Embedded Files
Helpful prior learning and learning objectives
Helpful prior learning and learning objectives
Helpful prior learning:
Section 1.1.1 The economy and you which explains what an economy is and how it is relevant to students’ lives
Section 1.1.2 The embedded economy, which explains the relationship between the economy and society and Earth’s systems.
Section S.1 What are systems?, which explains what a system is, the importance of systems boundaries, the difference between open and closed systems and the importance of systems thinking
Section S.2 Systems thinking patterns, which outlines the core components of systems thinking: distinctions (thing/other), systems (part/whole), relationships (action/reaction), and perspectives (point/view)
Section S.3 Systems diagrams and models, which explains the systems thinking in some familiar information tools as well as the symbols used to represent parts/wholes, relationships and perspectives.
Learning objectives:
Distinguish between reinforcing and balancing feedback in systems
Explain how reinforcing and balancing feedback creates patterns of behaviour in systems
Explain how reinforcing feedback can lead to tipping points that trigger a change in system state
Diagram causal loops with feedback for a variety of economic, social and ecological systems
When we act, we get reactions from family, friends, colleagues and neighbours. These reactions are feedback, information that comes back to us and helps us make changes to our behaviour or our work to achieve our goals, improve our relationships, knowledge and skills. For example, when you cook a meal for friends or family, they might tell you what they liked and didn’t like. This information helps you cook an even better meal next time. The information from others feeds back into your future actions to cause a change—hopefully better tasting food!
Figure 1. We get feedback from other people every day, like facial expressions that let us know how others feel about something we did.
(Credit: Gajus, licensed with Adobe Stock)
What are causal connections?
What are causal connections?
If you have covered Section S.2 on systems thinking patterns, then you know that systems contain parts that are distinguished from one another. Parts of systems are also related to one another. These relationships influence how the entire system behaves.
A causal connection shows how one part of a system affects another; it is a relationship. For example, water evaporating off of leaves of trees in the Amazon Rainforest cools and condenses in the atmosphere to form clouds (Figure 2). These clouds release rain that increases the soil moisture that encourages more trees to grow, creating even more evaporation, clouds and rain. Each step influences the next, creating a chain of cause and effect (Figure 3). Understanding these causal connections helps us see how changes in one part of a system ripple through the whole system, sometimes in surprising ways.
Figure 2. Satellite image of clouds forming over the Amazon Rainforest as the land warms, water evaporates off the leaves, and the rising and cooling air condenses to form clouds
(Credit: Nasa Earth Observatory, public domain)
Figure 3. Causal connections between some parts of a rainforest system. Notice how rainfall affects trees in a loop, but we could also identify other causal connections from rainfall. Can you think of any?
What are feedback loops and why do they matter?
What are feedback loops and why do they matter?
The example in Figure 3 shows that causal connections can create feedback loops. A feedback loop is where a change in one part of a system affects another part, which then loops back to influence the original part of the system. Feedback loops come in two main types: reinforcing and balancing.
Reinforcing Feedback
Reinforcing feedback pushes a system further in the same direction. The feedback in Figure 3 is an example of reinforcing feedback, because an increase in rainfall leads to more trees. This reinforcing feedback is why rainforests are able to produce their own rain.
Another example is the melting of polar ice due to climate change. When ice melts in polar regions, the water is darker than the surrounding ice sheet, and absorbs more sunlight than the white ice did. This warms the area, melting even more ice—a reinforcing loop. Figure 4 shows a satellite image of this happening on the Greenland ice sheet.
Figure 4. Warming in the polar regions melts ice which results in further warming, a reinforcing feedback loop. Use the handle in the middle to see the change. (Credit: NASA, public domain)
Reinforcing feedback also appears in social systems. For example, a motivated student might work harder. Teachers are more likely to support a hard working student, and this support can boost student motivation even further. Conversely, a struggling student may lack motivation, and then receive less support from teachers, which damages their motivation even more, creating a downward spiral.
Balancing feedback
Balancing feedback occurs when a change in the system triggers a reaction in the system in the opposite direction. Balancing feedback helps keep a system stable because changes to the system are countered by opposite or balancing forces.
