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Critical transitions are abrupt shifts in the state of
Significant efforts have been made to identify early-warning signals of critical transitions.Scheffer, M., et al. (2009) Early-warning signals for critical transitions. ''Nature'' 461, 53–59Dakos, V., et al. (2008) Slowing down as an early warning signal for
ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s, the climate
Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...
, financial system
A financial system is a system that allows the exchange of funds between financial market participants such as lenders, investors, and borrowers. Financial systems operate at national and global levels. Financial institutions consist of complex, c ...
s or other complex
Complex commonly refers to:
* Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe
** Complex system, a system composed of many components which may interact with each ...
dynamical systems
In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water in a p ...
that may occur when changing conditions pass a critical or bifurcation point
Bifurcation theory is the Mathematics, mathematical study of changes in the qualitative or topological structure of a given family of curves, such as the integral curves of a family of vector fields, and the solutions of a family of differential e ...
. As such, they are a particular type of regime shift
Regime shifts are large, abrupt, persistent changes in the structure and function of ecosystems, the climate, financial systems or other complex systems.Lewontin, R. (1969) Meaning of Stability. ''Brookhaven Sym Biol'', 13Holling, C.S. (1973) Resil ...
. Recovery from such shifts may require more than a simple return to the conditions at which a transition occurred, a phenomenon called hysteresis
Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of ...
.
Early-warning signals and critical slowing down
Significant efforts have been made to identify early-warning signals of critical transitions.Scheffer, M., et al. (2009) Early-warning signals for critical transitions. ''Nature'' 461, 53–59Dakos, V., et al. (2008) Slowing down as an early warning signal for abrupt climate change
An abrupt climate change occurs when the climate system is forced to transition at a rate that is determined by the climate system energy-balance, and which is more rapid than the rate of change of the external forcing, though it may include sud ...
. ''P Natl Acad Sci Usa'' 105, 14308–14312van Nes, E.H., and Scheffer, M. (2007) Slow recovery from perturbations as a generic indicator of a nearby catastrophic shift. ''Am. Nat.'' 169, 738–747Hastings, A., and Wysham, D.B. (2010) Regime shifts in ecological systems can occur with no warning. ''Ecol Lett'', 1–9 Systems approaching a bifurcation point show a characteristic behaviour called critical slowing down leading to an increasingly slow recovery from perturbations. This, in turn, may lead to an increase in (spatial or temporal) autocorrelation and variance, while variance spectra tend to lower frequencies, and the 'direction of critical slowing down' in a system's state space may be indicative of a system's future state when delayed negative feedbacks leading to oscillatory or other complex dynamics are weak. Researchers have explored early-warning signals in lakes, climate dynamics, the Amazon rainforest,
* News article about the study: forests worldwide,
* News article: food webs, dry-land transitions and epilepsy attacks.
Studies show that more than three-quarters of Amazon rainforest has been losing resilience since the early 2000s as measured by CSD and that tropical, arid and temperate forests are substantially losing resilience. It has been proposed that a loss of resilience in forests "can be detected from the increased temporal autocorrelation (TAC) in the state of the system, reflecting a decline in recovery rates due to the critical slowing down (CSD) of system processes that occur at thresholds".
See also
*Tipping points in the climate system
In climate science, a tipping point is a critical threshold that, when crossed, leads to large and often irreversible changes in the climate system. If tipping points are crossed, they are likely to have severe impacts on human society. Tippin ...
* Deforestation and climate change
Deforestation is a primary contributor to climate change. Land use changes, especially in the form of deforestation, are the second largest anthropogenic source of atmospheric carbon dioxide emissions, after fossil fuel combustion. Greenho ...
* Ecological resilience
In ecology, resilience is the capacity of an ecosystem to respond to a perturbation or disturbance by resisting damage and recovering quickly. Such perturbations and disturbances can include stochastic events such as fires, flooding, windstorms ...
* Ecological threshold
Ecological threshold is the point at which a relatively small change or disturbance in external conditions causes a rapid change in an ecosystem. When an ecological threshold has been passed, the ecosystem may no longer be able to return to its st ...
* Ecosystem collapse
An ecosystem is considered collapsed when its unique biotic (characteristic biota) or abiotic features are lost from all previous occurrences. Ecosystem collapse causes ecological collapse within a system; essentially altering its stability, re ...
* Cascade effect (ecology)
An ecological cascade effect is a series of secondary extinctions that are triggered by the primary extinction of a key species in an ecosystem. Secondary extinctions are likely to occur when the threatened species are: dependent on a few specific ...
* Percolation theory
In statistical physics and mathematics, percolation theory describes the behavior of a network when nodes or links are added. This is a geometric type of phase transition, since at a critical fraction of addition the network of small, disconnected ...
References
External links
* * {{Cite news , date=2022-09-08 , title=Climate change: Six tipping points 'likely' to be crossed , language=en-GB , work=BBC News , url=https://www.bbc.com/news/science-environment-62838627 Systems theory