topic 1.2: systems
A system is an assemblage of parts, working together, forming a functional whole. Many types of environmental systems exist. From cells, to people, to cars, to economies to the whole planet. Systems occur on different scales.
The systems approach is central to the course and has been employed for a number of reasons. The very nature of environmental issues demands a holistic treatment. In reality, an environmental system functions as a whole and the traditional reductionist approach of science inevitably tends to overlook or, at least, understate this important quality. Furthermore, the systems approach is common to many disciplines (for example, economics, geography, politics, ecology). It emphasizes the similarities between the ways in which matter, energy and information flow (not only in biological systems but in, for example, transport and communication systems). This approach therefore integrates the perspectives of different disciplines.
In this unit you will be introduced to the characteristics of environmental systems. Identifying some of the underlying principles that can be applied to living systems, from the level of the individual up to that of the whole biosphere.
This unit will take a minimum of 5 hours.
The systems approach is central to the course and has been employed for a number of reasons. The very nature of environmental issues demands a holistic treatment. In reality, an environmental system functions as a whole and the traditional reductionist approach of science inevitably tends to overlook or, at least, understate this important quality. Furthermore, the systems approach is common to many disciplines (for example, economics, geography, politics, ecology). It emphasizes the similarities between the ways in which matter, energy and information flow (not only in biological systems but in, for example, transport and communication systems). This approach therefore integrates the perspectives of different disciplines.
In this unit you will be introduced to the characteristics of environmental systems. Identifying some of the underlying principles that can be applied to living systems, from the level of the individual up to that of the whole biosphere.
This unit will take a minimum of 5 hours.
Guiding Question:
- How can the systems approach be used to model environmental issues at different levels of complexity and scale?
systems
1.2.1 Systems are sets of interacting or interdependent components.
- Define systems
- Explain the component parts and the emergent properties of a system.
- Outline the concept and characteristics of systems.
- Outline the Gaia Hypothesis
- Using an example, describe the concept of systems diagrams. Include the descriptors of flows, storages, transfers, transformations, and feedback loops.
image from sciencebitz.com
SYSTEM: an assemblage of parts and their relationship forming a functioning entirety or whole. There are two major components to a system:
During the 1970’s, British chemist James Lovelock and American biologist Lynn Margulis came up with the GAIA HYPOTHESIS: That the world acts like a single biological being made up of many individual and interconnected units (A SYSTEM ).
- Elements - measurable things that can be linked together. Example, trees, shrubs, herbs, birds and insects (items we can count, measure or weight
- Processes - change elements from on form to another. These may also be called activities, relations, or functions. Example, growth, mortality, decomposition, and disturbances (what happens to the elements, or what the elements do)
During the 1970’s, British chemist James Lovelock and American biologist Lynn Margulis came up with the GAIA HYPOTHESIS: That the world acts like a single biological being made up of many individual and interconnected units (A SYSTEM ).
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.
- Systems Approach:
- A holistic method to understand complex interactions in ecological and societal contexts by visualizing interconnected components.
- Key Components:
- Storages: Reservoirs where energy or matter is held.
- Flows: Movement of energy or matter between storages, acting as inputs and outputs.
- Applications:
- Ecological Systems: Models nutrient cycles like carbon and nitrogen, showing how changes in one part can impact the entire ecosystem.
- Societal Systems: Analyzes human systems (e.g., cities) to identify inefficiencies and environmental impacts, guiding sustainable practices.
- Benefits of the Systems Approach:
- Holistic Understanding: Provides a complete view, including direct and indirect effects of changes within the system.
- Informed Decision-Making: Supports decisions that consider long-term impacts and interdependencies.
- Emergent Properties:
- Systems produce unique outcomes that their individual parts couldn’t create alone. For example, two forests may have the same trees but create different wildlife habitats due to tree arrangement and size—an emergent property.
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.
- Describe the structure of a system
- Distinguish between flows (inputs and outputs) and storages (stock) in relation to systems
- List two examples of storage
- List two examples of flows
System diagrams are vital tools in environmental science for visualizing and understanding the complex interactions within ecological and societal systems. These diagrams help clarify how components of a system are organized and interact over time. In system diagrams:
Function and Utility
Using system diagrams allows students and researchers to visually map out and analyze the various elements and dynamics of a system. By representing storages and flows clearly:
Applications
Application of skills: Create systems diagrams representing the storages and flows, inputs and outputs of systems, such as a lab-based or local natural ecosystems. The size of the boxes and the arrows may be representative of the size/magnitude of the storage or flow.
- Inputs - import energy and matter across the system boundary
- Output - export energy and matter across the system boundary
- Storages: These are typically represented as rectangular boxes. Storages in a system diagram signify where energy or matter is held within the system, such as a lake for water, a forest for carbon, or a city for population.
- Flows: Flows are depicted as arrows, with each arrow indicating the direction of the flow of energy or matter between storages. This representation helps trace the movement of resources through the system, showing how they enter, move through, and exit the system.
Function and Utility
Using system diagrams allows students and researchers to visually map out and analyze the various elements and dynamics of a system. By representing storages and flows clearly:
- Directionality: The arrows not only show where resources are moving but also give insight into the processes influencing these movements, such as evaporation, consumption, migration, or technological transfer.
- Interconnections: Understanding how different storages are connected helps in predicting how changes in one part of the system might impact other parts, crucial for effective environmental management and decision-making.
Applications
- Ecological Analysis: In ecological studies, system diagrams can illustrate nutrient cycles, energy flow in food webs, or the movement of pollutants in an ecosystem.
- Societal and Economic Systems: These diagrams are also useful in depicting the flow of money, goods, and services within an economy or the distribution of resources like water and electricity in urban planning.
