Bringing about the transformative change to sustainability will succeed only if we understand how systems work and how they interact. When a change is made in one system, we can be almost certain that the changes do not stay within the system but will be reflected to all other connected systems. To make the point, many current problems are unintended side effects of previous, well-meaning system changes: increased use of energy from fossil fuels to power human endeavours has caused the climate change and efforts to increase the yields from agriculture have lead to falling groundwater levels and eutrophication of lakes and rivers.

The Earth is a system that consists of smaller connected systems. The climate system, terrestrial ecosystems and marine ecosystems are all connected and influence each other. Human systems, like the food system and the energy system, have very strong impacts on other systems on the Earth. In fact, it does not make any sense to think about human systems except as parts of the larger Earth system, and we cannot understand the functioning of the climate and the ecosystems without considering the impacts of human systems on them. Currently researchers are increasingly using terms like eco-social, or social-ecological, systems to explicitly underscore the tight linkages between human systems (‘social’) and nature (‘ecological’).

It is easy to grasp why all systems on Earth are intertwined when you realise that the Earth is a closed system: in effect no material enters* nor leaves the Earth system. Only energy in the form of sunlight enters the system, and energy leaves the system as Earth’s own radiation (as we learned in the first part of the course). A small fraction of the Sun’s radiation that falls on Earth fuels the process we know as life.

Photosynthesising organisms, plants and algae, can use sunlight for their own growth. In photosynthesis, energy in the light is converted to chemical energy, and all life on Earth is based on utilisation of this energy (excluding a few deep-sea organisms and bacteria that utilise inorganic chemical energy). Also fossil fuels are a chemical form of sunlight's energy: they are the remains of plants and algae buried under sediments over millions and millions of years.

It is possible to continue dividing the system on Earth to smaller and smaller subsystems. For example ecosystems consist of organisms, which consist of organs, which consist of cells, and all these can be considered as types of systems.

Also human systems can be divided into subsystems in many different ways, as the previous food system example demonstrated. What is essential to understand is that all systems need other systems to function. When any system is modified or altered, it will have impacts on other systems too. Serious attention and consideration of possible harmful impacts is thus essential when considering changes to a system.

Key system properties

Typical for all systems is that they have developed (or have been developed) to serve some purpose. For very simple systems like a car engine the purpose is easy to fathom: the purpose of the engine is to generate power to move the vehicle. For more complex systems, like an ecosystem or the economic system, there is no such obvious and clearly defined purpose, but they are nevertheless important for all the beings that depend on these systems. Humans and other beings need functioning ecosystems to get food and other necessary resources, and the economic system is needed in human societies so that necessary goods and services can be produced and distributed to those who need them. In complex systems, the needs of parties are not the same in kind nor amount, and the system can satisfy (or not) the needs of different parties differently.

For the system to function “appropriately”, it has to be relatively stable, meaning that its function should not show wild perturbations. Consider the human body as a system: it must stay fairly close to 37°C in order to function properly. To maintain the stable state, systems have balancing feedbacks. If the body temperature rises too much, we sweat to cool off. To maintain temperature we need energy, and hunger is a mechanism to ensure sufficient energy intake. Such systems that return to the original state quickly after being perturbed are said to be resilient.

Systems that have been developed for human benefit, like different production systems, are often further developed to increase their efficiency. Efficiency here means that the system produces either more or better “products”, or that the “product” can be produced with smaller inputs of material or human capital (labour). “Product” here must be understood in a broad sense: for example the “product” of the school system are pupils that have grown to be ethically responsible members of the society. The word eco-efficiency on the other hand refers to reduced environmental impacts of the product, for example through reduced greenhouse gas emissions or via the use of recycled materials.

However usually is a trade-off between system efficiency and system stability. A car engine that is not very efficient can serve for decades with minimal repairs, whereas a super-efficient race car engine needs constant maintenance. Increased efficiency can be pursued by reducing overlaps between system parts or by utilizing some parts more efficiently. Increased efficiency however makes the system more vulnerable to disturbances and reduces the ability to recover from them, i.e. it reduces system resilience.

In ecosystems, for example, there are many different species that function in  much the same way: decomposers  decompose dead  material and circulate nutrients, plants photosynthesise and provide nutrition for animals, and so on. In a biodiverse system losing one or two species probably has no detectable effect on the function of the system, for example on the amount of produced biomass. It is however possible to increase the amount of produced biomass by removing all but the most rapidly growing plant species, and increasing the amount of nutrients with fertilisers. These kinds of ecosystems however collapse totally (and so does their productivity) if the climate changes to be unsuitable for the grown plant species, or if a new disease infests the plants, or if the fertiliser is not available.

Making the system more efficient by optimising it to some narrow purpose can cause problems also outside the system. A monoculture optimised for efficient production of biomass reduces the other benefits a biodiverse system could provide: habitats to different species and also many different benefits to humans (were covered  thee in the first part of the course). A system that has been made unstable by excessive intensification increases risks also in other linked systems, for example in the industry that uses the biomass as raw material.

To summarise, in a complex network of interdependent systems, optimising one of the systems without consideration of the whole (so-called sub-optimisation) generally leads to worse outcome for the whole. Here it may be worth noting that in modern human societies, organisations are usually partitioned for the sake of efficiency, for example to economy, justice, politics, religion and education. These subsystems view the society from their restricted point of view, which causes problems with dealing with multifaceted issues, like environmental problems, that do not fall neatly under any single system.

Next we recommend for you to look through a lecture by Donella Meadows on sustainable systems. As you remember, Meadows was an author of the Limits to Growth report by the Club of Rome, and she is one of the best known system scientists in the world. The lecture is from year 1999 (Meadows died in 2001), and the technology used in the lecture does not compare to today's standards. To help you follow the lecture, the text projected to the screen in the beginning of the lecture is reproduced in the box below.

For reflection: think of any system you are familiar with, large or small. What is the purpose of this system? Does the system produce what it is supposed to produce? Is it efficient and stable? You can share your reflections and discuss with other course participants on the page linked below.

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Welcome to the follow-up course!

In the next course on Planetary well-being we will study systems in more detail. We will learn about system properties like thresholds and tipping points,  non-linear responses, alternative stable states and different types of feedbacks. Welcome to the course of Systems and planetary well-being!