2.1. Basics of system function

A good way to understand how systems work is to look at what the system produces (output) and what it needs to function (input). For example, consider a school whose purpose is to teach students the knowledge and skills they need. The learning of pupils is therefore the desired product of the school system.

The school itself, of course, consists of a large number of smaller systems, such as the school building and its maintenance, the systems needed for school meals, and so on. To function, a school therefore needs at least pupils, teachers and other staff, a school building and teaching materials.

The school system's internal activities (process) teach students the subjects defined in the curriculum. The curriculum is therefore also a necessary input to the school's functioning, and is itself a product of another system - the National Board of Education. In the school process, pupils progress from one grade level to the next, once they have learnt what the curriculum assigns to their grade level, and eventually leave the school system.

In a school, the different parts of the system - such as the people who work there - interact with each other. These effects mean changes in the state of the parts of the system. Through the teacher's actions, the knowledge and skills of the pupils are built up. The activities of the catering staff enable pupils and teachers to do their work. 

Of course, there are also unplanned interactions between people in a school that affect the way things function. For example, learning can be hindered by disruptive behaviour in lessons or bullying. School, like any other system, does not always work perfectly and is not isolated from external influences.

Stocks, flows and balancing feedbacks

Systems are often modelled as stocks and flows. Stocks can be matter, energy or information, and the size of the stock in a system depends on the inflows and outflows. For example, a school's teaching staff can be thought of as a stock, the size of which at any given point in time is the result of past teacher recruitment (inflow) and retirements and resignations (outflow).

In a well functioning system, information about the system's stocks is transmitted within the system in such a way that the system is able to regulate itself. For example, if it is known that teachers are retiring or switching to other jobs, new teachers are recruited, or if a student is identified as having learning difficulties, tutoring is provided. In well-functioning systems, the system is also proactive, adapting to future changes well in advance. If the search for a new teacher were to start only when a class was missing a teacher, functioning of the school system would be severely disrupted.

Mechanisms that seek to keep the system in balance are called balancing feedbacks. A change in the stock - or knowledge of a future change - triggers a mechanism that returns the system to a state that is conducive to its functioning. The process thus starts from the state of the system and ends up there, hence the name "feedback".

As mentioned above, the size of the system's stocks is affected by both inflow and outflow, so the size of the stock can be adjusted by changing the inflow, outflow or both. For example, if there is too little money in a bank account, the amount of money in the account can be increased by increasing income, decreasing expenditure, or by affecting both income and expenditure.

If the mechanisms regulating the system do not work or are not efficient enough, the balance and functioning of the system will be disrupted. Climate change is an example of a disruption where the regulatory mechanism is unable to restore the system to equilibrium. Before the industrial revolution, the amount of carbon dioxide released into the atmosphere and the amount of carbon dioxide leaving the atmosphere were roughly equal: plants and decaying bedrock absorbed as much carbon dioxide as decaying biomass and volcanoes emitted. The atmospheric carbon dioxide content thus remained relatively stable for about 10 000 years.

The use of fossil fuels increases the amount of carbon dioxide released into the atmosphere. In 2021, anthropogenic emissions, mostly from fossil fuels but also from land use, accounted for about 5% of total atmospheric carbon dioxide emissions. The majority of CO2 emissions therefore come from natural systems.

Increased atmospheric carbon dioxide levels increase the growth of plants and algae, and thus the removal of carbon dioxide from the atmosphere. However, this increased growth only sequesters about half of the increase in anthropogenic emissions; the other half remains in the atmosphere. The inefficiency of the regulatory mechanism in relation to the increase in emissions has led to a 45% increase in atmospheric CO2 concentration compared to pre-industrial times (1850: 287 ppm; 2021: 416 ppm). 

To mitigate climate change, efforts are now being made to develop technological solutions that remove carbon dioxide from the atmosphere and store it in the layers of the Earth's crust. Let's compare the atmosphere to a bathtub, where more water is constantly flowing into it than is leaving through the drainage hole (the plug has already been removed). It is now obvious that the tub is overflowing. You may wonder which is probably the more effective solution in this situation: to pump water out of the drain hole at a faster rate, or to turn the tap down? 

Of course, from a climate change perspective, it would make the most sense to turn off the tap. But societies' dependence on abundant and cheap energy has prevented this. When the tap cannot be turned off and the bathtub overflows, measures that are not efficient but are more readily acceptable may also seem sensible.

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