Think of your body temperature. If you get too hot, you sweat. The sweat evaporates off your skin to cool you (Figure 5). If you get too cold, you shiver, warming you up. This balancing process doesn’t mean no change in your body temperature, but that there are actions and reactions that keep the temperature around a stable level at about 37°C or 98.6°F. This is called a dynamic equilibrium.
Figure 5. When your body temperature rises, you sweat. This helps bring your body temperature back to normal levels in dynamic equilibrium.
(Credit: Kamus Production, Pexels licence)
Another example is predator-prey relationships. A predator is an animal that consumes another animal, its prey, for food. Deer are prey for wolves. When deer populations increase, wolves have more food, so their numbers also increase. As more wolves hunt the deer, the deer population decreases. Fewer deer mean fewer wolves, and the cycle continues. Negative feedback in the ecosystem ensures that both the deer and wolf populations stay within a certain range. The oscillating lines (Figure 6) around a stable number in a behaviour-over-time graph (Section S.3) are typical of systems with balancing feedback.
Figure 6. The populations of wolves and deer change over time, but around a stable number due to the negative feedback of the predator- prey relationship.
What are tipping points?
What are tipping points?
Feedback loops explain certain kinds of system behaviour. Balancing feedback loops help systems remain stable, like the human body or ecosystems. Reinforcing feedback loops can lead to rapid changes in one direction, for better or worse.
A tipping point is when a system experiences so much change in one direction through reinforcing feedback that it shifts the system into a completely new state (Figure 7). If you have ever seen someone tip backwards on two legs of a chair, you know what a tipping point looks like. At first, they can keep their balance as they lean back. But if they lean too far, past the tipping point, they’ll fall backwards to the floor. This is a new stable state.
Figure 7. As a system is pushed more and more in one direction (from A to B), the system could reach a tipping point (B), where even a small nudge pushes it over the edge and into a new state (C) that may be very difficult or impossible to reverse. A person tipping back in a chair illustrates the same process.
(Credit: Beyond the Roadmap Report)
To return to our ice melt example, if global warming causes enough ice to melt (Figure 4), the reflective ice surface disappears, and the area heats up even faster. At some point, the system tips. The ice sheet won’t be able to recover because too much ice has melted and the area of dark, heat absorbing areas of land and water will be too large. Scientists are already seeing evidence of this in Greenland, where melting ice reveals ever-larger areas of barren rock, vegetation and wetlands.
Social systems also have tipping points. Rising economic inequality creates discontent with political and economic systems. There may be widespread protests, increased support for radical political parties or even a revolution. At the time of writing this section in early 2025, this kind of social and political instability seems to be on the rise in many parts of the world. What a social tipping point might look like in this case is unclear.
How can we diagram causal connections and feedback loops?
How can we diagram causal connections and feedback loops?
Connection circles
Connection circles are a helpful first step to figure out which things, factors, variables, concepts or other items are involved in the system and how important they are.
Draw a circle on a piece of paper, a flip chart, or a board.
Identify 5-10 key parts of the system—these parts should:
Be important to changes in the system.
Be something that can increase or decrease.
Be described with a noun (e.g., "tree growth," "rainfall," "evaporation").
Write these parts around the circle
Find cause-and-effect relationships. Which elements directly cause others to increase or decrease? Draw an arrow from the cause to the effect. The relationships can be based on data or an informed hypothesis.
Label each connection to show whether the part increases or decreases the other part.
If both parts move in the same direction (when one increases, the other increases OR when one decreases, the other decreases), mark the arrow with a "+". This is called a direct relationship.
If the parts move in opposite directions (when one increases, the other decreases OR when one decreases, the other increases), mark the arrow with a "–". This is called an inverse relationship.
Look for feedback loops. If a series of cause-and-effect relationships forms a closed loop, this is a feedback loop, which can help explain patterns in the system. Reinforcing feedback loops are marked with an R and balancing feedback loops are marked with a B. Sometimes there are also curved arrows around the R or B to help the reader see which direction to read the relationships.
