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Sustainicum Collection

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Resource facts

  • Independent of the number of students
  • Up to 3 lecture units
  • English

Resource Description

Climate Change (Earth Sciences - Simulation)(Resource ID: 236)

Climate Change This is a model of energy flow in the earth, particularly heat energy. It shows the earth as rose colored, and the surface of the planet is represented by a black strip. Above the strip there is a blue atmosphere and black space at the top. Clouds and carbon dioxide (CO2) molecules can be added to the atmosphere. The CO2 molecules represent greenhouse gases that block infrared light that is emitted by the earth. Clouds block incoming or outgoing sun rays, influencing the heating up or cooling down of the planet. NetLogo is a multi-agent programmable modeling environment. It is used by tens of thousands of students, teachers and researchers worldwide. It is authored by Uri Wilensky and developed at the CCL. You can download it free of charge. http://ccl.northwestern.edu/netlogo/

 

WHAT IS IT?

This is a model of energy flow in the earth, particularly heat energy. It shows the earth as rose colored, and the surface of the planet is represented by a black strip. Above the strip there is a blue atmosphere and black space at the top. Clouds and carbon dioxide (CO2) molecules can be added to the atmosphere. The CO2 molecules represent greenhouse gases that block infrared light that is emitted by the earth. Clouds block incoming or outgoing sun rays, influencing the heating up or cooling down of the planet.

HOW IT WORKS

Yellow arrowheads stream downward representing sunlight energy. Some of the sunlight reflects off clouds and more can reflect off the earth’s surface.

If sunlight is absorbed by the earth, it turns into a red dot, representing heat energy. Each dot represents the energy of one yellow sunlight arrowhead. The red dots randomly move around the earth, and its temperature is related to the total number of red dots.

Sometimes the red dots transform themselves into infrared (IR) light that heads toward space, carrying off energy. The probability of a red dot becoming IR light depends on the earth’s temperature. When the earth is cold, few red dots generate IR light; when it is hot, most do. The IR energy is represented by a magenta arrowhead. Each carries the same energy as a yellow arrowhead and as a red dot. The IR light goes through clouds but can bounce off CO2 molecules.

There is a relation between the number of red dots in the earth and the temperature of the earth. This is because the earth temperature goes up as the total thermal energy is increased. Thermal energy is added by sunlight that reaches the earth as well as from infrared (IR) light reflected down to the earth. Thermal energy is removed by IR emitted by the earth. The balance of these determines the energy in the earth, which is proportional to its temperature.

There are, of course, many simplifications in this model. The earth is not a single temperature, does not have a single albedo, and does not have a single heat capacity. Visible light is somewhat absorbed by CO2 and some IR light does bounce off clouds. No model is completely accurate. What is important is that a model reacts in some ways like the system it is supposed to model. This model does that, showing how the greenhouse effect is caused by CO2 and other gases that absorb IR.

HOW TO USE IT

The SUN-BRIGHTNESS slider controls how much sun energy enters the earth’s atmosphere. A value of 1.0 corresponds to our sun. Higher values allow you to see what would happen if the earth was closer to the sun, or if the sun got brighter.

The ALBEDO slider controls how much of the sun energy hitting the earth is absorbed.
If the albedo is 1.0, the earth reflects all sunlight. This could happen if the earth froze, and it is indicated by a white surface. If the albedo is zero, the earth absorbs all sunlight. This is indicated as a black surface. The earth’s albedo is about 0.6.

You can add and remove clouds with buttons. Clouds block sunlight but not IR.

You can add and remove greenhouse gases, represented as CO2 molecules. CO2 blocks IR light but not sunlight. The buttons add and subtract molecules in groups of 25 up to 150.

The temperature of the earth is related to the amount of heat in the earth. The more red dots you see, the hotter it is.

THINGS TO NOTICE

Watch a single sunlight arrowhead. This is easier if you slow down the model using the slider at the top of the model. You can also use the WATCH A RAY button.

What happens to the arrowhead when it hits the earth? Describe its later path. Does it escape the earth? What happens then? Do all arrowheads follow similar paths?

THINGS TO TRY

  1. Play with the model. Change the albedo and run the model. Add clouds and CO2 to the model and then watch a single sunlight arrowhead. What is the highest earth temperature you can produce?

  2. Run the model with a bright sun but no clouds and no CO2. What happens to the temperature? It should rise quickly and then settle down around 50 degrees. Why does it stop rising? Why does the temperature continue to bounce around? Remember, the temperature reflects the number of red dots in the earth. When the temperature is constant, there are about as many incoming yellow arrowheads as outgoing IR ones. Why?

  3. Explore the effect of albedo holding everything else constant. Does increasing the albedo increase or decrease the earth temperature? When you experiment, be sure to run the model long enough for the temperature to settle down.

  4. Explore the effect of clouds holding everything else constant.

  5. Explore the effect of adding 100 CO2 molecules. What is the cause of the change you observe? Follow one sunlight arrowhead now.

Learning Outcomes
The simulation model "CLIMATE CHANGE" is an example of common features of complex systems. It shows the interaction of carbon dioxide (CO2) molecules that block infrared light that is emitted by the earth and clouds that block incoming or outgoing sun rays, influencing the heating up or cooling down of the planet.
Relevance for Sustainability
Sustainability requires knowledge on the functioning of complex systems. To foster this knowledge multi-agent programmable modeling environments like NetLogo or Starlogo are the best choice to understand the features of complex systems and to experience that by doing easy and fun experiments.
Related Teaching Resources
No specific previous knowledge / related resources required
Preparation Efforts
Low
Access
Free
Sources and Links

Source
http://ccl.northwestern.edu/netlogo/index.shtml

How to cite
If you mention this model in a publication, the authors ask that you include these citations for the model itself and for the NetLogo software:

  • Tinker, R. and Wilensky, U. (2007). NetLogo Climate Change model. http://ccl.northwestern.edu/netlogo/models/ClimateChange . Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL.
  • Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/ . Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL


Credits and references
This model is based on an earlier version created in 2005 by Robert Tinker for the TELS project.

Literature

Manual: http://ccl.northwestern.edu/netlogo/docs/NetLogo%20User%20Manual.pdf

Tisue, S., & Wilensky, U. (2004, updated 2013). NetLogo: Design and implementation of a multi-agent modeling environment . In Proceedings of the Agent 2004 Conference on Social Dynamics: Interaction, Reflexivity and Emergence, Chicago, Illinois, October 2004. http://ccl.northwestern.edu/papers/2013/netlogo-agent2004c.pdf


In addition the Software “StarLogo” http://education.mit.edu/projects/starlogo-tng is recommended. A simulation and modelling program developed at MIT - Massachusetts Institute of Technology enabels users to create simulations without programming knowledge. Detailed tutorials: http://education.mit.edu/projects/starlogo-tng/learn

Comments Write Comment

Author

Pfosser Ruth (FAS.research)

Contact

Ruth Pfosser
ruth.pfosser(at)fas.at
This teaching resource is allocated to following University:
BOKU - University of Natural Resources and Life Sciences Vienna
Institution:
FAS.research - Understanding Networks
Date:

License

Creative Commons
BY-NC-ND

Teaching Tools & Methods

  • Computer program
  • Simulation program
  • Simulation