136 of the ESS glossary’s terms, each with the part of the syllabus where you first meet it.
A sigmoid growth curve with lag, exponential, transitional and plateau phases, in which population growth slows and levels off at the carrying capacity.
The space between the social foundation and the ecological ceiling of the doughnut model, in which everyone's needs are met without degrading the planet.
The range of conditions within all nine planetary boundaries in which the Earth system is expected to remain in a stable, Holocene-like state that supports human societies.
Drinking water from an improved source that is located on the premises, available when needed and free from faecal and priority chemical contamination; the standard used to monitor SDG 6.
The movement of seawater into a coastal freshwater aquifer, usually because groundwater is pumped out faster than it is recharged, making the water too salty to use.
The build-up of soluble salts in soil, usually when irrigation water or a high water table evaporates near the surface and leaves its salts behind.
The concentration of dissolved salts in water or soil, usually measured in parts per thousand or as electrical conductivity.
The number of individual measurements, sampling units or respondents in a sample; larger samples reduce the effect of random variation and make statistical tests more reliable.
The process of collecting data from a small, representative part of a population or area in order to estimate a characteristic of the whole.
A systematic difference between a sample and the population it represents, caused by the way the sample was chosen, such as placing quadrats by eye.
The coarsest mineral fraction of soil, with particles from 0.05 mm to 2 mm across, mostly quartz; it feels gritty and drains quickly.
The provision of facilities and services for the safe collection, removal, treatment and disposal of human urine and faeces, which protects health and the environment.
An organism, mainly a fungus or bacterium, that feeds by secreting digestive enzymes onto dead organic matter and absorbing the products.
A tropical grassland biome with scattered trees, high temperatures all year and a long dry season, often maintained by fire and grazing as well as climate.
A graph on which each pair of values for two variables is plotted as a single point, used to show whether and how strongly the two variables are related.
An animal that feeds on the dead bodies of animals it has not killed itself, such as a vulture.
A device in the chimney of a power station or factory that removes sulfur dioxide from exhaust gases, usually by passing them through a spray of lime or limestone slurry.
An increase in global mean sea level, caused mainly by thermal expansion of warming sea water and by meltwater from glaciers and ice sheets on land.
The temperature of the water at or near the surface of the ocean, which controls evaporation, storm formation and the exchange of heat between the ocean and the atmosphere.
Any aquatic animal or plant from the sea or from fresh water that people eat, including fish, molluscs, crustaceans and seaweeds.
A flat disc with black and white quarters lowered into water on a marked line; the depth at which it disappears from view measures water clarity.
The physical law that every energy transformation degrades some energy into less useful forms, mainly heat, so no transformation is 100% efficient and entropy increases.
A consumer that feeds on primary consumers and so occupies the third trophic level.
Data collected by someone else and obtained from a published source, such as a government database, a monitoring network or a research paper.
A pollutant that is not emitted directly but forms in the atmosphere when primary pollutants react with each other or with natural components of the air, such as tropospheric ozone.
The rate at which consumers gain biomass from carbon compounds absorbed and assimilated from the food they ingest, per unit area per unit time.
Succession on bare soil where a community existed before but was removed or destroyed, for example abandoned farmland or forest after a severe fire.
The biological stage of sewage treatment, in which aerobic microorganisms break down dissolved and suspended organic matter, greatly reducing biochemical oxygen demand.
A facility that stores seeds, usually dried and frozen, to preserve the genetic diversity of wild plants or crops so that they can be grown again in the future.
Any factor in the environment, such as food supply, predators, disease or climate, that makes some individuals more likely than others to survive and reproduce.
The capacity to have experiences such as pain and pleasure, which some ethicists treat as the condition for having moral standing.
One of the series of communities, or seral stages, that replace each other during succession, from the pioneer community to the climax community.
Wastewater from homes and other buildings, containing human waste, food residues, detergents and other dissolved and suspended material, carried away by drains and sewers.
