IB ESS HL 1.2.9 Stable Equilibrium Question Bank

'Steady state equilibrium' is a concept relevant to many systems. Justify its usefulness in understanding the sustainability of named systems.

Answers may demonstrate:
- understanding concepts \& terminology of steady state equilibrium; short

term oscillations; long-term stability; systems approach; holistic view; open/closed systems; storages; flows; balanced inputs \& outputs; balanced processes (transfers \& transformations); laws of thermodynamics; tipping points; stable equilibrium; negative \& positive feedback; ecosystem resilience; sustainable development definition; life-supporting services; food webs; population dynamics; S curve; carrying capacity; cycles of matter; flow of energy; mean global temperature; natural income; natural capital; MSY (maximum sustainable yield); environmental/social/economic sustainability;
- breadth in addressing the concept of steady state equilibrium (SSE) as applied to a range of natural and/or anthropogenic systems and linking to how this concept contributes to understanding sustainability as the quest of human societies to achieve long-term stability (meeting the need of future generations), despite inevitable short-term fluctuations in the process of meeting present needs.
- examples of different steady state equilibria occurring in a range of natural \& anthropogenic systems, e.g. predator-prey cycles, fluctuation around carrying capacity, disturbance-prone ecosystems, nutrient cycling, timber harvesting, fisheries, crop/meat production, energy use, water extraction, etc. or unsustainable examples deviating from SSE; e.g. deforestation, overfishing, global climate change, pollution, habitat loss, overconsumption etc..
- balanced analysis providing evidence supporting the idea that the concept of 'steady state equilibrium' is useful in understanding how various aspects of sustainability may be achieved in a range of systems. [Note to examiners: not how equilibrium is achieved in sustainable systems or how unsustainable systems deviate from equilibrium/balance. Still, such examples are implicitly linked to the context of the question].
- a conclusion that is consistent with, and supported by analysis and examples given e.g. Steady state equilibrium is inherent in the sustainable management and responsible use of natural capital. Short-term fluctuations are inevitable, as, for example, catching fish at a rate observing MSY, reduces temporarily the population, but soon it will regenerate through reproduction. Understanding that the important issue is to maintain the long-term stability of natural capital would help achieving sustainability of a system like wild fisheries.

Please see markbands on page 23.