Week 2: The Integration of the ESS Analysis and PBL Model
In Week 1 you learned what an Earth System Diagram is and how to do an Earth system science analysis using the Yellowstone fires event. This week you will go a step further and reflect on the Yellowstone fires event from an Earth system science standpoint using Problem-Based Learning.

Problem-Based Learning (PBL) is an instructional methodology using real-world contexts for in-depth investigations of a subject matter. PBL activities start with an ill-structured problem that serves as a springboard to team engagement. Learners use a PBL model to assess what is known, to answer questions, and then to analyze various options before presenting a recommendation or solution.

 Below is a summary of the PBL Model you will be using during this course.

1.      Read and analyze the scenario and situation.
2.      List hypotheses, ideas, or hunches.
3.      List what is known.
4.      List what is unknown.
5.      List what needs to be done.
6.      Develop a problem statement.
7.      Gather information.
8.      Present findings.

The following text will show you how the PBL Model and the ESS analysis are integrated.

PBL Step 1: Read and analyze the scenario and situation.  
PBL uses real-world contexts for in-depth investigations of a subject matter. In this course, you will start with an ill-structured problem regarding a real or potential environmental Earth event such as the Yellowstone fires event, which is contextualized within a scenario and situation. The scenario and situation serve as springboards to engage learners in performing an ESS analysis and other related tasks.

Below is an example of a PBL scenario and situation that could have prompted last week's ESS analysis of the Yellowstone fires event.

Yellowstone Fires Scenario
In Yellowstone National Park, fire seasons usually last from June to early September. In 1988 several factors led to an abnormal fire season. During June of 1988, the normal rainfall ceased. Drought conditions with little to no rain, high temperatures, and unusually high winds prevailed. Fires were started by lightning or human interaction, and by July 21 many thousands of acres had burned. The Yellowstone National Park fires of 1988 were the largest series of fires in the Northern Rockies during the last 50 years. The fires of 1988 led to an intense public debate regarding the National Park's policy of letting fires started by natural causes burn to their natural conclusion.

Situation
Your team has been contacted by a coalition of concerned government agencies to help them resolve the debate regarding the National Park's policy of letting fires burn to their natural conclusion. The coalition is particularly interested in your recommendations for a new policy that will be based on your analysis of the fire's impact on living things, air, land, and water.

As you can see, putting the Yellowstone fires event into a PBL context creates an additional challenge beyond the cause and effect observations you read about in the Week 1: An Introduction to an ESS Analysis reading. The Yellowstone PBL Scenario and Situation contain complex issues, conflicts, puzzles, decisions, or circumstances from real-world experiences that get learners into the habit of posing such questions, examining data, analyzing, and framing possible explanations in terms of Earth system science.

PBL Step 2: List your hypothesis, ideas, or hunches.
The second step of the PBL Model is to list your hypothesis, ideas, or hunches about the event from an Earth system science standpoint. You could begin with an original hypothesis (also called ideas, theories, or hunches) regarding the event > sphere, sphere > event, and sphere > sphere interactions. For example, how do the fires impact the atmosphere? How does feedback from the atmosphere affect the fires? You could also look for the interrelationships between the spheres: how does the hydrosphere affect the biosphere, and so on.

Below is an example of a hypothesis (ideas) that could have been written concerning the Yellowstone fires event.

The Yellowstone fires were started by lightning or by humans. Smoke and heat from the fires filled the atmosphere, blocking sunlight and perhaps causing rain (hydrosphere) downwind from the fires. The flames and heat from the fires destroyed all the plants and animals (biosphere) in its path. The ground (lithosphere) was heated and turned black. Products from the fire fell into surrounding water (hydrosphere) and altered the pH. These short-term impacts can have long-term consequences such as increased erosion (lithosphere) due to increased rains (hydrosphere) and little vegetation (biosphere) to hold the ground in place. The pH changes in the water can damage aquatic life (biosphere).

PBL Step 3: List what is known.  
The third step of the PBL Model is to list what is known. To integrate this step with the ESS approach, you could do an ESS analysis of the event that contains not only your current theories and ideas about forest fires but also the reasons supporting that thinking. At this point, you would only need to list what you already know from the scenario and from your prior knowledge. No research would need to be completed during this step. You should be identifying what you believe to be true and your reasons for those beliefs.

When doing the ESS analysis, you should consider the effects of this Yellowstone fires event on each of Earth's spheres and the resulting impact of the spheres on one another. You do this by providing detailed accounts of all the impacts, causes, and changes (revealing your understanding of the interrelationships between and among the event and the spheres in the Earth System Diagram) that led your conclusions put forth in your hypothesis statement.

Link to the examples listed below. Pay attention to the various ways that you can post your interactions. These examples represent a few of the many interactions that could have been discovered during an ESS analysis of the Yellowstone forest fires event. Review the Yellowstone ESS analysis interactions that you posted in your journal last week. How do your interactions compare to those in the links below? Are some of yours the same? Are they different? Look at how the examples linked below include more detail and explanation than the ones in the Week 1: An Introduction to an ESS Analysis reading and think about how you could now revise your ESS analysis so that your explanations go deeper into the science behind the interactions. Focus on how you can write ESS analyses that explore the “why” and the “how” of the science behind the various interactions that occur.

• Event to Sphere Interactions

• Sphere to Sphere Interactions

• Causal Chains

Remember, the examples included in the links above are NOT ALL the possible event > sphere, sphere > event, and sphere > sphere interactions or causal chains that could have occurred as a result of the Yellowstone forest fires event. These are merely a few examples of what seem to be some reasonable causes and effects. There are many other possibilities.

Note that many of the interactions between the Yellowstone forest fires and the spheres result in negative environmental impacts. For example, smoke from the fires can coat the lungs of animals. However, positive environmental effects could occur as the result of the fires. Such positive effects include the removal of excess fuel material in the forests and the preparation of the seeds of some plant species for germination.

Some of the interactions also establish feedback loops. For example, the E > H interaction leads to the continuation of the fire. As the fires burn, they dry vegetation around them, thus creating more fuel for the fire. This positive feedback loop reinforces the burning of the forest fires. A negative feedback loop that lessens the intensity of the fires is established when ash from the fires is carried into the atmosphere and forms condensation particles for water vapor. These condensation particles eventually form clouds that release precipitation. The precipitation can put out the forest fires.

Remember to keep in mind as you list event > sphere, sphere > event, and sphere > sphere interactions that it is important for you to be able to explain why or how the interactions occur. For example, the L > B interaction does not merely state, "A decrease in vegetation may have resulted in increased erodibility of soil." It gives the reason, "because there were fewer roots to hold the soil in place." Such explanations display your understanding of the science behind the interactions. These explanations are valuable for you and others because they make your "Why?" or "How?" thinking visible, and they often lead you to think about additional ESS interactions.

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Maintained by ESSC Team
Last updated July 27, 2000

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