62 of the ESS glossary’s terms, each with the part of the syllabus where you first meet it.
A species that reproduces early and produces many small offspring with little parental care, adapted to colonise unstable or new habitats and use short-lived resources.
The change in the Earth’s energy balance, in watts per square metre, caused by a change in a factor such as a greenhouse gas or aerosol since a reference time; positive values cause warming.
Waste containing radioactive isotopes, such as spent nuclear fuel, which emits ionising radiation and must be isolated from people and ecosystems until its radioactivity has decayed to safe levels.
A dry area on the sheltered side of a mountain range, where air that has lost its moisture rising over the mountains descends and warms.
The collection and storage of rain that falls on roofs or other surfaces, so that it can be used for gardens, toilets, livestock, crops or, after treatment, drinking.
An international treaty signed in Ramsar, Iran, in 1971 for the conservation and sustainable use of wetlands, under which parties list wetlands of international importance.
An unpredictable error that scatters measurements above and below the true value; its effect is reduced by repeating measurements and increasing sample size.
A sampling method in which every point in the study area has an equal chance of being chosen, usually by using random numbers as grid coordinates.
A group of 17 metallic elements, the lanthanides plus scandium and yttrium, used in permanent magnets, batteries and electronics, which occur widely but seldom in concentrated deposits.
The amount by which a quantity changes per unit of time or distance, calculated as the change in the quantity divided by the interval over which it changes, such as tonnes per year.
The formal approval of an international agreement by a state, usually through its parliament, after which the state is legally bound by the agreement.
Measurements and observations as they were originally recorded during an investigation, before any calculation or processing.
All forms of nitrogen other than unreactive nitrogen gas (N₂), such as ammonia, ammonium, nitrate and nitrous oxide, which living things can use or which can pollute air and water.
The actual range of conditions and resources in which a species exists, usually smaller than its fundamental niche because of competition and other interactions.
The addition of water to an aquifer or other store, mainly by percolation of rain and snowmelt; the natural input that limits sustainable abstraction.
The collection and reprocessing of waste materials, such as paper, glass, metals and some plastics, into new raw materials or products.
An indicator of the overall extinction risk of a group of species over time, calculated from repeated IUCN Red List assessments; a falling index means species are moving towards extinction.
A coastal bloom of phytoplankton, usually dinoflagellates, dense enough to discolour the water red or brown; many red tides produce toxins harmful to marine life and people.
A UN climate framework for reducing emissions from deforestation and forest degradation, in which developing countries receive results-based payments for proven cuts in forest loss.
A way of studying a situation by breaking it into its separate parts and investigating each part or relationship on its own, often by controlled experiment.
A natural or constructed wetland dominated by reeds through which water flows slowly, used as a buffer zone to remove nutrients, sediment and other pollutants from run-off or wastewater.
The replanting or natural regrowth of forest on land where forest has recently been cleared or degraded.
A fluid that absorbs heat as it evaporates and releases it as it condenses, used in refrigerators and air conditioners; CFCs, HCFCs and HFCs have all been used as refrigerants.
An approach to farming that aims to rebuild soil organic matter, biodiversity and the water cycle, using zero tillage, cover crops, diverse rotations and managed grazing.
An approach to building design that aims for a net positive effect on the environment, for example by generating more energy than the building uses, recharging groundwater or cleaning the air.
An economy designed to work with and within the cycles and limits of the living world, so that materials are reused and ecosystems restored rather than depleted.
A large, rapid and persistent change in the structure and functioning of a system as it moves from one stable state to an alternative stable state.
Ecosystem services that come from the control of natural processes, such as climate regulation by carbon sequestration, flood and erosion control, water purification and pollination.
The release of a species into an area where it once lived but had disappeared, using wild-caught or captive-bred individuals, to re-establish a population.
A situation in which environmental pressure grows more slowly than GDP, so pressure per unit of output falls but total pressure still rises.