Figure 8 shows a connection circle using the parts from the rainforest first described in Figure 3 with six additional parts to increase the complexity. Talk through some connections between parts with a partner if you can, to make sure you understand the connections and symbols.
Note: the red question mark on the temperature-trees relationship is because to a certain point warmer temperatures can increase tree growth. But if temperatures rise too much, trees become stressed and die. So how you label this relationship and what it means for the other feedback loops in this connection circle depends on your assumptions about the current temperature state.
Figure 8. A connection circle can help you see the variables in a system, how they influence each other, and which highly connected variables may be most important for changing the system.
Finding feedback loops
Now, see if you can find the feedback loop illustrated in Figure 3. Start with ‘trees’ and follow the arrows, talking through the relationships until you get back to trees again. Click the arrow to see the feedback loop highlighted in the diagram and labeled with an R to indicate reinforcing feedback.
Click the arrow to see the feedback loop highlighted in the diagram and labeled with an R to indicate reinforcing feedback.
Click the arrow to see the feedback loop highlighted in the diagram and labeled with an R to indicate reinforcing feedback.
Figure 9. Some connections in this connection circle have been lightened to make the darker reinforcing feedback loop more visible.
Most often, causal loops are not presented in connection circles, but are shown in the format of Figure 10. If there are significant delays in the effect, then the symbol ‘||’ is added to the line. In Figure 10 a delay has been added to the relationship between soil moisture and trees, since tree growth is slow.
Connection circles can also help you identify parts of a system that have a particularly large impact on the system because they have so many connections to other parts. When you see that many connecting arrows start from one part, this indicates that the part is particularly important, a leverage point discussed further in Section S.8. In Figure 8, ‘trees’ has more connections than the others, which indicates that it has a large impact on the system.
Figure 10. Causal loops are usually represented like this, rather than remaining in the connection circle. Notice that only some of the elements of the system are included here to show the loop, but more factors from the connection circle could be added.
Stock and flow + causal loops with feedback
It is possible to combine stock and flow diagrams (Section S.4) with causal loops. The situation with glacier ice on a mountain would look like Figure 11. Snow is an inflow that adds to the stock of polar ice. Ice melt is the outflow that reduces the stock of polar ice. Ice melt is affected by temperature, shown as an arrow pointing at the symbol for rate of ice melt outflow.
Rising global temperatures increase the ice melt, causing a larger outflow from the polar ice stocks. As the polar ice stock decreases, heat absorption of the region increases because there is more melted water and less reflective ice, causing even more outflow from the glacier ice stock. If the amount of snow remains the same, we will see less and less ice in the stock over time. This is happening on the Greenland ice sheet (Figure 4) and in mountain glaciers all over the world.
Figure 11. A stock and flow diagram of glacier ice, showing a positive (reinforcing) feedback loop that amplifies ice melt over time
Causal loops and feedback shape system behaviour, either reinforcing change or maintaining stability. Reinforcing feedback accelerates trends, sometimes triggering tipping points with sudden, irreversible shifts. Balancing feedback regulates systems, preventing extremes. Recognising these dynamics helps us understand financial crises, ecosystems, and climate change. Mapping causal links reveals leverage points for informed action (Section S.8) supporting resilience and regeneration.
Activity S.5
Activity S.5
Concept: Systems
Skills: Thinking skills (transfer) and communication skills
Time: 30-40 minutes
Type: Individual, pairs or group
Option 1: Causal loop diagram practice
Time: 30-40 minutes
Read the following examples of feedback in human systems and ecosystems. For each one, draw a causal loop diagram with feedback. Be sure to include:
the parts
arrows to show the direction of influence of the relationships
+ or - signs to show a direct or indirect (inverse) relationship between the two variables
indicate whether the overall loop shows balancing or reinforcing feedback. Use the symbols B and R (with or without curved arrows) to show this, as was explained earlier in this section.
Note: your causal loop diagrams may not be exactly the same as those shown here. You may have more or fewer variables, or different names for them. This is fine, as long as the overall causal relationships show an accurate positive or negative feedback loop. If in doubt, discuss with another student or your teacher.
