Appendix 1: Glossary

Term	Definition
Abruptness	A change in a system that is faster than the factors forcing it.
Agency	The capacity of an agent (human or non-human) to act in a given environment.
Agent	A person, organisation or organism that takes an active role in a system.
Anomie	A state of a society or community characterised by a breakdown of social norms, social ties and social reality, resulting in social disorder and disorientation, mental health deterioration, increased suicide rates, and/or increased deviant behaviour.
Attractor	A state or set of states towards which a system tends to evolve for a wide range of initial conditions (or perturbations away from the attractor).
Bi-stability	Property of some systems whereby they exhibit two stable states or attractors under the same external conditions. This is a special case of multi-stability.
Bifurcation point	Where a system moves from one stable state/attractor to a different one under a small change in boundary conditions (where a small change in a parameter in a differential equation leads to a qualitative change in the long-time solution).
Bifurcation tipping	Where a small change in forcing causes a multi-stable system to undergo a catastrophic bifurcation and move into a qualitatively different state/attractor.
Cascade effect	A causal chain whereby a small change in a system triggers a further change in another system and so on, resulting in a large overall change across systems. Synonymous with chain reaction and domino effect. (Sharpe, 2023).
Catastrophic bifurcation	Where a system moves discontinuously from one stable state/attractor to another at the crossing of a bifurcation point.
Climate	The mean state of the weather, typically averaged over 30 years.
Climate colonialism	The deepening or expanding of domination of less powerful countries and peoples through initiatives that intensify foreign exploitation of poorer nations’ resources or undermine the sovereignty of native and Indigenous communities in the course of responding to the climate crisis.
Climate system	The parts of the Earth system that govern the climate at the surface of the Earth.
Complex system	A system consisting of a large number of interconnected components that interact with each other, making its behaviour difficult to predict.
Complex adaptive system	A complex system that has the ability to change in response to changing (internal or external) conditions in a way that maintains or enhances its function.
Contagion	The spread of a particular phenomenon or behaviour through a population or network of agents. In simple contagion, the phenomenon/behaviour is assumed to spread on contact with a single agent, as in disease epidemiology; in complex contagion, spreading requires multiple contacts with multiple agents (Centola, 2018).
Counterfactual	A statement or proposition that expresses what might have happened if something that did not actually happen had occurred. It is a way of describing a hypothetical situation that contradicts what actually happened in the past or what is happening in the present.
Critical mass	A type of tipping point in a social system where one more person adopting a behaviour or technology causes everybody else to adopt.
Critical slowing down	A phenomenon in which the rate (speed) at which a system recovers from small disturbances slows down before a tipping point. This characteristic is exploited to create early indicators of tipping (~see Early indicator).
Critical transition	An abrupt shift in a system that occurs at a specific (critical) threshold in external conditions.
Demand-side solution	Solutions that reduce GHG emissions and other harmful stressors by changing consumption habits, norms and lifestyles; as opposed to supply-side solutions that focus on technologies.
Diffusion of innovation	The process whereby new ideas, products or services spread through social systems over time, often following a non-linear, S-shaped trajectory (Rogers, 1962).
Early indicator/ Early warning signal/ Early opportunity indicator	A statistical indicator that a system is moving towards a tipping point, usually due to critical slowing down. This is termed an early warning signal prior to an undesirable tipping point (usually in a biophysical system) and an early opportunity indicator prior to a desirable, positive tipping point, signalling an opportunity to intervene to trigger it.
Earth system	The complex system at the surface of the planet Earth, comprising the atmosphere, hydrosphere (including oceans and freshwaters), cryosphere (including ice sheets), biosphere (living organisms), and lithosphere (land, soils, sediments, and parts of the Earth’s crust).
Earth system tipping point	Tipping point in the Earth system.
Ecological tipping point	Tipping point in a population, community or ecosystem.
Ecosystem	An ecological system consisting of living organisms coupled to their physical and chemical environment.
Emergent property	Property of a complex system that cannot be reduced to the properties of its component parts because it also depends on their interactions.
Enabling conditions	System conditions (for example price, or population size) that can allow a positive tipping point to be triggered.
Feedback (mechanism or loop)	A closed-loop of causality within a system whereby an initial change feeds back to amplify or dampen that change. Feedbacks can be mathematically positive or negative.
Green sacrifice zones	Ecologies, places and populations that will be severely affected by the sourcing, transportation, installation and operation of solutions for powering low-carbon transitions, as well as end-of-life treatment of related material waste.
Human systems	Complex, often adaptive, systems created by humans. They are embedded in, and interact with, the Earth system. Human systems can be divided into domains such as socio-behavioural, technological, political and economic. Human and Earth systems are often defined together as coupled systems (e.g. social-ecological-technological) to emphasise their interconnection. Also called social systems.
Hysteresis	The dependence of a system’s current state on its history, such that, when forced in one direction, it may pass a tipping point from one stable state to another, but when the forcing is reversed it must be reduced further until a different tipping point is reached to return to the initial state.
Irreversibility	A change in a system that is not reversed under the same boundary conditions that triggered it, or that takes significantly longer to recover from than the time it took to reach.
Leverage point	A place to intervene in a system such that a small input can have a large beneficial effect (Meadows, 1999).
Multi-stability	Property of some systems whereby they exhibit multiple stable states or attractors under the same boundary conditions.
Negative/damping /balancing feedback	Feedback that dampens/counteracts an initial change.