Application of skills: Create systems diagrams representing the storages and flows, inputs and outputs of systems, such as a lab-based or local natural ecosystems. The size of the boxes and the arrows may be representative of the size/magnitude of the storage or flow.
image from yesitsyomoma.wordpress.com
System diagrams consist of:
Diagram can be labelled with the processes on each arrow:
The size of the boxes and arrows in the systems diagram an be drawn to represent the magnitude of the storage or flow.
- boxes show storages
- arrows show flows (inputs/outputs)
Diagram can be labelled with the processes on each arrow:
- Photosynthesis – transformation of CO2, H2o and light into biomass and oxygen O2
- Respiration – transformation of biomass into CO2 and water
- Diffusion – movement of nutrients and water
- Consumption – tissue transfer from trophic level to another
The size of the boxes and arrows in the systems diagram an be drawn to represent the magnitude of the storage or flow.
Case Study: The Amazon Rainforest Carbon Cycle
Overview of the Amazon Rainforest
The Amazon Rainforest, often referred to as the "lungs of the Earth," is a vast tropical rainforest covering much of the Amazon Basin in South America. This rainforest is crucial for global carbon cycling, acting as a significant carbon sink that absorbs and stores large amounts of carbon dioxide from the atmosphere.
Components of the Amazon Carbon Cycle
Flows in the Carbon Cycle
Importance of the Amazon Carbon Cycle
Understanding the carbon cycle of the Amazon Rainforest is vital for several reasons:
Overview of the Amazon Rainforest
The Amazon Rainforest, often referred to as the "lungs of the Earth," is a vast tropical rainforest covering much of the Amazon Basin in South America. This rainforest is crucial for global carbon cycling, acting as a significant carbon sink that absorbs and stores large amounts of carbon dioxide from the atmosphere.
Components of the Amazon Carbon Cycle
- Vegetation: The dense forests of the Amazon, comprising millions of trees and other plant species, play a key role in the carbon cycle. Through the process of photosynthesis, plants absorb CO2, using carbon to grow and releasing oxygen back into the atmosphere.
- Soil: Amazonian soils are another critical component, storing carbon in the form of organic matter. Decomposition processes further break down this matter, releasing carbon slowly over time.
- Atmosphere: The atmosphere interacts with the forest, supplying CO2 for photosynthesis and receiving oxygen in return. The balance of these gases is crucial for climate regulation.
Flows in the Carbon Cycle
- Photosynthesis: Plants absorb carbon dioxide from the atmosphere and convert it into organic matter, releasing oxygen as a byproduct.
- Respiration: Both plants and animals respire, releasing CO2 back into the atmosphere.
- Decomposition: When plants and animals die, decomposers like fungi and bacteria break down the organic material, releasing stored carbon back into the atmosphere as CO2.
- Riverine Transport: Some of the carbon in the Amazon is transported by rivers as dissolved carbon or in the form of dead organic matter. This carbon can be deposited as sediment or reach the ocean.
- Deforestation and Disturbances: Human activities such as logging and land conversion for agriculture release significant amounts of CO2 by reducing the forest's capacity to store carbon. Forest fires, often a result of human actions or natural events, also release stored carbon quickly.
Importance of the Amazon Carbon Cycle
Understanding the carbon cycle of the Amazon Rainforest is vital for several reasons:
- Climate Regulation: The Amazon's ability to store and cycle carbon is a critical factor in global climate regulation, influencing global warming and climate change.
- Biodiversity: The cycle supports the rainforest’s vast biodiversity, which depends on the forest's health and stability.
- Human Impact: It highlights the impact of human activities on a major natural carbon sink, underscoring the need for sustainable forest management and conservation strategies to mitigate climate change.
1.2.4 Flows are processes that may be either transfers or transformations.
- Describe the flow of energy and matter into and out of a system
- Explain the differences between energy flows and matter cycles.
- Define inputs, outputs and stock
- List two examples of inputs
- List two examples of outputs
In environmental systems and societies, flows within system diagrams represent the dynamic processes through which energy or matter moves from one storage to another. These flows are crucial for understanding how systems operate and are classified into two main types, transfers and transformations
Transfers:
Transformations:
Transfers include
Transformations include
- The movement of material through living organisms
- Movement of material in non-living process
- The movement of energy
Transformations:
- Matter to matter
- Energy to energy
- Matter to energy
- Energy to matter
Transfers include
- harvesting of forest products
- fall of forest debris on the ground
Transformations include
- photosynthesis
- respiration
Importance of Understanding Flows
Understanding whether a flow is a transfer or a transformation is essential for accurately analyzing system dynamics. Each type of flow has different implications for how energy and matter are conserved and distributed within a system, affecting everything from ecosystem health to resource management strategies.
Understanding whether a flow is a transfer or a transformation is essential for accurately analyzing system dynamics. Each type of flow has different implications for how energy and matter are conserved and distributed within a system, affecting everything from ecosystem health to resource management strategies.
- System Stability and Efficiency:
- Identifying flows helps predict system-wide impacts, such as how increased river discharge affects downstream ecosystems and water availability.
- Management and Intervention:
- Understanding flows allows for better environmental management by enhancing beneficial flows or mitigating harmful ones. For example, knowing that nitrogen fixation is a transformation aids in managing soil fertility in agriculture.
1.2.5 Systems can be open or closed.
- Define and use the term open system. Use examples of real systems to characterize an open system
- Define and use the term closed system. Use examples of real systems to characterize an closed system.
- Describe closed, open, and isolated systems in terms of matter and energy exchange
- Draw systems diagrams of an open, closed, and isolated system
- Using the terms open, closed, and/or isolated system describe a population of elephants living on an African grassland.
An open system is a system that regularly exchanges feedback with its external environment. Open systems are systems, of course, so inputs, processes, outputs, goals, assessment and evaluation, and learning are all important. Aspects that are critically important to open systems include the boundaries, external environment and equifinality.