Global warming and polar ice
As global temperatures increase, polar ice melts, exposing darker ocean water. This dark water absorbs more sunlight/heat, raising temperatures further and causing more ice to melt.
Once you have your loop, how would you add CO2 emissions to the diagram? Where would it go?
Wealth and income
Wealth is the total value of assets such as money, house, or investments. Many of these assets generate income, such as when people rent out apartments they own. This income increases wealth further, enabling the purchase of even more income-generating assets.
This feedback loop increases economic inequality over time. How could you add economic inequality to the diagram?
Demand and supply in a market
When demand for a product increases, its price tends to increase. When prices rise, supply of the product tends to increase. As supply increases, prices often decrease.
Note: diagramming this requires two connected causal loops. Before you draw it, consider what connects the two loops?
Jevons paradox
More and more material resources are used to create goods and services. As a result, concerns about resource use increase, and businesses find ways to become more efficient, lowering the amount of resources used.
But higher efficiency also lowers business production costs, which enables businesses to increase output. Lower consumer prices cause more demand for products, also leading to more output. Higher output requires more resource use.
Option 2: Savings and interest - Combining stock/ flow and causal loops
Time: 5-10 minutes
In the activity for Section S.4, one question asked you to draw a stock and flow diagram for a savings account, showing deposits and interest as inflows and withdrawals and fees as outflows.
There is feedback in this system, because the amount of interest you earn on the money in your savings account depends on the interest rate, represented by the rate control on the interest flow in Figure 16 below. At any given interest rate, the more savings you have, the more interest you earn.
Figure 16. Stock and flow diagram for money in a savings account
Add this feedback loop to Figure 16 by drawing the system diagram on a piece of paper or whiteboard, or pasting it into a digital document to annotate. Click the arrow to see an answer.
Option 3: Making a causal loop diagram from article information, or a local issue
Time: 35-40 minutes
For this activity, you can either use the article Soil degradation and its consequences (click arrow to see article), or you can identify a local issue in your class, school, neighbourhood, or city/town.
With a partner or small group if possible, create a connection circle from the article or discuss the issue you have chosen.
Identify no more than 8-10 parts of the system and connect them with arrows and +/- signs as appropriate.
Identify possible feedback loops in the connection circle.
Create a causal loop diagram with feedback loops from the information in the connection circle.
Use the causal loop diagram to tell the story of soil degradation, or your local issue, to another group or a partner if you worked individually.
How were your causal loops similar and different (if you used the article)? OR Did other groups have ideas about missing elements in your systems diagram (if you worked on a local issue)?
Soil degradation and its consequences
As the global population grows and food choices change with higher incomes, soil degradation becomes a serious threat to food production and ecosystems. Industrial farming methods, designed to increase crop yields, now contribute to the very problem they were meant to solve.
Modern farming relies on heavy machinery, chemical fertilisers, and pesticides to boost production. These practices temporarily increase yields but also weaken the soil. Fertilisers provide nutrients, but they do not replace organic matter, which is essential for healthy soil. Pesticides harm soil organisms that help maintain fertility. Frequent ploughing and monocropping further deplete nutrients and break down soil structure.
Over time, degraded soil loses its ability to retain water and nutrients. As soil fertility declines, crop yields drop. To compensate, farmers use even more fertilisers and pesticides, intensify tillage, or expand farming into new areas. These actions accelerate soil degradation, creating a reinforcing feedback loop where each step worsens the next.
Soil degradation also affects the climate. When soil breaks down, it releases stored carbon into the atmosphere, contributing to global warming. In turn, climate change causes more extreme weather, such as droughts and heavy rains, which further damage soil. This creates another reinforcing feedback loop, making soil degradation and climate instability worse over time.
To stop this cycle, farmers and policymakers need to adopt sustainable practices. Methods such as crop rotation, agroforestry, and reduced tillage help restore soil health. Protecting soil is not only essential for food security but also for stabilising the climate and supporting ecosystems.
