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What is a regime shift?
We define regime shifts as large, persistent changes in the structure and function of social-ecological systems, with substantive impacts on the suite of ecosystem services provided by these systems. Better understanding of regime shifts is important as they may have substantial impacts on human economies, societies and well-being, and are often difficult to anticipate and costly to reverse.
How do regime shifts work?
Different regimes can be metaphorically represented by a ball-and-cup diagram. The valleys or cups represent different regimes or fundamental ways in which the system can function and be structured. A regime shift entails a shift in the current system state (represented as a ball) from one cup or valley to another. While in a particular regime, it is important to note that the system does not remain stable but fluctuates around.
Regime shifts result from a change in the dominant feedbacks. All complex systems contain many feedback loops, but these can typically evolve and combine in only a limited number of ways. Over time, a particular combination of feedbacks will tend to become dominant, leading the system to self-organize into a particular structure and function – or "regime". However, if the system experiences a large shock (eg a volcano) or persistent directional change (eg accumulation of pollutants, habitat loss) the dominant feedbacks may be overwhelmed or eroded. At some point a critical threshold may be passed where a different set of feedbacks become dominant, and the system experiences a large, often abrupt change in structure and function – or a "regime shift".
Further reading
Biggs R, Blenckner T, Folke C, Gordon L, Norström A, Nyström M & Peterson GD. 2011. Regime Shifts. In: Sourcebook in Theoretical Ecology. Hastings A & Gross L (eds). University of California Press, Berkeley.
May RM, Levin SA, Sugihara G. 2008. Ecology for Bankers. Nature 451, 893-895.
Scheffer M. 2009. Critical transitions in Nature and Society. Princeton University Press.
Scheffer M, Carpenter SR, Foley JA, Folke C & Walker BH. 2001. Catastrophic shifts in ecosystems. Nature 413, 591-596.
Online resources:
Regime Shifts: What are they and why do they matter? http://www.regimeshifts.org/datasets-resources/details/15/26
Wikipedia: http://en.wikipedia.org/wiki/Regime_shift
Resilience Alliance Thresholds Database: http://www.resalliance.org/index.php/thresholds_database
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