Modern Earth Science Principles
The Earth System
Many of you have not had an Earth Science class before so it is necessary to prepare you for a new way of thinking that you will be practicing throughout the class.
The Earth is a wonderful, big messy pile of rock, water, and air with life teaming all over it. Earth scientists are used to dealing with this messy and highly complex system, but you are not. So let's simplify things to start. The Earth is an integration of four systems or spheres: air, water, land, and life. Technically speaking these are known as the atmosphere (air), hydrosphere (water), lithosphere (land) and biosphere (life).
Modern Earth Science is focused on the connections between the spheres and this approach is extremely relevant in this course. Water is a basic human right, and climate change combined with the increase in global population and worsening pollution, are going to make clean drinking water an increasingly scarce commodity in coming decades. Thus human survival (the biosphere) is going to depend more and more on access to this precious part of the hydrosphere. As you will learn the water cycle involves the atmosphere (rain and snow) and the lithosphere (soil and rock) where groundwater resides in aquifers. During the course of the semester, we will consider the interactions between the different Earth systems on a continual basis. In Units 1 and 2, we consider the lithosphere, hydrosphere and atmosphere and how they interact with one another in terms of how water flows on the Earth's surface and underground. In Unit 3 we focus on how humans use (and misuse) water and how politics enters into groundwater resources.
The techniques of modern Earth sciences: How Earth scientists think
Because Earth scientists are continuously working at the intersection between the spheres, their field is by necessity an integrative one, meaning that the techniques that they use are built upon the connections the earth, air water, and life. As we mention above, these connections are inherently complex and subject to great changes over time. Thus Earth scientists are accustomed to dealing with complexity, fluctuation, and uncertainty and you will see good examples of each of these factors throughout the semester.
Feedbacks and Linearity
The complex connections between the involve what are known as “feedbacks.” These are mechanisms that dampen or accelerate the impact of one process on another. Sounds complex? The best way to explain a feedback is to give an example and the best example involves the growth of ice such as in a glacier. Ice reflects sunlight better than almost any other material on Earth, and in reflecting sunlight, it lowers the amount of energy from sunlight absorbed by Earth, which makes it colder. If the Earth becomes colder, glaciers may grow, covering more area and thus reflecting even more insolation, which in turn cools the Earth further. Thus cooling instigates ice expansion, which promotes additional cooling, and so on — this is clearly a cycle that feeds back on itself to encourage the initial change. Since this chain of events furthers the initial change that triggered the whole thing, it is called a positive feedback. There are also examples of negative feedbacks whether the chain slows the change that triggered the events. We will point examples out to you in the modules.
Moreover, when you really get involved in studying processes on Earth, you will find out that some variables are related to one another in a linear fashion, for example, an increase in variable X leads to a doubling of variable Y, but in fact, many processes are related in a non-linear way. At the level of this course, we will not be exploring linearity and non-linearity in much detail, and as you can imagine most of the processes we discuss are non-linear.
In common usage, we think of the word complex meaning something like "difficult to solve" or "multifactor". In this course and across the disciplines of social, earth, and biological sciences, however, complexity has a more specific meaning: a complex system like the food system has many interacting parts with multiple levels of organization (think of fields within farms within regions within world climates, in interaction with markets and transportation networks, government policies and regulation, and small and large food companies). All of these interacting parts, or many of them, may have interactions consisting of linear or nonlinear relationships and feedbacks we've just considered above. Therefore the behavior of the system as a whole may be initially difficult to understand and may produce unexpected, sudden, and/or self-organizing and self-reinforcing behavior. In our daily lives we may be used to systems like human-designed machines, math problems, daily routines, or other processes that are designed to be very non-complex, like the way we control the motor of a car or the handlebars of a bicycle driving down the street, or play a musical instrument using simplified systems like vibrating strings or reeds in a deliberate way. We hope very much that a car, a piano, or a clarinet do NOT produce unexpected behavior or nonlinear feedbacks, but we do expect that from a regional food system or a local agricultural landscape. Complex systems may, therefore, require new skills to appreciate and understand, and it's our hope that by learning about the multiple interacting parts of food systems, from soil to rainfall to the sandwich at the local deli, you will gain appreciation for the need to study complex systems, especially those combining humans and the global environment, that are currently faced by sustainability challenges. Furthermore, by the end of the course, we want you to be able to apply skills in analyzing complex systems to develop scenarios for better human management of complex environmental systems. To appreciate complexity it is necessary for us to practice systems thinking, something that will be addressed in the first module. It's also important to not become overwhelmed by complexity and to have frameworks and methods that allow us to digest complexity and consider scenarios within systems. Throughout the course, we'll try to flag when we are dealing with systems approaches or a reading or module section that focuses on complexity. We may directly point out examples of complexity, feedback and Earth Systems in the modules. Whenever you see "Earth Systems, Complexity, Feedback IN ACTION" pay attention!
You can find a nice description of complexity including definitions from a variety of authors at Developing Student Understanding of Complex Systems in the Geosciences.
The considerable threat of food shortages, access to clean drinking water for large numbers of people and other massive problems facing humanity, has provided a boost to the Earth sciences, broadly defined to include geoscience, geography, atmospheric science, and oceanography. Massive datasets are now available to study the Earth and with technology that can handle terabytes of data in a heartbeat, this is an extraordinarily exciting time to be an Earth scientist. In the class, there are several examples where real data are used in activities. For example, in Module 2 you will look at the Life Cycle Analysis (LCA) of Potato in smallholder Andean and North American production systems and in Module 5 you will classify the crops used to produce the current top 20 world commodities and interpret how vulnerable they are to climate change, how they have changed since 2000 and what factors might explain the change in production.
We hope that this course brings a lot of the enthusiasm that is permeating modern Earth science.