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Anthropocene
The 'Anthropocene' is a term widely used since its coining by Paul Crutzen and Eugene Stoermer in 2000 to denote the present time interval, in which many geologically significant conditions and processes are profoundly altered by human activities. These include changes in: erosion and sediment transport associated with a variety of anthropogenic processes, including colonisation, agriculture, urbanisation and global warming; the chemical composition of the atmosphere, oceans and soils, with significant anthropogenic perturbations of the cycles of elements such as carbon, nitrogen, phosphorus and various metals; environmental conditions generated by these perturbations — these include global warming, ocean acidification and spreading oceanic 'dead zones'; the biosphere both on land and in the sea, as a result of habitat loss, predation, species invasions and the physical and chemical changes noted above.
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Equilibrium
A situation in which processes that affect the state of a system precisely balance out so that the system does not change. An equilibrium is 'stable' if the system returns to it after a small perturbation and is 'unstable' if the system moves away from the equilibrium point after such a perturbation.
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Feedback loop
Set of cause-effect relationships that form a closed loop.
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Overexploitation
Exploitation (or harvest or consumption) at a rate that compromises the overall productivity of the exploited population.
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Positive feedback
A chain of effects through which something has a positive effect on itself. For instance, climate warming in some regions may cause snowmelt. The dark vegetation thus uncovered absorbs more solar radiation than the snow, and this leads to further warming.
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Regime shift
A relatively sharp change from one regime to a contrasting one, where a regime is a dynamic "state" of a system with its characteristic chaotic fluctuations and/or cycles.
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Resilience
The magnitude of disturbance that a system can tolerate before it shifts into a different state. The capacity of a system to absorb disturbance and reorganize while undergoing change so as to still retain essentially the same function, structure, identity and feedbacks.
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Resistance
Force needed to cause a certain change in a system.
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Runaway change
Change that is accelerating and self-propelling due to a positive feedback.
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Threshold
A point where the system is very sensitive to changing conditions.
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