Healthy open systems continuously exchange feedback with their environments, analyze that feedback, adjust internal systems as needed to achieve the system’s goals, and then transmit necessary information back out to the environment.
Examples of an open system
Healthy open systems continuously exchange feedback with their environments, analyze that feedback, adjust internal systems as needed to achieve the system’s goals, and then transmit necessary information back out to the environment.
Examples of an open system
- A Forest Ecosystem
- A lake
A closed system in which there is no transfer of mass takes place across the boundaries of system but energy transfer is possible. Other than the universe itself, an isolated system does not exist in practice. However, a very well insulated and bounded system with negligible loss of heat is roughly an isolated system, especially when considered within a very short amount of time.
Examples of a closed system
Examples of a closed system
- The earth is a closed system.
- Biosphere 2
- Water cycle
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1.2.6 The Earth is a single integrated system encompassing the biosphere, the hydrosphere, the cryosphere, the geosphere, the atmosphere and the anthroposphere.
- Define the Gaia hypothesis\
- Explain how the Gaia views the Earth compared to traditional environmental science perspectives.
- Discuss the role of the biosphere in maintaining Earth's stability according to the Gaia hypothesis.
- Explain how human activities (anthroposphere) have affected the Earth's self-regulating mechanisms as proposed by the Gaia hypothesis
https://mynasadata.larc.nasa.gov/sites/default/files/2018-09/Spheres%20Circle-02_small_0.png
The Earth is not merely a collection of isolated components but a complex, integrated system made up of several interconnected spheres. These include the biosphere (all living organisms and their interactions), the hydrosphere (all of the Earth's water bodies), the cryosphere (areas covered by ice and snow), the geosphere (the Earth's solid rocks and minerals), the atmosphere (the layer of gases surrounding Earth), and the anthroposphere (human activities and their impacts). The interactions among these spheres create a dynamic system that sustains life and shapes natural processes on our planet.
https://aeon.co/essays/gaia-why-some-scientists-think-its-a-nonsensical-fantasy
James Lovelock’s Gaia Hypothesis
- The Gaia Hypothesis, developed by James Lovelock and Lynn Margulis, views Earth as a single, self-regulating system, like a living organism.
- Key Idea: The biosphere interacts with inorganic surroundings through feedback mechanisms that help maintain environmental balance, creating conditions favorable for life.
- Feedback Control Mechanisms:
- A core element of the Gaia hypothesis, these mechanisms help keep Earth's conditions (like climate and ocean salinity) stable and within life-sustaining limits.
- Example: The biosphere regulates atmospheric oxygen through photosynthesis and respiration, while biological and geological processes manage greenhouse gases to control Earth’s temperature.
- Development of Gaia Theory:
- The Gaia theory has evolved to explore both stabilizing and destabilizing effects of biological processes on Earth’s climate, contributing to discussions on climate change and sustainability.
https://www.mathworks.com/matlabcentral/fileexchange/113635-daisyworld-with-greenhouse-effect
Daisyworld
Daisyworld is a hypothetical model created by James Lovelock and Andrew Watson as a simple simulation to explore the Gaia hypothesis. The model demonstrates how life can regulate climate through feedback loops. Daisyworld imagines a planet orbiting a star, where the surface is populated solely by white and black daisies, alongside inorganic, barren land
Daisyworld is a hypothetical model created by James Lovelock and Andrew Watson as a simple simulation to explore the Gaia hypothesis. The model demonstrates how life can regulate climate through feedback loops. Daisyworld imagines a planet orbiting a star, where the surface is populated solely by white and black daisies, alongside inorganic, barren land
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1.2.7 The concept of a system can be applied at a range of scales.
- Explain, using examples, that systems can vary in size.`
The concept of a system is versatile and can be applied across a multitude of scales, from the minutely small to the expansively large. This flexibility allows us to analyze and understand different types of environments and interactions within them, whether they occur in a tiny ecosystem or on a global scale.
Examples of Systems at Different Scales:
Small-Scale Systems:
Examples of Systems at Different Scales:
Small-Scale Systems:
- Example: A Bromeliad in a Rainforest
- Description: On a small scale, a bromeliad hosting its own mini-ecosystem provides a clear example of a system. This plant collects water in its leaves, creating a habitat for various organisms such as insects, frogs, and microorganisms. In this micro-ecosystem, the bromeliad acts as a storage for nutrients and water, while the organisms represent different components interacting within this system. The processes include nutrient cycling and energy flows between the organisms and the plant.
- Example: A Rainforest
- Description: At a larger scale, a rainforest encompasses a vast array of life forms and abiotic components interacting in a complex system. It includes various sub-systems like individual forest patches, rivers, and wildlife populations. The rainforest system regulates climate, recycles carbon and water, and supports immense biodiversity, demonstrating interconnected processes and feedback mechanisms.
- Example: Atmospheric Circulation
- Description: On a global scale, global atmospheric circulation, which includes wind patterns that distribute heat and moisture around the planet, exemplifies a system that operates on a planetary level. These global systems show how local and regional processes scale up to affect and regulate the entire planet.
- It helps us recognize how local actions can have far-reaching effects.
- It allows for the identification of patterns and feedback loops that operate at various levels.
- It provides insight into how changes in one part of a system can impact the system at a larger scale.
feedback loops
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.
- Describe and draw systems diagrams of two examples of negative feedback
- Application of skills: Use diagrams representing examples of negative feedback.
Negative Feedback Loops:
- These loops stabilize systems by counteracting deviations from a set state. When the output of a process reduces the effect of that process, change is minimized, helping maintain system stability.
https://www.mathworks.com/matlabcentral/fileexchange/113635-daisyworld-with-greenhouse-effect
Daisyworld Model: An Illustration of Negative Feedback
Mechanism: On this hypothetical planet, black and white daisies regulate temperature. When the planet warms, white daisies (which reflect sunlight) grow more, cooling the surface. When it cools, black daisies (which absorb heat) become dominant, warming the planet. This dynamic helps maintain a stable temperature conducive to life.
