Before you begin this course, make sure you have completed the Course Orientation.
You are just beginning Unit 1 of the course. This unit consists of a single lesson, Lesson 1, which will introduce you to some core concepts we will build on throughout the rest of the course.
When I returned to Penn State in 2003, I immediately began to interact with the director of EESI, Sue Brantley. Sue and I quickly realized that we had common interests in the rates of soil formation (Sue) and ancient soil processes (me), so I began to work with her on a national-scale initiative, at the time organized as the Weathering Systems Science Consortium. This initiative evolved through a series of National Science Foundation (NSF)-sponsored workshops and meetings into what became the Critical Zone Exploration Network (CZEN). Since that time, the NSF has funded a network of Critical Zone Observatories (CZO), of which Sue is the principal investigator on one (Shale Hills), and a CZO National Office that I have coordinated and directed for a decade. This Critical Zone course that you are enrolled in evolved from these efforts and you will read reports and scientific manuscripts that were developed through these initiatives.
As you will learn in more detail, the Critical Zone refers to the thin outer veneer of Earth's continents between the top of the vegetation canopy down to the bottom of the fresh groundwater zone —in effect, the zone where most of terrestrial life as we know it thrives, including humanity. Consider a single entity capable of nurturing life, supporting agriculture, cleansing water, buffering atmospheric gas levels, to name a few processes, and you will have considered the Critical Zone. It is this zone, or system, critical to the maintenance of healthy life on Earth, that we will learn about during this course.
Historically, very little transdisciplinary and integrative science has been accomplished in the Critical Zone, primarily because no national-level funding enabled such studies. However, the U.S. National Science Foundation corrected that oversight through the creation and funding of a Critical Zone Observatory (CZO) program in 2007. The CZO program will be terminated in November 2020 but has been replaced by the Critical-Zone Collaborative Network (CZNet), an evolving network of thematic clusters and a coordinating hub that the greater CZ community eagerly watches as it now evolves. Thus you have entered an emerging realm of science, truly a frontier, in which new concepts will be advanced and new discoveries will be made as we progress through this course.
Penn Staters have been fortunate to have the Shale Hills Critical Zone Observatory near the main campus. Take a look at the video clip of my visit to Shale Hills. The video is somewhat outdated since the CZO program expanded to 9 observatories and has subsequently been terminated, but the video is still informative.
For information on the other nine NSF-funded Critical Zone Observatories, visit Critical Zone Observatory [2]. While there be sure to view the 7-minute Introductory video. [3]It, too, is somewhat outdated but provides additional introductory information on the now-terminal Critical Zone Observatory program.
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
In this first lesson, you work through a broad introduction to the Critical Zone, which will include the history and development of the Critical Zone concept. You will find that I have assigned a report from a National Science Foundation (NSF)-sponsored workshop on the Critical Zone and sections from a National Research Council (NRC) book cited in the Critical Zone workshop report. Not only do I want you to understand the term Critical Zone, but I also want you to understand the most basic processes that occur in the zone and to appreciate why it is important to understand the Critical Zone. Furthermore, I want you to read and understand the role that the NSF and NRC play in developing and supporting scientific endeavors in our country — think about how their programs might help your own teaching!
By the end of this lesson you should be able to:
Lesson 1 will take us one week to complete. As you work your way through these online materials for Lesson 1, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 1. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Semester Project Identifying your project region and topic | page 4 | Post to the Lesson 1 - Semester Project Proposal dropbox in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
The Critical Zone encompasses the external or near-surface Earth extending from the top of the vegetation canopy down to and including the zone of freely circulating fresh groundwater. Complex biogeochemical processes combine here to transform rock and biomass into the central component of the Critical Zone—soil. The Zone sustains nearly all terrestrial life including humanity, nonetheless, ever-increasing negative impacts of human society on the Critical Zone continue. Will we allow these impacts to continue unabated, and if so how will our impacts affect humankind and the rest of nature?
The degraded state of Earth's surface has been well documented for example in the United Nations Environment Programme's Millenium Ecosystem Assessment report (2005), [4]and One Planet Many People: Atlas of Our Changing Environment (2005); the Intergovernmental Panel on Climate Change Fifth Assessment Report (2013), and more recent versions [5]; The Penguin State of the World Atlas: Ninth Edition (2012); and, The Atlas of Global Conservation: Changes, Challenges, and Opportunities to Make a Difference (ed., J.L. Molnar, 2010). Hooke et al (Land Transformations by Humans: A review; GSA Today, 2012, v. 22, no. 12, 4-10) summed up some of the topics and tone of these reports concluding that humans have modified more than half of Earth's land surface, that the current rate of land transformation is unsustainable, and that "changes that human activities have wrought on Earth's life support system have worried many people". To many scientists and citizens, these threats to an essential component, i.e. the Critical Zone, of our life support system, have reached an acute level, yet the science of understanding and managing these threats mostly remains embedded within individual disciplines, and the science has largely remained qualitative - there has never been a more important time for a truly international and interdisciplinary approach to accelerate our understanding of Critical Zone processes and how to intervene positively to mitigate threats and sustain and enhance Critical Zone function. All life on Earth relies on humanity embracing balance and sustainability on a global scale.
