A systems approach is a holistic way of examining a set of interacting or interdependent components rather than studying each component separately. In IB ESS Subtopic 1.2 Systems, this is core content for both SL and HL, and it is useful because environmental issues involve connected ecological and societal processes.
How a systems approach works
A system has components linked by processes. In a systems diagram, storages are stocks represented by rectangular boxes, while flows are processes represented by arrows showing their direction.
Flows may be transfers, which change the location of matter or energy without changing its form, or transformations, which change its state, chemical nature or energy form. Inputs enter the system, while outputs leave it.
| Systems concept | Meaning and environmental use |
|---|---|
| Storage | A stock, such as water in a lake or carbon in soil |
| Flow | A process connecting storages, such as runoff or decomposition |
| Negative feedback | Counteracts change and helps maintain a stable equilibrium |
| Positive feedback | Amplifies change and may drive the system toward a tipping point |
| Model | Simplifies reality to explain interactions or predict responses |
This approach is useful because changing one component may produce effects elsewhere. For example, diversion of rivers feeding the Aral Sea reduced water storage, increased salinity, damaged fisheries and exposed communities to polluted dust. The issue therefore links hydrology, biodiversity, employment, health and environmental justice.
Systems models also reveal possible intervention points, such as reducing irrigation withdrawals. However, every model involves approximation: greater simplicity improves clarity but reduces accuracy. Stakeholders may also interpret the same system differently because their perspectives and values differ.
Exam technique
For an ESS explain question, identify relevant storages and flows, then show how their interactions produce the outcome. Use precise terms, include feedback where relevant, and avoid the misconception that a systems diagram is merely a labelled picture arrows must represent actual flows, and their directions must be correct.