- Created by James Lovelock and Andrew Watson, Daisyworld illustrates negative feedback in an environmental context.
Mechanism: On this hypothetical planet, black and white daisies regulate temperature. When the planet warms, white daisies (which reflect sunlight) grow more, cooling the surface. When it cools, black daisies (which absorb heat) become dominant, warming the planet. This dynamic helps maintain a stable temperature conducive to life.
Other Examples of Negative Feedback Loops:
https://energyeducation.ca/encyclopedia/Negative_feedback
Climate Regulation by Carbon Dioxide:
- In natural ecosystems, increased levels of carbon dioxide can lead to more plant growth (assuming other nutrients are sufficient), which in turn increases the rate of photosynthesis. This process removes carbon dioxide from the atmosphere, moderating global temperatures and demonstrating a negative feedback effect.
Human Body Temperature Regulation:
- In humans, when body temperature rises above the normal range, mechanisms such as sweating are triggered to cool the body down, thereby returning the temperature to a normal range. Conversely, if the temperature falls, shivering generates heat to raise the body temperature.
https://www.mylearning.org/stories/ecological-interactions/1511
Predator-Prey Dynamics:
- In ecological systems, an increase in prey population often leads to an increase in predators. However, as the predator population grows, the prey population begins to decrease due to higher predation, which eventually reduces the predator population, maintaining balance in the ecosystem.
Economic Market Corrections:
- In economics, negative feedback can be observed in market corrections where an overheated economy may lead to increased interest rates, slowing down spending and investment, thus stabilizing economic growth and preventing inflation.
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.
- Explain the stable and steady-state equilibrium
- Using examples, explain how complexity of a system can lead to its stability.
- Explain the nature of equilibrium
- Describe what is meant by steady-state equilibrium and explain how it is stabilized by negative feedback.
- Explain how negative feedback loops stabilize an ecosystem to produce steady state equilibrium.
- Discuss how negative feedback loops maintain equilibrium
Ecosystems constantly exchange energy and matter with their surroundings, maintaining conditions that support life and often reaching an equilibrium.
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Types of Equilibrium:
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 www.nature.com
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Ecosystem Development and Succession:
Ecosystems can also evolve from one equilibrium state to another through ecological succession, a process where the species composition and community structure of an ecosystem change over time, usually following a disturbance. Succession itself is a form of development toward a new equilibrium.
Ecosystems can also evolve from one equilibrium state to another through ecological succession, a process where the species composition and community structure of an ecosystem change over time, usually following a disturbance. Succession itself is a form of development toward a new equilibrium.
- Example: After a glacier retreats, the exposed ground goes through stages of succession starting from lichens and mosses, progressing to grasses and shrubs, and eventually developing into a mature forest. Each stage creates conditions conducive to the next, slowly moving the ecosystem toward a new stable equilibrium.
https://www.sciencedirect.com/science/article/abs/pii/S0048969723022490
Role of Negative Feedback Loops:
Negative feedback loops are crucial in maintaining equilibrium within ecosystems. They function by reducing the effects of disturbances, thus stabilizing the ecosystem. For instance, if a sudden increase in a particular herbivore population begins to deplete vegetation excessively, this could lead to starvation and a subsequent decrease in the herbivore population, allowing vegetation levels to recover.
Negative feedback loops are crucial in maintaining equilibrium within ecosystems. They function by reducing the effects of disturbances, thus stabilizing the ecosystem. For instance, if a sudden increase in a particular herbivore population begins to deplete vegetation excessively, this could lead to starvation and a subsequent decrease in the herbivore population, allowing vegetation levels to recover.
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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.
- Compare and contrast positive and negative feedback loops.
- Describe and draw systems diagrams of two examples of positive feedback.
https://mrsbsciencecorner.wordpress.com/2018/08/13/feedback-loops/
- Positive Feedback (Destabilizing):
- Positive feedback amplifies changes, pushing the system out of equilibrium and into a new state.
- It drives rapid, compounding changes by increasing one part of the system in response to changes in another, creating instability.
- Examples:
- Population Growth: An increase in population leads to more births, which further increases the population.
- Melting Ice Caps: Reduced albedo from melting ice increases global warming, which leads to more ice melt, further destabilizing the climate.
Application of skills: Use diagrams representing examples of positive feedback.
A causal loop diagram is a type of system diagram that shows the complex relationships between different variables in a system. A causal loop diagram has four basic elements:
- the variables
- the causal connections between the variables (which variable influences the other)
- the type of influence, a direct relationship (indicated by + symbol) or inverse relationship (indicated by - symbol)
- the type of loop, indicating either negative (balancing) or positive (reinforcing) feedback loops, if such behaviour is present. Negative (balancing) feedback is indicated with a B, and positive (reinforcing feedback) is indicated with an R
https://www.sciencedirect.com/science/article/pii/S0377221716304362
1.2.11 Positive feedback loops will tend to drive the system towards a tipping point.
- Describe the concept of a tipping point in an ecosystem.
- Explain how Arctic ice melt represents a positive feedback loop
- Positive Feedback Loops:
- These loops amplify the effects of changes, accelerating movement toward extremes or new states, unlike negative feedback that stabilizes systems.
- Tipping Points:
- A tipping point is a critical threshold where a small change triggers significant, often irreversible shifts in an ecosystem, leading to a new equilibrium.
- Examples:
- Arctic Ice Melt: Warming leads to ice melt, reducing albedo and further accelerating warming, potentially leading to ice-free Arctic summers.
- Deforestation and Carbon Levels: Reduced forests mean less CO₂ absorption, raising atmospheric carbon, increasing temperatures, and further harming forests, possibly transforming them into savannas.
