The document discusses stock and flow system models in sustainability science, focusing on the global food system, carbon cycle, and climate system. It examines variables affecting food security, human impact on the carbon cycle, and identifies feedback loops and leverage points in the climate system. Various educational resources and related lectures are also available for deeper understanding and practical applications in sustainability.

1. Stock and Flow System Models
in Sustainability Science
Toni Menninger - http://de.slideshare.net/amenning/presentations
• The Global Food System: Sustainability and Food Security
• The Global Carbon Cycle and CO2 Buildup in the Atmosphere
• The Climate System and Global Warming
For an introduction to stock and flow diagrams, see the book Thinking in Systems by
Donella Meadows, or https://www.systemdynamics.org/DL-IntroSysDyn/stock.htm.

2. The Global Food System: Sustainability and Food Security
• Which variables are
related to the
sustainability of the
food system?
• The model is far from
complete. Can you
identify additional
variables?
• Where would you
intervene to increase
food security?

3. The Global Carbon Cycle and CO2 Buildup in the Atmosphere
• How do
humans
modify the
carbon cycle?
• How can we
reduce the
CO2 buildup
in the
atmosphere?

4. The Climate System and Global Warming
Exercise: What are the
drivers of the climate
system?
• Identify positive
(reinforcing) and
negative (balancing)
feedback loops.
• Can you identify
leverage points?

5. The Climate System and Global Warming
Exercise: What are the drivers of the climate system?
In the table, identify the following variables
and mark them in columns A to E:
A) Variables that are drivers of the climate system
(directly influence surface heat/temperature)
B) Variables directly influenced by human agency
C) Variables indirectly influenced by human agency
D) An increase in the variable causes an increase in
global temperature
E) An increase in the variable causes a decrease in
global temperature
Variable name
A B C D E
Solar Output
Distance from Sun
Albedo
Green house gas (GHG)
concentration in the
atmosphere
Extent of ice cover
Ocean acidity
Sea Level
Fossil fuel combustion
Deforestation
Emissions from Agriculture

6. The Climate System and Global Warming
Exercise: What are the
drivers of the climate
system?
• Identify positive
(reinforcing) and
negative (balancing)
feedback loops.
• Can you identify
leverage points?

7. The Climate System and Global Warming
Exercise: What are the drivers of the climate system?
In the table, identify the following variables
and mark them in columns A to E:
A) Variables that are drivers of the climate system
(directly influence surface heat/temperature)
B) Variables directly influenced by human agency
C) Variables indirectly influenced by human agency
D) An increase in the variable causes an increase in
global temperature
E) An increase in the variable causes a decrease in
global temperature
Variable name A B C D E
Solar Output X X
Distance from Sun X X
Albedo X ? X X
Green house gas (GHG)
concentration in the
atmosphere
X X X
Extent of ice cover X X
Ocean acidity X
Sea Level X
Fossil fuel combustion X X
Deforestation X X
Emissions from Agriculture X X

8. Stock and Flow System Models
in Sustainability Science
© by Toni Menninger MSc. Use of the present materials for educational purposes permitted.
Questions or comments please email toni.menninger@gmail.com
Related lectures and problem sets available at http://www.slideshare.net/amenning/presentations/:
• The Human Population Challenge
• Energy Sustainability
• World Hunger and Food Security
• Economics and Ecology
• Exponential Growth, Doubling Time, and the Rule of 70
• Case Studies and Practice Problems for Sustainability Education:
• Agricultural Productivity, Food Security, and Biofuels
• Growth and Sustainability