.
Climate refugees Climate refugees (or climate migrants) are a subset of environmental migrants who were forced to flee due to sudden or gradual alterations in the natural environment related to at least one of three impacts of climate change: sea-level rise, extreme weather events, and drought and water scarcity.
Climate resilience (see also adaptation/adaptive capacity) A capability to anticipate, prepare for, respond to, and recover from significant multi-hazard threats with minimum damage to social well-being, the economy, and the environment.
Desertification Land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities.
Divestment, Divestiture A socially responsible investing tactic to remove assets from a sector or industry based on moral objections to its business practices. It has historical roots in the anti-apartheid movement in South Africa.
Ecosystem A system of interacting living organisms together with their physical environment. The boundaries of what could be called an ecosystem are somewhat arbitrary, depending on the focus of interest or study. Thus, the extent of an ecosystem may range from very small spatial scales to, ultimately, the entire Earth.
Energy service The application of useful energy to tasks desired by the consumer such as transportation, a warm room, or light.
Energy transformation The change from one form of energy, such as the energy embodied in fossil fuels, to another, such as electricity.
Environmental justice The fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies.
External cost Used to define the costs arising from any human activity, when the agent responsible for the activity does not take full account of the impacts on others of his or her actions. Equally, when the impacts are positive and not accounted for in the actions of the agent responsible they are referred to as external benefits. Emissions of particulate pollution from a power station affect the health of people in the vicinity, but this is not often considered, or is given inadequate weight, in private decision making and there is no market for such impacts. Such a phenomenon is referred to as an “externality,” and the costs it imposes are referred to as the external costs.
Extreme weather event An extreme weather event is an event that is rare within its statistical reference distribution at a particular place. Definitions of “rare” vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile. By definition, the characteristics of what is called extreme weather may vary from place to place. An extreme climate event is an average of a number of weather events over a certain period of time, an average which is itself extreme (e.g., rainfall over a season).
Food security When all people at all times have both physical and economic access to sufficient food to meet their dietary needs for a productive and healthy life.
Fossil fuels A natural fuel formed in the geological past from the remains of living organisms.  These include petroleum, coal, and natural gas.
Geoengineering The deliberate and large-scale intervention in the Earth’s climate system, usually with the aim of mitigating the adverse effects of global warming.    Such projects are designed to tackle the effects of climate change directly, usually by removing CO2 from the air or limiting the amount of sunlight reaching the planet’s surface.
Global warming The observed increase in average temperature near the Earth’s surface and in the lowest layer of the atmosphere. In common usage, “global warming” often refers to the warming that has occurred as a result of increased emissions of greenhouse gases from human activities. Global warming is a type of climate change; it can also lead to other changes in climate conditions, such as changes in precipitation patterns.
Greenhouse effect The greenhouse effect is a natural process that warms the Earth’s surface. When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases. The absorbed energy warms the atmosphere and the surface of the Earth. This process maintains the Earth’s temperature at around 33 degrees Celsius (91F) warmer than it would otherwise be, allowing life on Earth to exist. The problem we now face is that human activities – particularly burning fossil fuels (coal, oil and natural gas), agriculture and land clearing – are increasing the concentrations of greenhouse gases. This is the enhanced greenhouse effect, which is contributing to rapid warming of the Earth.
Greenhouse gas Greenhouse gases are 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. Water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and ozone (O3) are the primary greenhouse gases in the Earth’s atmosphere. Moreover there are a number of entirely human-made greenhouse gases in the atmosphere.
Leapfrogging (technology leapfrogging) Leapfrogging (or technological leapfrogging) refers to the opportunities in developing countries to bypass several stages of technology development, historically observed in industrialized countries, and apply the most advanced presently available technologies in the energy and other economic sectors, through investments in technological development and capacity building.
Natural climate solutions Climate change is a global problem, and it requires solutions on a global scale. One of those is hiding in plain sight. Our lands provide an untapped opportunity – proven ways of both storing carbon and reducing carbon emissions in the world’s forests, grasslands and wetlands: “natural climate solutions”.  For example, rather than destroying mangrove forests, swamps or other wetlands to build a residential or commercial development, preserve them and let them serve their natural purpose–to absorb the ebbs and flows of high water from storms without causing harmful flooding.
Permafrost Ground that remains at or below freezing for at least two consecutive years.
Rapid climate change The non-linearity of the climate system may lead to rapid climate change, sometimes called abrupt events or even surprises. Some such abrupt events may be imaginable, such as a dramatic reorganization of the thermohaline circulation (the so-called ocean conveyor belt), rapid deglaciation, or massive melting of permafrost leading to fast changes in the carbon cycle. Others may be truly unexpected, as a consequence of a strong, rapidly changing, forcing of a non-linear system.
Renewable Energy Energy obtained from sources that are, within a short time frame relative to the Earth’s natural cycles, sustainable, and include non-carbon technologies such as solar energy, hydropower, and wind, as well as carbon-neutral technologies such as biomass.
Reservoir  A component of the climate system, other than the atmosphere, which has the capacity to store, accumulate, or release a substance of concern (e.g., carbon, a greenhouse gas, or a precursor). Oceans, soils, and forests are examples of reservoirs of carbon
Sea-level rise An increase in the mean level of the ocean caused by global warming. This rise is primarily driven by two factors: 1) increased volume of seawater due to thermal expansion of the ocean as it warms, and 2) increased mass of water in the ocean due to melting ice from mountain glaciers and the Antarctic and Greenland ice sheets.
Sustainability/ Sustainable development Activities and development that meet the needs of the present without compromising the ability of future generations to meet their own needs.
Urban heat island effect The tendency for higher air temperatures to persist in urban areas as a result of heat absorbed and emitted by buildings and asphalt, tending to make cities warmer than the surrounding countryside.
Water security Reliable availability of water in sufficient quantity and quality to sustain human health, livelihoods, and the environment.


I am of the opinion that my life belongs to the community, and as long as I live, it is my privilege to do for it whatever I can. I want to be thoroughly used up when I die, for the harder I work, the more I live. Life is no ‘brief candle’ to me. It is a sort of splendid torch which I have got hold of for a moment, and I want to make it burn as brightly as possible before handing it on to the future generations.

George Bernard Shaw