The process of removing solids, organic matter, nutrients and pathogens from wastewater in primary, secondary and tertiary stages so that the effluent can be released or reused safely.
The number of male births for every 100 female births in a population; about 103–107 occurs naturally, so higher values suggest sex-selective practices.
Reproduction in which gametes from two parents fuse, producing offspring with new combinations of alleles that differ from both parents and from each other.
Radiation of relatively short wavelength, mainly visible light, ultraviolet and near infrared, emitted by the very hot Sun; most passes through the atmosphere without being absorbed by greenhouse gases.
The internationally agreed system of units of measurement, based on units such as the metre, kilogram, second and kelvin, from which derived units such as m², J and kg m⁻³ are built.
A state that has signed an international agreement, showing its intention to be bound and agreeing not to undermine it, but which is not legally bound until it ratifies.
The digits in a number that carry meaning about its precision, counted from the first non-zero digit; 0.0450 has three significant figures and 2,300 usually has two.
The medium mineral fraction of soil, with particles from 0.002 mm to 0.05 mm across; it feels smooth and floury and is easily carried by wind and water.
The management of forests and plantations to grow and harvest trees for timber, fuel and other products.
A measure of species diversity calculated as D = N(N − 1) / Σn(n − 1), which rises with both richness and evenness and has a lowest possible value of 1.
A plastic item designed to be used only once before it is thrown away or recycled, such as carrier bags, drinks bottles, straws, cutlery and food packaging.
A store that takes in more of an element than it releases over a period of time, so that the amount held in it is increasing; a net accumulation.
The present loss of species, caused mainly by human activity, at rates far above the natural background rate, which many scientists argue could match the five past mass extinctions.
A form of shifting cultivation in which forest is cut and burned, cropped for a few seasons, then left as long fallow while vegetation and soil recover.
A gradual environmental change that develops over years or decades, such as sea-level rise, desertification or salinisation of land and water, and slowly undermines livelihoods.
A city that uses sensors, data and digital networks to run services such as energy, transport, water and waste more efficiently, often with apps that help citizens choose low-carbon options.
A system in which a natural ecosystem and a human society are linked so closely, through resource use and management, that each can only be understood together with the other.
The shared, often unwritten rules and expectations of a society or cultural group about how people should behave, which influence individual perspectives and choices.
A mixture of weathered mineral particles, organic matter, water, air and living organisms that forms the loose upper layer of the land surface and supports plant growth.
A material, such as lime, compost or manure, added to soil to improve its structure, pH, water-holding capacity or biological activity.
The set of practices that protect soil from erosion and degradation and maintain its fertility, structure and organic matter.
The decline in a soil's quality and its capacity to support plant growth and ecosystem services, through erosion, salinization, compaction, nutrient loss, acidification or pollution.
The removal of soil particles from one place by wind or water, faster than new soil forms, usually starting with the most fertile topsoil.
The five factors that control how a soil develops: climate, organisms, geomorphology (relief), geology (parent material) and time.
A layer of soil, roughly parallel to the surface, that differs from the layers above and below in colour, texture, organic matter or other properties.
A vertical section through a soil from the surface down to the parent material, showing its sequence of horizons.
An open system in which soil components are stored, gain inputs such as litter and weathered minerals, lose outputs such as eroded and leached material, and undergo transfers and transformations.
The physical make-up of the mineral part of a soil, given by the relative proportions of sand, silt and clay particles.
A triangular diagram that assigns a soil to a texture class, such as loam or silty clay, from its percentages of sand, silt and clay.
A method of producing freshwater in which the sun's energy evaporates salty or dirty water and the vapour is condensed on a cool surface, leaving salts and impurities behind.
Electricity or heat generated from sunlight, either directly by photovoltaic cells or indirectly by concentrating sunlight to heat a fluid that drives a turbine.