- Implications:
- Recognizing positive feedback loops and tipping points helps predict and mitigate irreversible environmental changes, such as through emission reductions or reforestation efforts.
tipping points
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.
- Outline how a tipping point differs from gradual change in an ecosystem.
- Discuss how tipping points can impact the stability of environmental systems
Tipping points in environmental systems are critical thresholds where small changes in one component can lead to significant, often abrupt changes across the entire system. These changes can result in regime shifts, where the system transitions between alternative stable states. Such shifts usually have profound implications, altering the structure and function of ecosystems dramatically and often irreversibly.
Mechanics of Tipping Points and Regime Shifts
Tipping points arise when incremental alterations accumulate to trigger feedback mechanisms that push a system beyond its capacity to maintain its current state. This can lead to a regime shift—a fundamental change in the system's equilibrium. Understanding these dynamics is crucial for predicting and managing environmental changes effectively.
Examples of Tipping Points and Regime Shifts:
Eutrophication from Nutrient Loading:
Coral Reef Bleaching:
Forest to Savanna Transition:
Implications of Understanding Tipping Points
Identifying potential tipping points is essential for environmental management, allowing for interventions that can prevent undesirable regime shifts. By understanding these critical thresholds, scientists and policymakers can implement strategies to maintain ecosystem stability and prevent irreversible damages.
Systems at threat from tipping points include:
Mechanics of Tipping Points and Regime Shifts
Tipping points arise when incremental alterations accumulate to trigger feedback mechanisms that push a system beyond its capacity to maintain its current state. This can lead to a regime shift—a fundamental change in the system's equilibrium. Understanding these dynamics is crucial for predicting and managing environmental changes effectively.
Examples of Tipping Points and Regime Shifts:
Eutrophication from Nutrient Loading:
- An increase in nutrients, such as nitrates and phosphates (often from agricultural runoff or sewage discharge), can lead to eutrophication in aquatic systems. This process enriches the water, leading to excessive growth of algae and depletion of oxygen. As oxygen levels decrease, the water can no longer support the same aquatic life, leading to a shift from clear, oxygen-rich waters to turbid, oxygen-poor conditions—a new regime that significantly alters the aquatic ecosystem.
Coral Reef Bleaching:
- Coral reefs can experience a regime shift when sustained high water temperatures lead to widespread bleaching. The loss of symbiotic algae makes the corals white and weakens them, reducing their capacity to sustain marine life. If the stress continues, this can lead to a permanent shift from vibrant coral ecosystems to barren underwater landscapes, drastically reducing biodiversity and altering marine habitats.
Forest to Savanna Transition:
- In tropical regions, slight changes in climate and human activities like deforestation can reduce rainfall and disrupt the water cycle enough to shift the ecosystem from dense forest to savanna. This regime shift involves significant changes in species composition, biodiversity, and carbon storage capabilities.
- Overfishing can lead fisheries to a tipping point where the fish population cannot sustain itself due to insufficient reproduction rates. This results in a regime shift from a thriving fish population to one that is economically and ecologically unsustainable, impacting species survival and community livelihoods.
Implications of Understanding Tipping Points
Identifying potential tipping points is essential for environmental management, allowing for interventions that can prevent undesirable regime shifts. By understanding these critical thresholds, scientists and policymakers can implement strategies to maintain ecosystem stability and prevent irreversible damages.
Systems at threat from tipping points include:
- Antarctic sea ecosystems
- Arctic sea-ice
- Greenland ice sheet
- West Antarctic ice sheet
- El-Niño-Southern Oscillation (ENSO)
- West African monsoon
- Amazon rainforest
- boreal forest.
- thermohaline circulation (THC)
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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.
- Explain, using examples, what models are.
- Apply the systems concept on a range of scales.
image from www.eaps.purdue.edu
A model is a simplified description designed to show the structure or workings of an object, system or concept. In practice, some models require approximation techniques to be used. For example, predictive models of climate change may give very different results. In contrast, an aquarium may be a relatively simple ecosystem but demonstrates many ecological concepts.
Models summarize complex systems. Therefore they can lead to loss of information and oversimplification. A model involves some approximation and therefore losses accuracy.
Models summarize complex systems. Therefore they can lead to loss of information and oversimplification. A model involves some approximation and therefore losses accuracy.
image from https://earth.esa.int/web/guest/sciamachy-handbook-version-2;jsessionid=C1073669E91C3E35D034E935DECF14A1.jvm2?p_p_id=36&p_p_lifecycle=0&p_p_state=pop_up&p_p_mode=view&controlPanelCategory=portlet_36&_36_struts_action=%2Fwiki%2Fview&_36_nodeName=SCIAMACHY+Handbook+2.0&_36_title=Anthropogenic+Impact+on+the+Earth-Atmosphere+System
1.2.14 Simplification of a model involves approximation and, therefore, loss of accuracy.
- Evaluate the strengths and limitations of systems models.
In the study of environmental systems, models are essential tools used to understand and predict complex interactions within ecosystems and global processes. However, creating these models often requires simplification, which involves reducing the complexity of the real world into more manageable parts. While simplification makes models easier to work with and understand, it inherently involves approximation and, consequently, a loss of accuracy.
Strengths:
Strengths:
- allow scientist to predict/simplify complex systems
- inputs can be changed and outcomes examined without having to wait for real events.
- results can be shown to scientists and the public
- might not be totally accurate
- environmental factors are very complex
- different models use slightly different data to calculate predictions
- rely on the expertise of people making them
- different people may interpret them in different ways
- vested interests might hijack them politically
- any model is only as good as the data goes in and these may be suspect
- different models may show different effects using the same data
1.2.15 Interactions between components in systems can generate emergent properties.
- Describe the emergent properties
A holistic approach is necessary to fully understand the way in which the parts of a complex system operates togher. An emergent property is a property which a collection or complex system has, but which the individual members do not have. A failure to realize that a property is emergent, or supervenient, leads to the fallacy of division.
resilence
1.2.16 The resilience of a system, ecological or social, refers to its tendency to avoid tipping points and maintain stability.