In this lesson, you will be introduced to Critical Zone science. To accomplish this you will read "The Critical Zone: Earth's Near-surface Environment" and "Frontiers in Exploration of the Critical Zone: Report of a workshop sponsored by the National Science Foundation (NSF)." I stress that this is an introduction. While I want you to grasp key concepts from the readings, I do not want you to fret over every detail — we have plenty of time for that throughout the remainder of the semester. For now, I want you to understand that Critical Zone science truly is multi- and inter-disciplinary — Critical Zone processes are represented by coupled physical, biological and chemical processes — and that an array of scientific expertise is needed to understand the Critical Zone: geology, soil science, biology, ecology, geochemistry, geomorphology, hydrology, to name a few.
Read the following selections:
These readings are also available through Library Reserves.
In this course, a semester project is assigned in order to:
To me, point 1 above is the most important. I sincerely hope that you will engage this opportunity along with my expertise and your energy and creativity to develop a tool for teaching Critical Zone science in your classroom(s). The project is somewhat loosely defined, to be developed through communication between me and each of you, but you will research and study a site or process that exemplifies some aspect of Critical Zone science. Ideally, your project will focus on a locale within your teaching region so that a field trip could be designed if that is appropriate in your school district—with luck a suitable site may exist on your school property! In the end, you will develop and present a ten-page, referenced report and lesson plan for 30% of your final course grade. My philosophy is that if you sincerely and wholeheartedly engage points 1 and 2 above, my evaluation will be easy for me and great for you.
This week you will begin communication with me about your semester project. By the end of Week 3, you will have finalized the region and topic of your project. You should view this communication process as evolutionary, that is, we will probably not converge on a topic in one e-mail or phone conversation. Please adhere to the due dates associated with this project: communicate with me regarding potential project topics during week 1, refine the topic during week 2, finalize topic by week 3. Remember the evolutionary nature of topic development. As with other communications, if you wait until the last minute to discuss the semester project with me, I may not be able to respond to you in a time frame that allows you to adequately consider my comments and meet the deadline.
I've included some examples of well-considered and developed semester projects from some past semesters in which the course was offered and taught (see below under Attachments and a link). The first, by Laurie Syphard, presents a lesson plan that uses data from one of the National Science Foundation's Critical Zone Observatories to lead high school students through a hands-on learning exercise. Laurie is a 2012 graduate of the M.Ed. in Earth Sciences program and has been able to integrate some of the content that is covered in Earth 530 into her work as a freelance science curriculum developer. The second example, by John Smith, is also a lesson plan that in this case uses information you will learn to access during this course - to develop site studies that culminate in a field trip. John graduated from the M.Ed program in August 2013 and has indicated that he left this course with a greater understanding of the Critical Zone, which he intends to share with his students. Third, is an example completed by Adam Renick, a school teacher in San Diego - Adam used his semester project to organize his subsequent program-required "capstone" project: a virtual field trip to Torrey Pines State Park, the site of his semester project study. Click here to see the results of Adam's capstone [14], admittedly several steps beyond what I expect for your semester project, but an excellent example of what can be accomplished during this course to implement in your school curriculum. Feel free to view and study them, but please do not try to reuse them for your project!
Identify your semester project region and topic for your semester project. The region you identify for your semester project will be straightforward: it should lie within a bus ride of your school so that you can realistically consider implementing site visits into your school's curriculum if that seems appropriate. Alternatively, you could study some aspect of Critical Zone science at a nearby site in which you collect data, observations, and photographs that could be presented in your classroom. You will want to develop a topic and site that can engage your students in thinking about Critical Zone science as you will understand it after Lesson 1. If you have some specific expertise or area of interest, you may want to skip ahead to a lesson that engages that expertise/interest to guide your thinking on the semester project. In any case, we will need to discuss the specific site and topic, and you must receive my permission to proceed.
Attachments (optional) must be in Word (.doc) or PDF (.pdf) format so I can open them. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
The identification of your semester project topic in a timely fashion will reflect on your grade for the project. If you adhere to the schedule, you will have begun the path toward an eventual "A." In other words, you will not have negatively affected your grade. If, however, you ignore the schedule, your grade will be adversely affected: 5% lower grade on the semester project for each day you are late.
Attachment | Size |
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Earth530_Semester_Project_example.pdf [15] | 156.25 KB |
Earth_530_semesterproject__example2.pdf [16] | 797.54 KB |
You have reached the end of Lesson 1! Double-check the list of requirements on the Lesson 1 Overview page to make sure you have completed all of the activities listed there.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim.
As introduced in Lesson 1, Critical Zone processes are represented by coupled physical, biological, and chemical processes that involve study by experts in geology, soil science, biology, ecology, geochemistry, geomorphology, and hydrology, to name a few of the relevant sciences. While these various disciplines are equally important for understanding the Critical Zone, they are linked by the presence of soil, considered by many to be the central component of the Critical Zone. This concept is perhaps best illustrated by the SoilCritZone logo shown here: a four-leaf clover-like emblem of yellow (at top, representing atmosphere), green (right, biosphere), blue (left, hydrosphere), and brown (bottom, lithosphere) arcs surrounding the acronym SoilCritZone; the design of the logo symbolizes how soil and the Critical Zone exist within the overlapping region between the four arcs or "spheres." The spheres closely overlap with the state factors of soil formation you will be introduced to later in this lesson: parent material, climate, topography, biota, and age.