The solid waste produced by households, such as food scraps, packaging, paper, glass, metals, plastics and textiles; with similar waste from shops and offices it forms municipal solid waste.
A liquid in which other substances dissolve; water dissolves more substances than any other common liquid because its molecules are polar.
A store that releases more of an element than it takes in over a period of time, so that the amount held in it is decreasing; a net release.
A statistical test that measures the strength and direction of a correlation between two variables by comparing their ranks, without assuming a straight-line relationship.
The formation of new species through evolution, when populations become isolated, adapt differently and eventually can no longer interbreed to produce fertile offspring.
A group of organisms that can interbreed and produce fertile offspring.
The variety of species in a community, which depends on both the number of species present (richness) and how evenly individuals are spread among them (evenness).
A measure of how similar the population sizes of the different species in a community are; a community is even when individuals are spread equally among its species.
The number of different species present in a community or sample.
An approach to conservation that focuses on protecting particular species, usually threatened or charismatic ones, often through ex situ measures, trade controls or species recovery plans.
Discrimination against beings on the basis of the species they belong to, a term popularised by Peter Singer to argue that the suffering of animals deserves equal consideration.
The amount of energy needed to raise the temperature of 1 kg of a substance by 1 °C; for water it is about 4,180 J kg⁻¹ °C⁻¹, which is high.
The movement of adult fish, and of eggs and larvae, from a protected area into neighbouring fished waters, which raises catches outside the protected area.
The religious or sacred meaning that people attach to natural capital, such as a mountain, river or forest regarded as holy or ancestral.
An equilibrium to which a system tends to return after a disturbance, because negative feedback restores its previous state.
A person, group or organisation with an interest in an issue or decision because they affect it or are affected by it, such as residents, companies, governments or NGOs.
A measure of the spread of values around the mean, calculated as the square root of the variance; larger values show more variable data.
A way of writing very large or very small numbers as a number between 1 and 10 multiplied by a power of ten, such as 3.6 × 10⁶ for 3,600,000.
The biomass or number of organisms present in a trophic level or area at one particular time, as opposed to the rate at which it is produced.
The principle that each state has full authority over its own territory and affairs, so no outside body can force it to act without its consent, for example to cut its emissions.
The conclusion that a result is unlikely to have arisen by chance alone, usually because its probability under the null hypothesis is less than 5% (p < 0.05).
An economy in which stocks of capital and population stay roughly constant, maintained by a low, sustainable flow of energy and materials, so it does not grow in physical size.
The condition of an open system in which flows continue but inputs are balanced by outputs, so its storages stay approximately constant over time.
An approach to the environment in which people see themselves as responsible caretakers who manage natural resources carefully for others and for future generations.
The scientific estimation of the size, age structure and productivity of a fish stock, and of how fishing affects it, used to advise on safe catch limits.
A part of a system in which matter or energy is held for a period of time, such as water in a lake or carbon in forest biomass; drawn as a box in systems diagrams.
A graph of a river's discharge over time after a period of rainfall; the delay between peak rainfall and peak discharge is the lag time.
A rise in sea level above the normal tide caused by the strong winds and low pressure of a storm, which can flood low-lying coasts.
The formation of distinct layers in a water body, usually warm, less dense water above cold, denser water, which restricts mixing between them.
A sampling method in which the area is divided into distinct zones and random samples are taken within each zone, usually in proportion to its size.
The layer of the atmosphere from about 12 km to 50 km, in which temperature rises with height because ozone absorbs ultraviolet radiation; it contains the ozone layer.
A proposed geoengineering method that would release reflective particles such as sulfates into the stratosphere so that less sunlight reaches the Earth's surface.
Ozone in the stratosphere, mostly between about 15 km and 35 km (the ozone layer), which absorbs all incoming UVC and most UVB and so protects life at the surface.
The transfer of water along a river or stream channel, downhill towards a lake or the sea.
Growing alternate strips of a row crop and a close-growing crop or grass, often along contours, so that every second strip slows run-off and wind.