Struggling with the Option 3 activity? Click below for some ideas or to check your own
System parts
Soil fertility – The soil's ability to support plant growth
Crop yields – The amount of food produced per hectare
Fertiliser and pesticide use – The amount of synthetic inputs used to boost production
Tillage (plowing) – The frequency and intensity of soil disturbance
Organic matter in soil – Decomposed plant and animal material that improves soil health
Soil erosion – The loss of topsoil due to wind and water
Carbon release – The amount of carbon dioxide (CO2) released from soil into the atmosphere
Climate change effects (drought, heavy rain) – Weather patterns influenced by global warming
Land expansion for farming – The conversion of forests or grasslands into cropland
Relationships between the parts
Increased fertiliser and pesticide use → decreases organic matter in soil
Decreased organic matter in soil → reduces soil fertility
Reduced soil fertility → decreases crop yields
Lower crop yields → increases fertilizer and pesticide use (reinforcing loop)
Increased tillage → leads to more soil erosion
More soil erosion → reduces soil fertility
Reduced soil fertility → increases land expansion for farming
Land expansion (deforestation) → increases carbon release
Increased carbon release → worsens climate change effects
More climate change effects (drought, heavy rain) → increases soil erosion (reinforcing loop)
Checking for understanding
Checking for understanding
Further exploration
Further exploration
How Wolves Change Rivers – A short video narrated by George Monbiot explaining how the reintroduction of wolves to Yellowstone Park altered the ecosystem and even changed the course of rivers. Difficulty level: easy.
Daisyworld – NASA’s animated explanation of James Lovelock’s GAIA concept, illustrating how planetary systems self-regulate through feedback loops. Difficulty level: easy.
Global Tipping Points Report 2023 - An authoritative assessment of the risks and opportunities of both negative and positive tipping points in the Earth system and society. Difficulty level: medium
Exceeding Earth's Safe Limits with Johan Rockström – In this interview, Professor Johan Rockström discusses the planetary boundaries framework, highlighting how human activities are pushing Earth's systems beyond safe operating limits. Difficulty level: medium.
Loopy - An intuitive tool for creating interactive causal loop diagrams. Ideal for beginners to explore feedback loops and system behavior. Difficulty level: easy.
Insight maker - A web-based tool for system dynamics and agent-based modeling. Supports causal loop diagrams and simulations for in-depth analysis. Difficulty level: medium.
System dynamics underlying car dependency - This short OECD video explains the reinforcing and balancing feedback loops associated with cars and road building. Is building more and wider roads the solution for traffic congestion? Note: the red arrows indicate direct + relationships in the video diagrams and the blue arrows indicate indirect - relationships. Difficulty level: medium.
Tools of Systems Thinking Courses - short courses (1-hour each) explaining some key tools of systems thinking, from the Waters Center for Systems Thinking. Relevant courses for Section S.3 include (Difficulty level: medium):
Tools Course #5: Causal Links
Tools Course #6: Causal Connection Circle Mapping
Tools Course #7: Causal Loop Diagrams Part 1: Reinforcing Feedback
Tools Course #8: Causal Loop Diagrams Part 2: Balancing Feedback
Tools Course #9: Causal Loop Diagrams Part 3: Bringing Reinforcing and Balancing Loops Together
The Systems Thinking Playbook – A practical guide by Linda Booth Sweeney and Dennis Meadows, offering hands-on exercises to develop systems thinking skills through understanding feedback loops, delays, and interconnected systems in an engaging way. It is widely used in education, leadership training, and sustainability studies. Difficulty level: medium.
Sources
Sources
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ). (2011). Playbook for climate action: A practitioners’ guide to climate change communication and engagement. The Systems Thinking Playbook for Climate Change
Cabrera, D., & Cabrera, L. (2018). Systems thinking made simple: New hope for solving wicked problems (2nd ed.). Odyssean Press.
The Guardian. (2024, February 13). Flourishing vegetation on Greenland ice sheet raises alarm over climate crisis. https://www.theguardian.com/world/2024/feb/13/flourishing-vegetation-greenland-ice-sheet-alarm-climate-crisis
Meadows, D. H. (2008). Thinking in systems: A primer. White River Junction, VT: Chelsea Green Publishing.
Terminology (in order of appearance)
Terminology (in order of appearance)
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