- Explain what is meant by resilience of a system
- Explain how resilience avoids tipping points.
- Discuss natural and human factors that affect resilience in systems.
www.oceanclimatechange.org.au
Resilience in both ecological and social systems refers to the capacity of these systems to resist, recover from, and adapt to disturbances or changes. This characteristic is crucial for maintaining the system's stability and avoiding tipping points—critical thresholds beyond which a system undergoes irreversible changes.
Components of Resilience
Importance of Resilience
Resilience is essential for the sustainability of systems. It determines a system’s ability to persist over the long term, supporting biodiversity in ecological contexts and social well-being in human communities.
Examples of Resilience
Components of Resilience
- Resistance: This is the ability of a system to withstand external pressures without significant alteration to its structure or functionality. In ecological terms, this could mean a forest resisting pest infestations; socially, it could be a community maintaining its cultural integrity despite economic pressures.
- Recovery: Recovery involves the speed and extent to which a system returns to its original state after being disturbed. For example, a coral reef might recover from bleaching if the water temperature stabilizes, or an economy might rebound after a financial crash.
- Adaptation: Adaptation refers to the ability of a system to adjust its responses to changes and new conditions in a way that it can maintain function. This could be a species evolving new reproductive strategies in response to climate change or a company adopting new technologies to survive market changes.
Importance of Resilience
Resilience is essential for the sustainability of systems. It determines a system’s ability to persist over the long term, supporting biodiversity in ecological contexts and social well-being in human communities.
- Ecological Resilience: For ecosystems, resilience ensures the continuation of services such as clean air and water, food supply, and recreational benefits. It also supports biodiversity, which is crucial for ecological balance and function.
- Social Resilience: In social systems, resilience helps communities manage and recover from challenges such as natural disasters, economic crises, or social upheaval. It is key to a society's ability to sustain cultural heritage, economic stability, and social health.
Examples of Resilience
- The Amazon Rainforest: The resilience of the Amazon helps it to recover from occasional droughts and maintain its role as a critical global carbon sink, although ongoing deforestation and climate change pose significant threats to its stability.
- Japanese Society Post-Tsunami: Following the 2011 tsunami and nuclear disaster, Japanese society demonstrated high resilience through effective disaster response, rebuilding infrastructure, and community solidarity, showcasing their capacity to adapt and recover.
- Florida Everglades’ Response to Hurricane Disturbances: The Florida Everglades, a vast wetland system, regularly absorbs the impacts of hurricanes. Its ability to quickly rebound and return to its pre-storm ecological function demonstrates its resilience. This adaptability is crucial for managing water flow, filtering pollutants, and supporting biodiversity.
- The Lodgepole Pine Forests’ Regeneration After Fires in Yellowstone: Following the 1988 wildfires in Yellowstone National Park, Lodgepole Pine forests demonstrated remarkable regeneration. Lodgepole Pines have serotinous cones that require the heat of a fire to open and release seeds, ensuring rapid reforestation after fire disturbances.
- Integrated Crop Management in Malawi: In Malawi, smallholder farmers have adopted integrated crop and pest management practices that diversify crops and improve soil health. These practices build ecological resilience by reducing dependency on chemical inputs and enhancing crop yield stability under variable climatic conditions.
Case Study: Trophic Cascades and Resilience in Yellowstone National Park
Background
Yellowstone National Park's ecological dynamics experienced significant shifts following the extirpation of gray wolves in the early 20th century. The removal of this apex predator led to an unchecked rise in elk populations, which in turn caused overgrazing and significant degradation of vegetation. Recognizing the detrimental impacts, wolves were reintroduced in 1995, which provided a unique opportunity to study trophic cascades and ecosystem resilience.
Trophic Cascades Initiated by Wolf Reintroduction
Top-Down Regulation:
Wolves reintroduced to Yellowstone restored a top-down control in the food web, where their predation on elk and other ungulates helped rebalance the ecosystem. This is a classic example of a trophic cascade, where changes at the top of the food chain cause successive effects down through the trophic levels.
Vegetation Recovery:
With wolves controlling the number of grazing ungulates, the park's flora, particularly willow and aspen around stream areas, began to recover. The resurgence of these plants is critical as it supports a variety of other species and stabilizes riverbanks, which in turn affects aquatic ecosystems.
Enhanced Biodiversity:
The increased vegetation diversity and structure provided habitats for numerous species, from beavers and birds to smaller mammals and insects, showcasing biodiversity recovery through trophic cascades.
Resilience Through Trophic Cascades
Ongoing research in Yellowstone has provided insights into how complex interactions shaped by trophic cascades contribute to the resilience of natural systems. Scientists have used data from Yellowstone to model scenarios in other similar ecosystems, helping predict the outcomes of reintroducing or protecting apex predators.
The wolf reintroduction in Yellowstone serves as a pivotal study in understanding the role of trophic cascades in ecological health and resilience. This case vividly demonstrates how restoring a key species can lead to broad ecological benefits, reinforcing the importance of maintaining natural predator-prey dynamics. It also highlights the critical role of apex predators in maintaining the structure and function of ecosystems, ensuring their ability to respond to environmental changes and recover from disturbances
Background
Yellowstone National Park's ecological dynamics experienced significant shifts following the extirpation of gray wolves in the early 20th century. The removal of this apex predator led to an unchecked rise in elk populations, which in turn caused overgrazing and significant degradation of vegetation. Recognizing the detrimental impacts, wolves were reintroduced in 1995, which provided a unique opportunity to study trophic cascades and ecosystem resilience.