The consistency of results, so that repeating the measurements or the whole investigation under the same conditions gives similar values.
A shallow, dark, humus-rich soil formed directly on limestone or chalk, with its topsoil lying on the shattered parent rock.
Energy from sources replenished by natural processes at least as fast as they are used, such as sunlight, wind, tides, flowing water, the Earth’s internal heat and sustainably grown biomass.
A natural resource that can be regenerated or replaced as fast as it is used, through natural growth and reproduction or other recurring natural processes, such as timber, fish and freshwater.
The extent to which an investigation is described in enough detail for another person to carry it out again in the same way and obtain comparable data.
The total fertility rate at which each generation exactly replaces itself, ignoring migration; about 2.1 children per woman where child mortality is low, and higher where it is high.
A repeat of a measurement or treatment under the same conditions, used to show the variation in results and to reduce the effect of random error.
The condition in which two populations no longer interbreed, because of a physical barrier or differences in habitat use, timing or behaviour, so that gene flow between them stops.
A single, precise question that an investigation is designed to answer, naming the variables, the system studied and, where relevant, the place and time.
The planning of a protected area's size, shape, number of parts and connections so that it supports viable populations, for example favouring large, compact and connected reserves.
A natural or artificial lake used to store water, usually behind a dam, so that it can be supplied to people, farms and industry when needed.
The average length of time that an atom of an element, such as carbon, remains in a particular store before moving to another store.
The tendency of an ecological or social system to avoid tipping points and maintain stability; its capacity to resist damage and to recover from, or adapt to, disturbance.
Planning that increases the capacity of an urban system to resist, absorb and recover from shocks such as floods, heatwaves and supply failures, for example through flood-proof buildings and back-up energy.
A collection of maps, graphs, tables, photographs, diagrams and short texts about one previously unseen place or issue, on which every question of an unseen case study paper is based.
The reduction of the stock of a natural resource because it is used faster than it is replaced, which for a renewable resource can lead to collapse.
The ability of a society to ensure the long-term availability of enough natural resources, from its own territory or reliable imports, to meet its demand at an affordable price.
The energy or biomass used in cellular respiration by an organism or trophic level and lost as heat, the R in NP = GP − R.
A waste management strategy that removes waste after it has entered the environment and restores the damaged system, such as clearing beaches or rehabilitating old dump sites.
The use of an item again, for the same or a different purpose, without reprocessing it into a new material, for example refilling a glass bottle or passing on clothes.
A desalination process in which seawater or brackish water is pushed at high pressure through a semi-permeable membrane that lets water molecules through but holds back dissolved salts.
A form of ecological restoration that aims to restore natural processes and self-sustaining ecosystems, for example by reintroducing keystone species, reconnecting habitats and reducing human management.
A legal approach that recognises ecosystems, species or natural features such as rivers as holders of rights, for example to exist, regenerate and be restored, enforceable by guardians on their behalf.
An ethical approach that judges actions by whether they respect the rights of others and fulfil moral duties, regardless of their consequences; also called deontological ethics.
The United Nations Conference on Environment and Development held in Rio de Janeiro in June 1992, which produced Agenda 21 and opened the climate change and biodiversity conventions for signature.
The identification of hazards in an investigation, an estimate of how likely and serious harm would be, and the precautions taken to reduce the risk.
A small swelling on the root of a plant such as a legume or alder that houses nitrogen-fixing bacteria in a mutualistic relationship with the plant.
A circular graph with bars radiating from a centre in the direction they represent, used to show directional data such as wind direction or the orientation of features.
A method of estimating the doubling time of a population by dividing 70 by its annual percentage growth rate.
A plant-eating mammal, such as a cow, sheep or goat, with a multi-chambered stomach in which microorganisms ferment plant material, producing methane.
An area outside towns and cities with low population density and small, dispersed settlements, where most land is used for farming, forestry or other open land.
The movement of people from the countryside to towns and cities, usually within the same country, which is the main cause of urbanisation.