Syllabus Edition
First teaching 2024
First exams 2026
The Systems Approach (DP IB Environmental Systems & Societies (ESS))
Revision Note
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
The Systems Approach
A systems approach is the term used to describe a method of simplifying and understanding a complicated set of interactions
Systems and the interactions they contain can be environmental or ecological (e.g. the water cycle or predator-prey relationships), social (e.g. how we live and work) or economic (e.g. financial transactions or business deals)
There are two ways of studying systems:
A reductionist approach means breaking a system down into its parts and studying each one individually
This can be useful for studying specific interactions in detail but it doesn't show what's going on in the system as a whole
A holistic approach looks at all of the system's processes and interactions as a whole
For example, sustainability or sustainable development depends on a highly complex set of interactions between many different factors
These include environmental, social and economic factors (sometimes referred to as the three pillars of sustainability).
A systems approach is required in order to understand how these different factors combine and interact with one another, as well as how they all work together as a whole (the holistic approach)
Components & Interactions in Systems
Storage and flow
A system is comprised of storages and flows
The flows provide inputs and outputs of energy and matter
The flows are processes that may be either:
Transfers
Transformations
Transfers and transformations
These are two fundamental concepts in systems (and systems diagrams) that help to understand how matter and energy move through a system
Transfers are the movement of matter or energy from one component of the system to another without any change in form or quality
For example, water flowing from a river to a lake is a transfer
Transformations, on the other hand, involve a change in the form or quality of matter or energy as it moves through the system
For example, when sunlight is absorbed by plants, it is transformed into chemical energy through the process of photosynthesis
Transfers and transformations are often represented in systems diagrams by arrows that connect the different components of the system
Arrows that represent transfers are usually labelled with the quantity of matter or energy being transferred (e.g., kg of carbon, kJ of energy), while arrows that represent transformations may include additional information about the process involved (e.g., photosynthesis, respiration)
Systems diagrams can help identify the key transfers and transformations that occur within a system and how they are interconnected
By understanding these processes, it is possible to identify opportunities to improve the efficiency or sustainability of the system
Transfers and transformations can occur at different scales within a system, from the molecular level to the global level
For example, at the molecular level, nutrients are transferred between individual organisms, while at the global level, energy is transferred between different biomes
Systems diagrams
Systems are often represented as simplified diagrams made up of storages and flows
Storages are commonly drawn as shapes with defined boundaries (such as a circle or rectangle)
Flows are commonly drawn as arrows
These arrows represent the various inputs and outputs occurring within a system
The size of the shapes and arrows can be representative of the size of the particular storage or flow (although often they are not drawn this way)
Emergent properties
The interactions within a system, when looked at as a whole, produce the emergent properties of the system
Emergent properties are properties of a system that appear as individual system components interact; the components themselves do not have these properties
For example, in an ecosystem, all the different ecological interactions occurring within it shape how that ecosystem looks and behaves
If the interactions change for some reason (e.g. a new predator is introduced), then the emergent properties of the ecosystem will change too
Predator–prey cycles and trophic cascades are good examples of emergent properties, where patterns of change occur that would not occur in the isolated components
Examiner Tips and Tricks
In your exam, you may be asked to create a system diagram representing the storages and flows, inputs and outputs of a particular system (usually a relatively simple lab-based or natural system). Unless the question specifically asks otherwise, you can normally keep your boxes and arrows the same size.
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