1.3 energy and equilibria notes

IB Environmental Systems and Societies p. 1
Topic 1: Foundations of environmental systems and societies (16 hours)
1.3 Energy & Equilibria
Significant Ideas:
❖ The laws of thermodynamics govern the flow of energy in a system and the ability to do work.
❖ Systems can exist in alternative stable states or as equilibria between which there are tipping points.
❖ Destabilizing positive feedback mechanisms will drive systems toward these tipping points, whereas stabilizing
negative feedback mechanisms will resist such changes.
Knowledge & Understanding: Use these notes to familiarize yourself with ESS terminology and concepts.
1.3.1 The first law of
thermodynamics is the principle
of conservation of energy which
states that energy in an isolated
systems can be transformed but
cannot be created or destroyed.
Metaphor: Poker game “You can’t WIN”. Explain how this metaphor can be used to
demonstrate the first law (energy = money you bet in the game)
1.3.2 The principle of
conservation of energy can be
modeled by the energy
transformations along food
chains and energy production
systems.
For the following food chain, list all energy types and transformations. Draw arrows
to show where energy is leaving the food chain. This escaping energy = __________
For the following wind turbine diagram, label all energy types and transformations.
Show where any energy is leaving the wind-turbine-house system. This escaping
energy = ____________
1.3.3 The second law of
thermodynamics states that the
entropy of a system increases
over time. Entropy is a measure
of the amount of disorder in a
system. An increase in entropy
arising from energy
transformations reduces the
energy available to do work.
Metaphor: Poker game “You can’t BREAK EVEN” (i.e. you can’t even leave the table
with the amount of money you brought). Explain how this metaphor can be used to
demonstrate the second law.
Original Source: International School of Prague
https://sites.google.com/site/environmentalsystemssocieties/home
Modified by Brad Kremer, May 2017

1.3.4 The second law of
thermodynamics explains the
inefficiency and decrease in
available energy along a food
chain and energy generation
systems
Why is the energy/ or matter
exiting this system of a lower
quality than that entering? Use an
explanation of entropy in your
answer. (think about what it would
take to re-capture the escaped
energy in an effort to reuse it)
1.3.5 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
maintained by stabilizing
negative feedback loops.
Define “open system”:
Give an example of each for a pond ecosystem:
a) matter input:
b) matter output:
c) energy input:
d) energy output:
1.3.6 Negative feedback loops
(stabilizing) occur when the
output of a process tends to
reverse the direction of the initial
change – it counteracts
deviation.
Describe a negative feedback loop that would apply to the following scenarios:
a) The effect of studying/not studying on grades and student motivation to continue
working (or not)
b) The feeding relationship between wolves and rabbits and how the population of
each is stabilized

1.3.7 Positive feedback loops
(destabilizing) will tend to
amplify the initial change and
drive the system toward a
tipping point where a new
equilibrium is adopted.
Describe a positive feedback loop that would apply to the following scenarios:
a) A person who has gained a lot of weight, who tries and succeeds at losing the
weight and getting in shape.
b) Knowing that ice reflects a great deal of solar energy (high Albedo), while
conversely water absorbs a great deal of solar energy (low Albedo); melting ice caps
around the world will increase the temperature of the worlds oceans.
1.3.8 The resilience of a system,
ecological or social, refers to its
tendency to avoid such tipping
points and maintain stability.
Can people show resilience? Give an example of a country or culture that has shown
resilience in the presence of a major stressor, such as a natural disaster.
1.3.9 Diversity and the size of
storages within system can
contribute to their resilience and
affect their speed of response to
change (time lags).
How can the diversity of life in the oceans help produce resilience in terms of climate
change?
Why has it taken so long for damage to the world’s oceans to be obvious and
visible?

1.3.10 Humans can affect the
resilience of systems through
reducing these storages and
diversity.
Using water as an example, describe an example where human activity is reducing
the storage and the diversity of life within the storage.
1.3.11 The delays involved in
feedback loops make it difficult
to predict tipping points and add
to the complexity of modeling
systems.
Why might melting ice be considered an example of a delay in a positive feedback
loop? Consider how long it would take to measure changes in solar energy
absorption by the earth’s surface due solely to a reduced amount of polar ice.

Applications & Skills: Treat the following prompts as assessment questions on your IB ESS exam. Use the terminology
and concepts from the notes above to respond to each of these prompts
1.3.AS1 Explain the implications of the laws of thermodynamics to ecological systems.
● Define each law and relate it to the energy availability and flow in an ecosystem i.e. a forest.
● How does the first law allow life to exist on earth at all?
● How does the second law force ecosystems to keep replacing energy it loses?
1.3.AS2 Discuss resilience in a variety of ecosystems.
Example 1:
Possums were introduced to both Australia and New Zealand by European settlers in the 18th century. The impact of
possums on the New Zealand ecosystem was greater than on the Australian ecosystem. The Australian ecosystem, in
this case, proved to be more resilient to the impact of possums compared to the New Zealand ecosystem which became
overrun by possums.
Describe how size of land mass and presence of natural possum predators could explain the above results.
Find a second example, where a change or a stressor produced resilience in one instance, but not in another.
Example 2:

1.3.AS3 Evaluate the possible consequences of tipping points. Provide three examples. (two have been provided)
Ex. 1: Cooking fuel and deforestation in India. Describe/summarize
Ex. 2: Apo Island (Philippines) Fisheries Near-collapse. Describe/summarize
Ex. 3:
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1.3 energy and equilibria notes

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1.3 energy and equilibria notes