The glossary of Systems Thinking terms and concepts shown on this page is based on a document originally developed in 2016 by Gilbert, Gross, and Kreutz for the InTeGrate platform. Lisa Gilbert created a modified newer version in conjunction with David Laviska and the American Chemical Society Green Chemistry Institute in 2024. The document provided below has been further edited and expanded by Alisha Szozda, Jane Wissinger and KCVS for posting here on the SaSTICE website.
The list of terms and concepts is restricted to what the authors determined the most essential entries, and the definitions/explanations provided are intentionally brief. More information can be found at the following additional sources:
A balancing, or negative, feedback loop diminishes the effect of disturbances. It works to balance flux between two or more components and moves a system toward equilibrium.
A boundary shows the limit or edge of a closed system; a boundary separates a system and the surrounding environment.
A box model (also known as dynamic systems model or stock and flow model) is a graphical and quantitative representation of a system, where components and fluxes are given values and followed through time.
Causation describes how a change in one component of a system affects another. A “causal loop” is similar to a “feedback loop” and represents relationships between components of a system.
See Forcing
Closed System
A closed system retains matter and energy, preventing it from being exchanged with the external environment.
Component
A component is an individual part of a system that combines with other components to make a larger whole; it can be a reservoir, an attribute of a system, or a subsystem.
Couplings are links between system components; they can be either positive (a change in one component causes a change in the same direction in the linked component) or negative (change in one component stimulates a change of the opposite direction in the linked component).
A cycle represents constant movement of material from one component to another.
A disturbance represents an applied change (e.g., increase or decrease) to one or more components of a system.
See Forcing
The dynamics of a system can be understood as the behaviour that describes how a system, or component of a system, acts over time based on circular, interconnected cause/effect relationships.
See Box Model
See Response
Emergent properties arise from the interactive behavior of a system as a whole and represent the cumulative product of the actions and interactions of the collective components of a system. Emergent properties may or may not be predictable from the individual properties of system components.
The environment represents all the components of the surroundings in which a system is located. The environment can exist outside system boundaries.
Systems in a state of stable equilibrium tend to reestablish equilibrium after experiencing disturbances. In this case, disturbances from equilibrium will be followed by system responses (including negative feedback loops) that return the system to its equilibrium state. This is also called “homeostasis” or “dynamic equilibrium”. Systems with an unstable state of equilibrium respond to disturbances with positive feedback loops and move further from equilibrium.
Feedback loops are self-perpetuating mechanisms of change and their subsequent response(s) to that change.They involve a cyclical process where the output of the system is circled back and used as input to either amplify the effect of the disturbance (positive) or diminish the effects of the disturbance (negative).
See Flux
Flux, or flow, is a quantitative term that describes the rate of matter or energy movement (amount per unit time) to or from a system component. The term “transfer” is also sometimes used to describe this concept.
Forcing is a persistent disturbance of a system. Terms such as “driver” and “cause” can also be used to describe this disturbance.
The rate of matter or energy movement (flux) into a system component.
Interconnections are the relationships between components of a system that allow that system to function; they hold the system together and reveal how the manipulation of one component can affect another or even the entire system.
A leverage point represents a component of a system that can be targeted for disturbance (by external forces/actors) to achieve a desired or predicted outcome.
Material stewardship is the responsible management of materials throughout their entire lifecycle (from extraction to disposal) to minimize their environmental impact and support sustainability.
A negative, or balancing, feedback loop diminishes the effect of disturbances. It works to balance flux between two or more components and moves a system toward equilibrium.
An open system allows for the exchange of material and/or energy between itself and the environment.
Flux out of a system component.
A temporary disturbance of a system.
See Reservoir
A positive, or reinforcing, feedback loop amplifies the effect of disturbances, moving the system away from equilibrium.
Reductionism can be thought of as the opposite of systems thinking. It is an approach to understanding complex systems that involves breaking down a system into its individual components and assessing them as isolated entities.
A reinforcing, or positive, feedback loop amplifies the effect of disturbances and moves the system away from equilibrium.
A system component that contains matter or energy. The terms “pool,” “storage,” and “stock” are also used to describe this component.
The average length of time a matter or energy remains in a given reservoir.
A response, or effect, denotes the change in a system resulting from a disturbance, perturbation, or forcing.
If the flux of matter or energy into a component is greater than the flux out of the component, then that component is defined as a sink.
A SOCME, or System-Oriented Concept Map Extension, is a way to visualize the components and interactions of a system using a concept map. A “system” can be thought of as any collection of components that interact with each other. SOCMEs also group concepts into subsystems, which help to define the system, its boundaries, and promote systems thinking.
SOCME diagrams were first introduced in 2019, in an article in the journal Nature Sustainability (Mahaffy, P. G., Matlin, S. A., Holme, T. A., MacKellar. J. (2019) Systems thinking for educating about the molecular basis of sustainability. Nature Sustainability, 2, 362-370. https://doi.org/10.1038/s41893-019-0285-3).
If the flux of matter or energy out of a reservoir is greater than the flux into the reservoir, then that reservoir is defined as a source.
A system is at steady state when there is no change in any component or source/sink in that system measured as a function of time. (Note: A system at steady state is not necessarily in a state of equilibrium.)
See Reservoir
See Box Model
See Reservoir
Sustainability can be understood as meeting the needs of the current global population without compromising the ability of future generations to meet theirs.
A system is an entity composed of diverse but interrelated parts or components that function as a complex whole.
A systems diagram or map is a graphical representation of a system, showing system components and couplings.
Systems thinking can be thought of as the opposite of reductionism. It is a holistic approach to understanding complex systems that involves acknowledging the intricacies of connections, counterbalances, and synergies between system components and thinking broadly about context, related systems/subsystems, flows into/out of the system, and the surrounding environment. A systems thinking approach recognizes that individual components of a system cannot be isolated without affecting the properties of the system as a whole.
A threshold is the level or value at which a rapid change in the system state, often from one equilibrium state to another, occurs. Threshold can also be referred to as a tipping point.
See Threshold
See Flux
A vicious cycle is a reinforcing Feedback Loop with an emerging harmful or negative result: two or more components of a system act to intensify each other and lead to a worsening situation.
A virtuous cycle is a reinforcing Feedback Loop with an emerging helpful or positive result: two or more components of a system act to intensify each other and lead to an improving situation.