42 of the ESS glossary’s terms, each with the part of the syllabus where you first meet it.
An aquatic plant large enough to be seen with the naked eye, growing emergent, submerged or floating in fresh water or shallow coastal water.
A condition caused by a diet supplying the wrong amounts of energy or nutrients, including undernourishment, micronutrient deficiency and overnourishment leading to obesity.
Human-made physical assets used to produce goods and services, such as machinery, tools, buildings and infrastructure.
Land of low agricultural value because of steep slopes, thin or poor soils, low or unreliable rainfall or other limits, where cultivation easily causes degradation.
A group pushed to the edge of society, with little power, wealth or voice in decisions, such as Indigenous peoples, people of a low caste or women farmers.
A period of days to months when sea surface temperatures in an area are unusually high for the time of year, a common trigger of mass coral bleaching.
A clearly defined area of sea or coast managed by law or other effective means to conserve nature, with restrictions on activities such as fishing, which range from partial limits to full protection.
A temperate climate type near oceans, with a small annual temperature range, mild winters, cool summers and precipitation spread throughout the year.
A level descriptor used to mark an extended answer as a whole, matching its overall quality of knowledge, examples, analysis and judgement to a band of marks rather than counting points.
A situation in which the free-market allocation of goods and services is inefficient and reduces society's overall welfare, for example when pollution harms others at no cost to the polluter.
The list of acceptable answers, marking points and rules used by examiners to award marks for a particular question, usually one mark for each valid point up to the total.
An event in which a large proportion of Earth's species, often about three-quarters or more, become extinct within a geologically short time.
The largest harvest that can be taken from a population or trophic level every year without reducing its future availability, equal to its net productivity.
A measure of the centre of a data set, calculated by adding all the values and dividing by the number of values.
The middle value of a data set when the values are arranged in order; with an even number of values, the mean of the two middle values.
An urban area with a population of more than 10 million people.
The size of the holes in a fishing net, which can be regulated so that young, small fish escape and reach breeding age.
A greenhouse gas (CH₄) released by wetlands, ruminant livestock, rice paddies, landfill and fossil fuel leaks; it lasts about 10 years in the atmosphere but traps far more heat per tonne than carbon dioxide.
A solid, ice-like substance in which methane is trapped within a lattice of frozen water, found in permafrost and seabed sediments and stable only when cold and under pressure.
The production of methane by methanogenic microorganisms that break down dead organic matter in anaerobic conditions, for example in wetlands, rice paddies and the stomachs of ruminants.
A restriction on the scope of an investigation's conclusion, arising from the range of data collected, the boundaries of the system studied or the assumptions made.
A flaw in how an investigation was carried out, such as poor control of variables or imprecise measurement, that reduces confidence in the data and conclusion.
A toxic organic compound of mercury that is absorbed easily by living things and becomes concentrated along food chains, damaging the nervous system; the cause of Minamata disease.
Plastic particles smaller than 5 mm, from broken-down plastic items or made small, which are eaten by many organisms and can carry adsorbed pollutants into food chains.
The movement of people from one place to another with the intention of settling there permanently or for a long period, either within a country (internal) or across a border (international).
Regular variations in the shape of the Earth’s orbit, the tilt of its axis and the direction of its axis, which change the distribution of solar radiation and pace glacial–interglacial cycles over tens of thousands of years.
The finely ground waste rock and processing residues left after the valuable mineral has been extracted from an ore, often stored as a wet slurry behind dams in tailings ponds.
A conservation strategy that combines species-based and habitat-based measures, often using a flagship or keystone species to justify protecting a whole habitat.
A farming system that combines growing crops with raising livestock on the same farm, often with crops feeding the animals and manure fertilizing the crops.
The combination of different land uses, such as housing, shops, offices, schools and leisure, in the same neighbourhood or building, so that daily needs can be met within a short distance.
A grazing method in which a large herd is kept on a small paddock for a short time, then moved on, leaving each paddock a long rest to regrow.
The value or category that occurs most often in a data set, most useful for categorical data such as survey answers.
A simplified representation of reality, such as a diagram, graph, equation, simulation or description, used to understand how a system works and to predict its response to change.
A deep, dark, fertile soil of temperate grasslands, with a thick topsoil rich in humus and nutrients, widely used for cereals and grazing.
The growing of a single crop species, often a single variety, over a large area, sometimes for many years in succession.
A seasonal reversal of winds that brings a distinct wet season, as when the ITCZ moves away from the equator in summer and draws moist air over land.
The international treaty, signed in 1987 and in force from 1989, that controls the production, use and trade of CFCs and other ozone-depleting substances; it has been ratified by every UN member state.
The status of an entity whose interests or well-being should be taken into account when deciding how to act, so that it can be wronged by the actions of others.
The fund set up under the Montreal Protocol, financed by developed countries, that pays the extra costs developing countries face in phasing out ozone-depleting substances.
A random change in the base sequence of DNA, which can create a new allele and is the original source of all genetic variation.
A close relationship between two species in which both benefit, such as mycorrhizal fungi exchanging minerals for sugars with plant roots.
Mutualistic associations between fungi and plant roots in which the fungus supplies water and mineral nutrients, especially phosphorus, and the plant supplies sugars.