A view that natural capital cannot be fully replaced by manufactured or human capital, so critical natural capital must be maintained; shown as the economy nested within society within the environment.
An adaptation to climate change that involves building or changing physical infrastructure, such as flood defences, sea walls, cyclone shelters or desalination plants.
The transformation of ice or snow directly into water vapour, without first melting into liquid water.
A payment or tax reduction from government that lowers the cost of a product or activity, used for example to encourage renewable energy, electric vehicles or insulation.
Farming in which crops or livestock are produced mainly to feed the farming household, with little or no surplus for sale.
The mostly mineral layer (B horizon) beneath the topsoil, with less organic matter, into which clay, iron compounds and nutrients may be washed from above.
The movement of people and activities from dense central areas of a city to lower-density residential areas at its edge.
The replacement of one community by another in an area over time, as each community changes the biotic and abiotic conditions so that others can colonise and outcompete it.
A hazard that develops over hours or days, such as a flood, tropical cyclone or forest fire, and can displace people quickly.
A colourless, acidic gas (SO₂) released mainly when coal, oil and other fuels containing sulfur are burned, and by volcanoes; a primary pollutant and a cause of acid deposition.
A model of a market in which the quantity demanded falls and the quantity supplied rises as price rises, so the price settles where the two quantities are equal.
The underlying ecosystem processes on which all other ecosystem services depend, such as nutrient cycling, soil formation, primary production and the provision of habitat.
The upper layer of a lake or ocean in which wind and waves keep the water well mixed, so that its temperature, oxygen and salinity are nearly uniform.
The transfer of water over the land surface when rain or meltwater cannot infiltrate the ground fast enough, or the ground is already saturated or impermeable.
Fresh water held on the land surface in lakes, rivers, reservoirs, swamps and other wetlands.
The extent to which practices allow for the long-term viability of a system; generally, the responsible maintenance of socio-ecological systems so that conditions are not diminished for future generations.
A measurable quantity, tracked over time, that shows whether a system is moving towards or away from sustainability, such as a biodiversity index, a pollutant concentration or a footprint.
Farming that meets present food needs while maintaining soil fertility, water, biodiversity and farm incomes, so that future generations can continue to farm the land.
Development that meets the needs of the present without compromising the ability of future generations to meet their own needs, as defined by the Brundtland Report in 1987.
A set of 17 social, economic and environmental goals with 169 targets, adopted by all UN member states in 2015, to guide action on sustainability and justice up to 2030.
The amount of a renewable resource that can be harvested per unit time without reducing the stock or its ability to provide the same yield in future.
A strong, wide net swept through long grass or low vegetation to collect insects and other invertebrates.
The formation of new species from populations living in the same area, separated by ecological or behavioural differences rather than a physical barrier.
An interaction between two or more pressures, such as climate change and an invasive species, in which their combined impact is greater than the sum of their separate impacts.
A manufactured fertilizer containing soluble mineral nutrients, mainly nitrogen, phosphorus and potassium, that plants can absorb immediately.
A set of interacting or interdependent components organised to form a functional whole, such as a pond, a forest, a city or the whole Earth.
The real or chosen edge of a system, which decides which flows count as inputs and outputs; often drawn as a dashed line in systems diagrams.
An error that shifts all measurements in the same direction by a similar amount, caused by the equipment, method or observer, and not reduced by repetition.
A sampling method in which samples are taken at regular intervals in space or time, such as every 5 m along a line or at every point of a grid.
A holistic way of visualising and analysing a complex set of interactions, in which a situation is represented as storages linked by flows of energy and matter.
A model of a system in which storages are shown as boxes and flows as labelled arrows pointing in the direction of movement, with inputs and outputs crossing a boundary.
The inner boundary of the doughnut economics model, based on the social goals of the SDGs, below which people lack life's essentials such as food, water, health and political voice.