Trophic Cascades Initiated by Wolf Reintroduction
Top-Down Regulation:
Wolves reintroduced to Yellowstone restored a top-down control in the food web, where their predation on elk and other ungulates helped rebalance the ecosystem. This is a classic example of a trophic cascade, where changes at the top of the food chain cause successive effects down through the trophic levels.
Vegetation Recovery:
With wolves controlling the number of grazing ungulates, the park's flora, particularly willow and aspen around stream areas, began to recover. The resurgence of these plants is critical as it supports a variety of other species and stabilizes riverbanks, which in turn affects aquatic ecosystems.
Enhanced Biodiversity:
The increased vegetation diversity and structure provided habitats for numerous species, from beavers and birds to smaller mammals and insects, showcasing biodiversity recovery through trophic cascades.
Resilience Through Trophic Cascades
- Building Ecosystem Resilience: The reintroduction of wolves demonstrated how apex predators enhance ecosystem resilience. By initiating trophic cascades, wolves have helped the Yellowstone ecosystem absorb and adapt to disturbances (e.g., changes in ungulate populations), recover from them, and potentially transform to a more sustainable state.
- Feedback Mechanisms: The interactions between wolves, elk, and vegetation illustrate a negative feedback loop where the presence of wolves keeps elk populations in check, which in turn allows vegetation to thrive, supporting a broader range of biological diversity and promoting ecological stability.
Ongoing research in Yellowstone has provided insights into how complex interactions shaped by trophic cascades contribute to the resilience of natural systems. Scientists have used data from Yellowstone to model scenarios in other similar ecosystems, helping predict the outcomes of reintroducing or protecting apex predators.
The wolf reintroduction in Yellowstone serves as a pivotal study in understanding the role of trophic cascades in ecological health and resilience. This case vividly demonstrates how restoring a key species can lead to broad ecological benefits, reinforcing the importance of maintaining natural predator-prey dynamics. It also highlights the critical role of apex predators in maintaining the structure and function of ecosystems, ensuring their ability to respond to environmental changes and recover from disturbances
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).
- Discuss what factors contribute to resilience and how humans affect these factor
- Explain how lag time can add complexity to modeling and predicting tipping points
- Resilience: The capacity of a system to withstand disturbances while maintaining functionality.
- Key Factors:
- Diversity: Diverse systems have multiple species or elements performing similar functions, creating redundancy. This allows the system to stay stable even if one component is affected.
- Storage Size: Larger storages provide greater buffering capacity, enabling systems to absorb changes and recover more effectively.
- Natural Prairie Systems: Historically, the North American prairies were ecosystems with high biodiversity, including a variety of grasses, herbs, and shrubs, supported by a complex soil ecosystem. This diversity allowed the prairie to be highly resilient to weather variations and disturbances like fire, maintaining ecosystem function and soil fertility.
- Monoculture Systems: In contrast, large areas of these prairies have been converted to monocultures, where only one type of crop (e.g., corn or soybeans) is planted extensively. Monocultures lack biodiversity and are much less resilient. They are more susceptible to pests, diseases, and climate fluctuations, often requiring significant inputs of fertilizers, pesticides, and water to maintain production. The loss of resilience is evident in the increased vulnerability to ecological and economic setbacks.
Size of Storages and Stability
The size of storages within a system, such as water in lakes versus puddles, also affects system stability and the speed of response to environmental changes.
Example: Stability of a Puddle Compared to a Lake:
- Small Storage (Puddle): A puddle represents a small storage of water that is highly susceptible to environmental conditions. It can quickly evaporate or overflow with a small addition of water. Its response to changes is immediate, showing little resistance to weather conditions.
- Large Storage (Lake): In contrast, a lake, with its substantial volume, demonstrates greater stability. Its large size buffers it against rapid changes, such as evaporation or pollution. The larger volume also means that changes like temperature shifts occur more slowly, contributing to a lag in response time but increased overall resilience.
https://criticalangleblog.files.wordpress.com/2016/08/tipping-point.jpg?w=660
Environmental Tipping Points:
- Trigger far-reaching change through reinforcing feedback loops, setting the system on a new trajectory.
- Feedback delays complicate predicting tipping points and increase the complexity of system modeling.
- Lake Eutrophication:
- Extinction of a Keystone Species:
- Removal of elephants from a savannah ecosystem can result in irreversible damage to that system.
- Coral Reef Death: If ocean acidity levels increase, the reef coral dies and cannot regenerate.
1.2.18 Humans can affect the resilience of systems through reducing these storages and diversity.
- Explain how humans can add complexity to the resilience of a system
- Human Actions on Resilience: Human activities, like deforestation and pollution, reduce both the diversity and the size of storages in ecosystems. This reduction limits an ecosystem’s ability to recover from disturbances, weakening overall resilience.
- Examples of Resilience Loss:
- Deforestation: Reduces carbon storage in forests and lowers biodiversity, making ecosystems more vulnerable to disruptions.
- Pollution: Contaminants can lower water quality and soil health, decreasing the resilience of aquatic and terrestrial systems by reducing species diversity and disrupting ecological processes.
- Consequences for Sustainability: Reduced resilience in ecosystems means a diminished capacity to support biodiversity, store carbon, and maintain ecosystem services essential for long-term environmental stability.
- Increased Vulnerability to Invasive Species: With the original habitat disturbed and native species populations reduced, invasive species find it easier to establish and dominate, further shifting the ecological balance.
- Reduced Recovery Capability: Ecosystems with diminished biodiversity and storage sizes are less capable of self-repair and regeneration. This can lead to long-lasting degradation and desertification, conditions that are often irreversible.
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Bolstering Ecosystem Resilience:
- Minimizing Disturbances: Actions like halting deforestation help maintain resilience by reducing ecosystem disruptions.
- Increasing Storages and Diversity:
- Forest Restoration: Planting diverse forests suited to changing climates enhances ecosystem adaptability.
