Embedded Files
How can the systems approach be used to model environmental issues at different levels of complexity and scale?
What is a system?
What is a system?
1.2.1 Systems are sets of interacting or interdependent components.
System components are organized to create a functional whole.
1.2.7 The concept of a system can be applied at a range of scales.
A school
A school
The students, teachers, computers, pens etc. are components.
The teachers teach the students.
The computers allow email comms.
Halcyon School is a single whole 'thing'.
1.2.2 A systems approach is a holistic way of visualizing a complex set of interactions, and it can be applied to ecological or societal situations.
In the Solomon Islands, there are several different water sources, and several different threats to each of them.
Using a system approach helps visualise all the complex interactions in this social situation.
In Costa Rica, there is a desire to connect conservation goals with social and economic development .
Using a system approach helps visualise all the complex interactions in this social and ecological situation.
What is the benefit of representing the ecological relationships in Hyde Park like this?
How do we visually represent systems?
How do we visually represent systems?
A system has storages and flows, with flows providing inputs and outputs of energy and matter.
1.2.3 In system diagrams, storages are usually represented as rectangular boxes and flows as arrows, with the direction of each arrow indicating the direction of each flow.
Draw systems diagrams for:
A bath
A population of rats
An oak tree
1.2.4 Flows are processes that may be either transfers or transformations.
Transfers involve a change in location of energy or matter
Tansformations involve a change in the chemical nature, a change in state or a change in energy.
Re-open your activities document. Move each flow to either the transfers or transformations side.
1.2.5 Systems can be open or closed.
An open system exchanges both energy and matter across its boundary, while a closed system exchanges only energy across its boundary. almost all systems are open; only the global geochemical cycles approximate to closed systems.
Biosphere 2 is an example of a closed system, and a local ecosystem is an example of an open system.
We will make some open and closed bottle ecosystems.
The system is closed if we seal it - light and heat energy can get in and out, but no matter gets in or out.
The system is open if we leave it... Well... Open. Air, water, bacteria etc. can get in and out as well as the energy.
Earth is a system
Earth is a system
1.2.6 The Earth is a single integrated system encompassing the biosphere, the hydrosphere, the cryosphere, the geosphere, the atmosphere and the anthroposphere.
Re-open your activities document. Annotate the diagram shown below
James Lovelock’s Gaia hypothesis is a model of the Earth as a single integrated system. The hypothesis (also known as the Gaia theory) was introduced to explain how atmospheric composition and temperatures are interrelated through feedback control mechanisms. Many variations of the Gaia theory were further developed by James Lovelock and Lynn Margulis.
Re-open your activities document. Work in pairs to complete the table shown above.
1.2.15 Interactions between components in systems can generate emergent properties.
"There's no love in a carbon atom, No hurricane in a water molecule, No financial collapse in a dollar bill."
– Peter Dodds
An emergent property is a feature that the whole system has that the components don't.
A whole person can be alive, their ear alone can't. Life is an emergent property of living systems.
A whole farm can feed a family, the soil alone can't.
A whole rainforest can generate enough cloud to keep it raining, an individual tree can't.
We do: A whole plane can _______, the ________ alone can't. _______ is an emergent property of a plane.
You do: A whole ___________________ , _____________________ can't
Feedback Loops, Equilibria and Tipping Points
Feedback Loops, Equilibria and Tipping Points
1.2.8 Negative feedback loops occur when the output of a process inhibits or reverses the operation of the same process in such a way as to reduce change. They are stabilizing as they counteract deviation.
Think, Pair, Share: explain the Daisyworld model in only 3 words
1.2.10 Positive feedback loops occur when a disturbance leads to an amplification of that disturbance, destabilizing the system and driving it away from its equilibrium.
Positive feedback loops have amplifying roles. Positive feedback can lead to both an increase or a decrease in a system component.
For example, as a population declines, the reproductive potential decreases leading to further decrease.
Other examples of positive feedback are the reduced albedo (amount of reflection by a surface) due to melting ice caps leading to greater global warming, or an increase in population leading to increased potential for further growth. There are many other examples.
POSITIVE FEEDBACK LOOPS
Often bad
Amplify changes
Destabilise systems
Lead to tipping points
NEGATIVE FEEDBACK LOOPS
Often good
Minimise changes
Stabilise systems
Try to copy the summary above into your notes from memory.
Working in pairs, copy and complete the document below.
Use ChatGPT to find more examples of positive and negative feedbacks in environmental systems.
Use StoryboardThat to create a comic strip about your feedback loop.
Show it to your classmates and see if they can correctly describe the loop.
1.2.9 As an open system, an ecosystem will normally exist in a stable equilibrium, either in a steady-state equilibrium or in one developing over time (for example, succession), and will be maintained by stabilizing negative feedback loops.
A stable equilibrium is the condition of a system in which there is a tendency for it to return to the previous equilibrium following disturbance. A steady-state equilibrium is the condition of an open system in which flows are still occurring but inputs are constantly balanced with outputs.
In pairs, classify these examples
Your body temperature is 37.0°C. Someone puts the heating on. You warm up to 37.1°C. You sweat and cool down to 37.0°C.
A hare population increases. This causes a larger population of lynx, who eat hares. This causes the hare population to decrease. This reduces lynx numbers, allowing the hare population to increase.
A pH buffer maintains the pH of a test tube of water at a constant pH of 4.2 for 10 weeks.
This equilibrium is in a steady state.
This equilibrium (it's an equilibrium because it fluctuates up and down) is developing over time.
We'll learn more about succession later in the course.
Credit to InThinking for the above
1.2.11 Positive feedback loops will tend to drive the system towards a tipping point.
1.2.12 Tipping points can exist within a system where a small alteration in one component can produce large overall changes, resulting in a shift in equilibrium.
A tipping point is the minimum amount of change that will cause destabilization within a system. The system then shifts to a new equilibrium or "alternative stable state".
Models
Models
1.2.13 A model is a simplified representation of reality; it can be used to understand how a system works and to predict how it will respond to change.
1.2.14 Simplification of a model involves approximation and, therefore, loss of accuracy.
1.2.16 The resilience of a system, ecological or social, refers to its tendency to avoid tipping points and maintain stability.
Resilience of a system is the capacity to resist damage and recover from, or adapt efficiently to, disturbance.
1.2.17 Diversity and the size of storages within systems can contribute to their resilience and affect their speed of response to change (time lags).
Compare the pairs of images.
Discuss in pairs: which is the most resilient, and why?
1.2.18 Humans can affect the resilience of systems through reducing these storages and diversity.
Tipping Points Case Study
Ecologists have developed a database of demonstrated tipping points. Find that here:
Your task is to add an example to the Google Map below.
https://drive.google.com/open?id=1525ZbztkVnic2BHYsfoj2gB8sQrGVPmZ&usp=sharing
You should discuss
What sources of resilience the example had (think about diversity, size of storages and negative feedback)
What sources of resilience the example lacked (think about diversity, size of storages and negative feedback).
How humans reduced storages and diversity (which contribute to resilience).
What tipping point was reached.
What complexities make the outcome hard to model in this case.
You are going to spend the next two years hearing this over and over again!
Further Reading
Introduction-to-Systems-Thinking-IMS013Epk.pdfLeverage_Points.pdfPage updated
Report abuse