Negative tipping point	A tipping point that is predominantly detrimental to humans and the natural systems we rely on.
Negative social tipping point	A negative tipping point in a human (social) system that leads, for example, to a financial collapse, political radicalisation or conflict.
Noise	Stochastic variability that a system is subject to.
Noise-induced tipping	Where a multi-stable system is tipped out of its present state (or attractor) into an alternative state (or attractor) by a perturbation.
Non-linearity	Any situation where a change in output is not proportional to a change in input.
Path dependence	Any situation where past events constrain future events.
Percolation	Phenomenon that occurs when adding or activating nodes or links in a network, whereby the network abruptly becomes globally connected, allowing change to spread throughout (whereas before, change was locally contained).
Positive/amplifying /reinforcing feedback	Feedback that amplifies/reinforces an initial change.
Positive tipping point	A predominantly beneficial tipping point. Specifically, one that accelerates change which a) reduces the likelihood of negative Earth system tipping points, and/or b) increases the likelihood of achieving just social foundations, both of which are needed to secure a sustainable future for all (Rockström et al., 2023; Gupta et al., 2023; Raworth, 2017). Sometimes referred to as a ‘social tipping point’.
Qualitative change	Change in the qualities of a system, which can mean the appearance or disappearance of important features and change in the balance of feedback. Sometimes quantifiable as change that is (much) larger than the standard deviation of a system’s normal variability. Where non-quantifiable, a qualitative change is a judgement based on ontological, epistemological and normative subjectivity (Tàbara et al., 2021; Milkoreit et al., 2018; Lenton el., 2008).
Rate-induced tipping	When the rate of forcing of a system is faster than the force that restores it to steady state, causing it to leave that state/attractor and undergo a qualitative (irreversible or reversible) change.
Regime shift	A shift in a system state from one stable state to another. Regime shifts are often large, sudden and long-lasting (Biggs, 2009). Where used in this report, we define on a case-by-case basis.
Resilience	The capacity of a system to resist (or deal with) change and continue to function in its present state. In quantitative analyses, resilience is often defined as the capacity of a system to return to a stable state/attractor after a perturbation, measured as its recovery rate from disturbance.
Self-perpetuation	Change in a system that continues even if forcing is removed until a new state is reached. Synonymous with self-sustained change.
Sensitive intervention point	A place to intervene to help trigger positive tipping points in human systems (Mealy et al., 2023). Similar to “Leverage point”.
Social system	See “Human systems”.
Social tipping intervention	An intervention leading to a small change in forcing that has a big, normatively ‘positive’ effect on a crucial human (social) system feature (Otto et al., 2020).
Social tipping point	Tipping point in a human (social) system, which can have a predominantly beneficial (positive social tipping point) or harmful (negative social tipping point) effect (Winkelmann et al., 2022).
Social-ecological system	A coupled system including human (e.g. cities, land-uses, economies) and ecological (e.g. oceans, forests, soils) components.
Social-ecological tipping point	A tipping point that arises because of the coupling of the social and ecological components of a system.
Socio-behavioural system	A human system that encompasses social norms, behaviours and lifestyles, communities and their cultures, and institutions.
Socio-technical system	A system consisting of multiple elements of human systems including actors, organisations, technologies, markets, practices, infrastructures, policies and supply chains (Köhler et al., 2019).
Socio-technical tipping point	A tipping point that arises because of the coupling of the social and technological components of a system.
Social-ecological-technological system	A complex adaptive system composed of interacting social, ecological and technological components.
Social-ecological-technological tipping point	A tipping point that arises because of the coupling of the social, ecological and technological components of a system.
Stable state	A state that a system will return to for some range of initial conditions or perturbations away from that state. Stability is maintained by negative feedback loops that resist change.
Strategic intervention	A deliberate input into a system designed to have maximum impact by influencing the enabling conditions, reinforcing feedbacks and/or trigger for a positive tipping point.
Super-leverage point	A strategic intervention capable of catalysing tipping cascades across multiple systems (Meldrum et al., 2023).
Supply-side solution	Solutions that reduce greenhouse gas emissions and other harmful stressors with technological innovation; as opposed to demand-side solutions that focus on consumption habits, norms and lifestyles.
Sustainability	An aggregate measure of the Earth’s biophysical capacities (planetary boundaries) and social foundations that ensure a minimum level of wellbeing for a given population, indefinitely.
System	A group of interacting or interrelated things that act according to a shared set of rules to form a recognisable, unified whole.
Threshold	The point or level at which a physical effect begins to be produced. A tipping point involves a threshold but thresholds are a much broader class of phenomena.
Tipping cascade	Where passing one tipping point triggers at least one other tipping point.
Tipping dynamics	The changes in a system over time that result from crossing a tipping point.
Tipping element	Originally introduced to describe large parts of the climate system (greater than ~1000km length scale) that could pass a tipping point (Lenton et al., 2008). Also used more broadly to describe a part or subsystem of a larger system that can pass a tipping point.
Tipping event	The crossing of a tipping point.
Tipping point	Occurs when change in part of a system becomes self-perpetuating beyond some threshold, leading to substantial, widespread, often abrupt and irreversible, impacts.
Tipping system	A system that can cross a tipping point.
Transformation	The process of rapid and fundamental change of social-ecological-technological systems needed for humanity to secure a sustainable future (Patterson et al., 2017).
Transition	A process of managed, often sector-specific, socio-technical change.
Trigger	A change that causes a system to pass a tipping point.

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