- Agricultural Practices: Techniques that boost soil carbon sequestration strengthen resilience.
- Case Study – American Beaver:
- Benefits: Beavers create wetlands that support biodiversity and enhance water storage.
- Challenges: Their dams can cause flooding in human areas, prompting efforts to balance flood prevention with ecological benefits.
In a remote fishing village in the Philippine archipelago, coastal fishers responded to falling fish stocks by working harder to catch them. The combination of dynamite, longer workdays, and more advanced gear caused stocks to fall faster. On the edge of crisis, this small community decided to create a no-take marine sanctuary on 10% of its coral-reef fishing grounds. This initiative sparked a renaissance of not only their fishery, but also their cherished way of life
You need to understand the relationships between resilience, stability, equilibria and diversity using specific examples to illustrate interactions
image from http://image.guardian.co.uk/sys-files/Guardian/documents/2008/02/05/World_Tipping_map_0502.pdf
Correct use of terminology is a key skill in ESS. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
Key Terms
|
system
system approach reductionism synergy Gaia hypothesis biosphere regeneration matter direct relationship |
emergent properties
model flows inputs outputs ecosystem resilience energy indirect relationship |
transfer
storage processes assemblage matter transformation tipping point dynamic equilibrium |
open system
closed system stock boundaries steady state positive feedback negative feedback stable equilibrium. |
Classroom Resources
| Subtopic 1.2 Systems Powerpoint.pptx |
| Subtopic 1.2 Systems Workbook.docx |
Lake Lanier as a System Case Study
Gaia Hypothesis Activity – Daisy World
Inside Biosphere 2
Making Pancakes as a System activity
Modeling Climate online activity
Case Studies
Be able to identify and describe inputs, outputs, processes, transfers, transformations, and storages of both matter and\ energy for systems at different scales, including specific examples
- Biosphere 2
- plant and animal cells
- individual organism (one producer, one consumer)
- farming systems
- different ecosystems
Useful links
Systems Thinking, Systems Tools and Chaos Theory - Pearson Education Hotlink
Gaia Hypothesis - Physical Geography
The Earths AtmosphereThe Layered Atmosphere - Physical Geography
Biosphere 2 - University of Arizona
National Ice and Snow Databank - National Snow and Ice Center
Climate Interactive Models - Concord Consortium
The Globe Program
Open, Closed & Isolated Systems
Feedback Loops - Starting Point
Sea Ice & Thermodynamics - National Snow and Ice Center
National Ice and Snow Databank - National Snow and Ice Center
What is Albedo? - The Encyclopedia of Earth
The Globe Program
EcoTipping Point Project
Positive and Negative Feedback
Wkst: Feedback Mechanisms
Identifying Feedback Practice
In The News
Hurricane Sandy: Global warming, pure and simple - SALON 31 Oct 2012
Energy Economics in Ecosystems - The Knowledge Project
Earth System Modeling Must Become More Energy Efficient - Eos July 2020
International-Mindedness
TOK:
Video Clips
Systems Thinking, Systems Tools and Chaos Theory - Pearson Education Hotlink
Gaia Hypothesis - Physical Geography
The Earths AtmosphereThe Layered Atmosphere - Physical Geography
Biosphere 2 - University of Arizona
National Ice and Snow Databank - National Snow and Ice Center
Climate Interactive Models - Concord Consortium
The Globe Program
Open, Closed & Isolated Systems
Feedback Loops - Starting Point
Sea Ice & Thermodynamics - National Snow and Ice Center
National Ice and Snow Databank - National Snow and Ice Center
What is Albedo? - The Encyclopedia of Earth
The Globe Program
EcoTipping Point Project
Positive and Negative Feedback
Wkst: Feedback Mechanisms
Identifying Feedback Practice
In The News
Hurricane Sandy: Global warming, pure and simple - SALON 31 Oct 2012
Energy Economics in Ecosystems - The Knowledge Project
Earth System Modeling Must Become More Energy Efficient - Eos July 2020
International-Mindedness
- The use of models facilitates international collaboration in science by removing language barriers that may exist.
TOK:
- Models are simplified constructions of reality-in the construction of a model, how can we know which aspects of the world to include and which to ignore?
- To what extent can it be argued that everything in the world operates as part of a system
Video Clips
In this video Paul Andersen explains how matter and energy are conserved within the Earth's system. Matter is a closed system and Energy is open to the surroundings. In natural systems steady state is maintained through feedback loops but can be be affected by human society.
This is the 2nd segment of a 12 minute overview of the shocking truth about global warming and climate change. This segment deals with the main positive feedback loops in action in Gaia's complex ecosystems: melting of the ice caps, deforestation, melting of permafrost regions of the planet and the destruction of Ehux: a vital marine algae that is a key component of the earth's climate regulation system.
Life is powerful, and in order to understand how living systems work, you first have to understand how they originated, developed and diversified over the past 4.5 billion years of Earth's history. Hang on to your hats as Hank tells us the epic drama that is the history of life on Earth
"A short animated film about the feedback loops likely to lead to catastrophic climate change, by Leo Murray.
From time to time, ecosystems are hit by storms, fires or other types of disturbance. Resilience is the ability of an ecosystem to resist or recover from these events. Resilience preserves ecosystem diversity, productivity and sustainability. Disturbance has more impact on ecosystems that have lost diversity.
For 10,000 years, our world seemed endless. The sky was the limit. But today's world looks much smaller. We've cleared, consumed and polluted our way across the globe. The planet is shrinking. Have we pushed Earth past the tipping point? That's a critical issue the University of Minnesota's Institute on the Environment explores in our second Big Question video. This three-minute multimedia feature draws on research from the article Planetary Boundaries: A Safe Operating Space for Humanity, published this past fall in the journal Nature, and discussed in the current Scientific America
Plenty of people have an opinion on whether the precautionary principle is good or bad, but what exactly is it?
