15 August 2024
This is the third of a series of posts on complexity. We’ll be exploring some of the ways that studying complex systems gives us a more nuanced way of understanding the world, how this is relevant to all our lives, and the unique contributions we can make to this new way of understanding the world from Aotearoa New Zealand.
We’ve all been there. Someone steps up to a microphone to speak, and there’s a little high-pitched ringing around the edges of their voice through the speakers. In a flash, this has become a loud squeal. Jolted in their seats, the audience clasp their hands to their ears until the person with the best reflexes manages to leap across to turn down the volume.
This is feedback. A microphone placed too close to a speaker picks up the sound from the speaker and amplifies it, then sends it back out of the same speaker. The microphone now picks up the louder sound, and amplifies it further. This reinforcing feedback happens rapidly, and before long we’re being assaulted by a high-pitched squeal.
We can also imagine a thermostat in a room. We set a preferred temperature, and allow the heating to run until this temperature is reached. At that point, the thermostat switches off the heating, and the room slowly cools. This is balancing feedback. Once the room has cooled below the set temperature, the heating is switched back on.
Feedback is all around us
Feedbacks are processes that change the thing that caused them.
Let’s say that we have a system with two parts: A and B. A is connected to B by one process, and B is connected to A by another. If the state of A changes, it triggers a corresponding change of some amount in B, because they are connected. But now, B has been modified, and because it is also connected to A by a second process, the change in B also results in further change to A.
The processes connecting A to B, and B to A, are both feedbacks, and those feedbacks can be reinforcing or balancing. Audio feedback and thermostats are classic examples of these two types of feedback. A reinforcing feedback drives further change in the direction a process was already going. It is a self-sustaining, or amplifying, feedback, which can lead to exponential growth or decline. A balancing feedback, on the other hand, leads to a reversal in the direction of change. So something that was increasing starts to decrease, and vice versa, which can lead to stability or equilibrium.
The concept of feedback is key to understanding complex systems in reality, reaching well beyond the scales of the examples of audio feedback or temperature control. Systems of feedback determine patterns we can see in the world around us. These patterns can be observed over time within any complex system, whether that be from the perspective of the earth sciences, biology, how cities work, or human health.
When we observe these dynamic patterns, whether it is exponential growth (like a virus spreading) or collapse (like the Wall Street crash of 1929) or even if a system is in a state of seeming stability, it is useful to explore the feedback processes behind these patterns. It is through understanding feedback that deep insight into fundamental causes and how to make change can be found.
Reinforcing and balancing feedback on a global scale
In studying the climate we can see reinforcing and balancing feedbacks playing out on a global scale. We know the release of carbon dioxide from burning fossil fuels results in more longwave radiation being trapped in our atmosphere, which leads to warming. This warming melts sea ice and thaws permafrost. Which in turn lead to further warming, which leads to more melting, and so on. This is reinforcing feedback, just like the squeal of a microphone.
Like the way a thermostat works, rainfall is an illustration of balancing feedback. Evaporating moisture from the surface of the Earth leads to increasing water vapour in the air. This increasing humidity then makes it harder for further water to evaporate from the land or ocean. Eventually, as the air becomes saturated, it rains, humidity is reduced, evaporation resumes, and the whole cycle starts again.
Feedbacks between people and environments
There are destructive inevitabilities, such as the increase in extreme weather events, of planetary system feedbacks like warming caused by too much carbon dioxide. But there are also constructive feedbacks where relationships between people, our practices and culture, and the built and natural environments are leading to new and innovative solutions.
One helpful reinforcing loop in the area of energy, where increasing demand for solar and wind power is driving down the cost of these clean energy sources so that they become more affordable for households.
In transport, if we can understand feedback processes underpinning car dependence, we can shift from reliance on cars to more people walking, wheeling and biking. For example, we know that fewer people ride bikes when they associate them with negative experiences of car danger and injury. If traffic on busy streets is slowed and road space is allocated to bike lanes, more and more people become visible, and you will see more people riding different kinds of bikes. When people see others like themselves on bikes having fun while getting around, this is a reinforcing feedback as they feel inspired and encouraged to then give it a go.
The ways we adapt to a changing climate bring new feedback processes into play. When people’s homes and land are threatened by severe weather, flooding, sea level rise and coastal erosion, balancing feedback responses – such as the construction of sea walls – might successfully buffer a worsening crisis in the short-term. But adaptations may not be sufficient in the long term and may in fact cause greater harm through attracting further housing development and therefore increasing the number of people exposed to climate dangers.
Understanding feedback is essential for finding solutions
Identifying and understanding processes of feedback is critical to understanding the complex causes behind the issues that we face. If we understand feedback, we can find more appropriate and sophisticated solutions, and become aware of dangers and unintended consequences. If researchers and policymakers incorporate feedback in their methods and practices, we can create more effective pathways of action that result in beneficial outcomes.
In the next post in this series on the foundations of complex systems, we’ll be taking a look at how we can understand phenomena across different scales in order to intervene more effectively.
A collaboration between Te Pūnaha Matatini Principal Investigators Alex Macmillan and Nick Golledge, and illustrator Hanna Breurkes. Edited by Jonathan Burgess.