Modern Earth Science Principles

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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 and Earth scientists are used to dealing with this messy and highly complex system. But you are not, so lets 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).

Schematic of the The Earth System consisting of the Geosphere (=Lithosphere), the Biosphere, Hydrosphere and Atmosphere
The Earth System consisting of the Geosphere (=Lithosphere), the Biosphere, Hydrosphere and Atmosphere.

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 increasing 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 each other 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.

Big Data

The considerable threat of events such as sea level rise, hurricanes and tsunami to humankind 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. We will introduce you to a lot of data in this course. In the coastal zone, for example, satellite data provide elevations at centimeter accuracy and we can monitor how processes such as sea level rise and hurricanes are impacting the shoreline.

So we point out examples of complexity, feedback and Earth Systems in the modules. Whenever you see "Earth Systems, Complexity, Feedback IN ACTION" pay attention!

If you want to read more about how us Professors want you to think, check out Teaching for a Sustainable Future in Undergraduate Courses.

We hope that this course brings a lot of the enthusiasm that is permeating modern Earth science.