Week 2: An Introduction to an ESS Analysis

Week Two: An Introduction to an ESS Analysis
Earth system science is conducted by examining each event to sphere, sphere to event, and sphere to sphere interaction. This approach is referred to as an "Earth system science analysis" or an "ESS analysis."

An ESS analysis is done in three steps, which include looking at

how the event affects each of the spheres;
how the spheres affect the event; and
how the spheres affect each other.

Because you will be performing ESS analyses in this course, you should read through the following information as it provides an overview of how to do each step of the ESS analysis. The purpose of this introduction is to get you thinking about the types of interactions that can occur. The forest fires that occurred in Yellowstone National Park, Wyoming, in 1988 is used as the event for this introduction. As you go through the step-by-step process, you should post your ideas for each of the steps in your journal.

When posting your analysis ideas, abbreviate the event with the letter "E" and abbreviate each sphere using the first letter of its name (atmosphere = A; biosphere = B; etc). Use a single-headed arrow (>) to indicate the direction of effects. For example, the effects of the event on the hydrosphere should be written as "E >H".

Step 1: Event > Sphere Interactions

How could the event (Yellowstone fires) affect each sphere? The answers to this question are the event > sphere impacts. Refer to the Earth System Diagram below to help you think about the types of interactions that could occur.

Consider how the Yellowstone fires might affect the spheres, beginning with the atmosphere. Remember to write your additional ideas in your journal.

E > A
The fires created tremendous heat, developed fast rising columns of heated air, which in turn brought in more air at the base of the fires, dropped the humidity in the area of the active fire to near zero, and made dense smoke, which actually traveled hundreds of miles.

There were certainly other impacts on the atmosphere besides this one. What ones can you think of that might be added to the list?

E > H
Ash from the fires fell into the ponds, lakes, and streams.

What impacts might you expect the event to cause in the hydrosphere? Is the effect of burning embers from the falling debris landing in the streams worth considering?

Don't worry about getting “all” the interactions; you probably won't be able to. Just focus on identifying one or two impacts. And remember, the impacts on some spheres will be more numerous than on others. That's not a problem.

E > B
The fires burned and killed the plants and trees, as well as the animals who could not escape, in the area.

How else did the fires affect the biosphere at Yellowstone National Park? There are the obvious "destructive" effects on plant and animal life as well as on habitat. You might also consider the "beneficial" effects of burning off accumulated debris on the forest floor and similar occurrences that might be considered advantages of the burning. Add some of these to your journal.

E > L
The forest fires burned the parts of the soil where the plants put down their roots.

Lastly, what effects might these fires have had on the lithosphere? Here, you might consider the effects on soils, or perhaps even on the water levels of the geysers and hot pools the Yellowstone National Park is so famous for.

Step 2: Sphere > Event Interactions

How could each sphere affect the event? The answers to this question are the sphere > event impacts.

Take another look at the Earth System Diagram above. Notice that the arrows go not only from the event to each sphere but also from the spheres back to the event. While looking at the diagram, ask yourself, "If this happened to the biosphere because of the fires, how might that have an effect on the fires themselves?" For example, if the fires cause the forest floor debris to be burned off in the biosphere, how might that impact the fires themselves? Clearly, the fires would be removing the fuel necessary to keep them burning. So, a statement like, "The leaf litter was burned by the fires, thus diminishing the amount of fuel available to keep the fires burning in that area” might be an appropriate B > E interaction.

Look at each set of possible changes the fires might make on each sphere. If they occurred, how might these changes in turn affect the fires? Consider whether these changes have short-term or long-term effects.

Step 3: Sphere > Sphere Interactions

How could each sphere affect the other spheres? The answers to this question are the sphere > sphere interactions.

Now that you have a general idea of how the event and spheres can impact and affect one another, it is time to introduce one more level of interaction. Take a look at the version of the Earth System Diagram below. You will refer to this version of the Earth System Diagram when you do ESS analyses in the future. Notice the additional arrows going to and from each of the spheres. These additional arrows indicate another set of interrelationships that are influenced by the event.

If certain changes were created in one sphere by the event, how might those changes influence change in the other spheres? Once the event has had an impact on or made a change in a sphere, for example the lithosphere, how does that influence the way the lithosphere now interacts with the other spheres? As an example, the fires burned the soil (lithosphere) to a depth of several inches or more in certain "hot spots." What effect do you think that will have when it finally starts raining and there is runoff to the streams (hydrosphere)? If there were burning embers put into the atmosphere that eventually fell back into the streams (hydrosphere) how might that blackened debris have affected the aquatic invertebrates and fish (biosphere) that survived the event?

Try to see what interactions you can find among the different spheres. Think about what changes might have occurred in each sphere as a result of the Yellowstone fires. Add these effects to your ESS analysis.

If you find yourself questioning, "If the hydrosphere is damaged by the falling charred debris and that does major damage to the fish, then how does that affect the biosphere?" that's a good sign because it means you're beginning to look at the way the world works. It just seems to be one great collection of interacting spheres and then along comes a new event and the process of balancing starts over again.

At this point, you will not have all the possible interactions written down by any means. Furthermore, it is very unlikely that each of your classmates has the same set of interactions written down that you do and that is not a problem either. As you analyze events in the future, the list of interactions each one of you contributes will simply reflect your own individual backgrounds and experiences. There isn't any RIGHT answer for these ESS analyses or any COMPLETE answer that you are trying to attain. You just need to be able to explain and support why you think something may be an impact.

Keep in mind as you list the interactions that it is important for you to offer scientific reasoning or scientific explanations to explain why or how the interactions occur. Scientific reasoning and scientific explanations are prior knowledge from your own experience, learned from somewhere else, etc. Such reasoning and 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.