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Complex Earth Systems

The terms "Earth System Science" and "Systems Thinking in Earth Science" and "Complex Systems of the Earth" have been used to refer to at least four distinct, but interrelated, concepts. All are of interest in geoscience education. The first concept, usually referred to as "Earth System Science," refers to the study of the connections and interactions between the atmosphere, hydrosphere, biosphere, cryosphere (ice and snow), solid Earth, and anthroposphere (humanmade objects and processes), as contrasted with the traditional disciplinary study of the individual components separately (Ireton et al, 1996). The study of how evolving life forms changed the composition of the atmosphere is an example of an Earth System Science inquiry. The second concept contrasts the observational complexity of the Earth, in which an observable is likely to result from multiple intertwined causality chains, versus the school-taught experimental method, in which one or two manipulated variables are the only significant influences on a small number of responding variables. For example, an observed change in average atmospheric temperature may reflect changes in solar radiation budget, changes in atmospheric composition, or changes in the Earth's albedo-or all of the above. The third "systems" concept draws on the discipline of systems dynamics (Ford, 1999), and focuses on flows of matter and energy from reservoir to reservoir, the influences on those flows, and the negative and positive feedback loops that drive reservoirs towards constancy or extremities. Atmospheric temperature rises, which causes more evaporation, which causes an increase in atmospheric water vapor concentration, which causes an additional rise in atmospheric temperature through the greenhouse effect, which causes more evaporation, and so on; a positive feedback loop. The final "complex systems" concept pertains to Earth processes that are not deterministic but that can be modeled with a statistical element, including fractal phenomena and deterministic chaos (Turcotte, 2006). Many earth phenomena follow fractal distributions, including coastlines, drainage networks, fragmented rocks, planetary craters, and earthquakes (Turcotte, 1997).

On the topic of complex systems and systems thinking in geosciences, we wish to know:

  • How can geoscience educators, themselves educated in a disciplinary stovepipe such as geology or atmospheric sciences, raise a next generation of both specialists and public who think about the Earth as a single integrated system?
  • How do experts learn about complex systems? In particular, what are the relationships among their observations of the natural system, their development of a conceptual model or theory, and their interactions with digital models of the system?
  • How does the human mind think about a system in which any given observation may be the result of multiple intertwined causality chains, rather than the straightforward cause-and-effect linkage that is implicit in the simple experiments that students typically do in lab courses?
  • How do people think, and learn to think, about positive and negative feedback loops? First, how do we think qualitatively about the direction of influence of such feedbacks, and then, how to do we refine that understanding into a quantitative understanding that can be used to build predictive models of parts of the Earth system?
  • In the Earth system, many observations result from a combination of eternal laws of chemistry and physics superimposed upon the history of what has previously happened; how do geoscientists disambiguate effects of process from effects of prior history, and how can students learn to do this?

Ben-Zvi-Assaraf and Orion (2005a, 2005b) have studied junior high students' understanding of the water cycle, through a combination of Likert-type questionnaires, classroom observation, analysis of student drawings and concept maps, and semi-structured interviews. They have identified a set of emergent characteristics of systems thinking, documented the frequency of each type of thinking in their study population, and begun to unravel the interdependencies among the systems thinking components. For example, 70% of students could identify the components of the system and the processes within it. But only 30-40% were considered to understand the cyclic nature of the system, based on their response to probes such as "In the water cycle, the beginning point is the oceans and its end point is the underground water" (Ben-Zvi-Assaraf & Orion, 2005a, p. 371). Cyclic perception emerged only among students who had previously developed an ability to identify dynamic relationships within the system, as indicated by their response to probes such as "Underground water is similar to underground lakes" (Ben-Zvi-Assaraf & Orion, 2005a, p. 368).

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Cited References

Ben-Zvi-Assaraf, O. and Orion, N. (2005a). A study of junior high students' perceptions of the water cycle. Journal of Geoscience Education, 53, 366-373.

Ben-Zvi-Assaraf, O. and Orion, N. (2005b). Development of system thinking skills in the context of Earth System Education. Journal of Research in Science Teaching, 42, 518-560.

Ireton, M.F., C.A. Manduca, and D.W. Mogk (1997). Shaping the Future of Undergraduate Earth Science Education: Innovation and Change Using an Earth System Approach, Workshop report from the American Geophysical Union: 61pp.

Ford, A. (1999). Modeling the Environment: An Introduction. Washington, DC: Island Press.

Turcotte, D. L. (1997). Fractals and chaos in geology and geophysics. Cambridge: Cambridge University Press.

Turcotte, D. L. (2006). Modeling Geocomplexity: "A New Kind of Science". In C. Manduca and D. Mogk (Eds.), Earth & Mind: How Geoscientists Think and Learn about the Earth. Geological Society of America.