Many of you may consider soil to be the mud you played in as a child, the material into which you plant your garden or the dirt you scrape off the bottom of your shoes or wipe from your dog's muddy feet. To most of humanity, soil may even seem to be a nuisance—the word itself has various meanings depending on the usage: as a verb, soil means to make dirty; to disgrace or tarnish; to corrupt or defile; or to dirty with excrement (Free Online Dictionary [17]).
To begin to focus your attention on the positive aspects of soil, please consider the following four definitions. Soil is:
Though the four definitions share common attributes, they do differ. For example, agronomists and most soil scientists focus their studies of soil on the rooted zone, or rhizosphere (approximately to depths of one meter), while the geologist's perspective is much broader and deeper, encompassing the full thickness of material down to the original parent material (shallow to depths up to one hundred meters or more). Nonetheless, most scientists agree that soil is a complex biomaterial that promotes the growth of terrestrial organisms, that it is crucial to life on Earth, and that it is the product of material derived from weathering of parent material, decomposing plant matter, and atmospheric deposition. Furthermore, as soil resources are finite, humanity should view them as non-sustainable and learn to care for and sustain these important resources. For these reasons, we will now turn our attention in Lesson 2 to the study of soil, the "heart" of the Critical Zone.
Browse the following Web site to learn how a consortium of university and government agencies from the European Union focused on Critical Zone studies in Europe and d information to guide the development of better government policies to sustain soil resources.
(Optional) Visit the U.S. Department of Agriculture Soil Resource Management [19] research program's Web site to learn about soil conservation and management, nutrient management, soil water and biology, and other soil-related research in the U.S.
Also, check Soil Education [20] for a wide range of important information regarding soils, including various media that can be introduced into your classrooms.
The Smithsonian's National Museum of Natural History has recognized the societal importance of soil by creating an exhibit that opened in Summer 2008. To learn more about this exhibit, see Dig It! The Secrets of Soil [21]. Be sure to view the new curator-led tour of the exhibit.
Finally, you may also be interested in this beautiful informative brochure [22] created by the Swiss National Science Foundation, in part to observe the 2015 International Year of Soils.
In this lesson, we will focus on soil, the "heart" of the Critical Zone. I am not concerned that you memorize various definitions for soil—instead, I want you to learn that soil consists of mineral and organic matter derived from a variety of sources and that it is vitally important to sustaining life on Earth, including human society. To do this we will examine the basic processes involved in soil formation (the so-called state factors of soil formation), simple scientific approaches to studying and classifying soils, and the global distribution of different types of soils (soil orders). You will learn that soils are not randomly distributed on our planet, but instead, occupy space determined by the overlapping domains of the state factors of soil formation. Ultimately, soil records the overlap of atmospheric, lithospheric, hydrologic, and biologic processes, the innermost workings of the Critical Zone. Finally, you will consider the distribution of soils near your workplace and the implications of the distribution to understanding Critical Zone processes and land use at the site. You will accomplish this by using an online resource that you may want to introduce into your own classroom. In a later lesson, we will apply this knowledge of present-day soils to learn about ancient soils (paleosols) and their importance for understanding Earth history and perhaps Earth's future.
By the end of this lesson you should be able to:
Lesson 2 will take us one week to complete. As you work your way through these online materials for Lesson 2, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 2. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Answer questions about soil erosion | page 3 | Upload your responses to the Lesson 2 - Soil Erosion dropbox in Canvas |
Answer questions about soil orders | page 6 | Upload your responses to the Lesson 2 - Soil Orders dropbox in Canvas |
Short report on the Web Soil Survey | page 7 | Upload your report to the Lesson 2 - Soil Survey dropbox in Canvas |
Discussion—Teaching and Learning About Soil | page 9 | Participate in the Unit 2 - Teaching and Learning About Soil discussion forum in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
Much of Earth's surface is covered by unconsolidated debris overlying hard, unaltered rock. This unconsolidated layer is called regolith. The regolith may have formed in place immediately above unaltered rock, or may have been transported by various physical processes we will discuss in Unit 4. Soil is derived from the physical, chemical, and biological alteration of regolith.
At the simplest level, the presence or absence of soil can be considered as dependent upon whether alteration of regolith (soil formation) occurs faster than soil erosion. Soil erosion occurs naturally but is widely recognized to have been greatly increased by human activities in the Critical Zone—both the natural and human-influenced (or anthropogenic) rates of soil erosion have been well studied and measured.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L2_soilerosion_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L2_soilerosion_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your paper to the "Lesson 2 - Soil Erosion" dropbox (see the lesson folder under the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead, plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful, insightful, and should provide connections between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Soil formation, or pedogenesis, typically happens over long periods of time. The so-called "mineral" component of soil is formed from the weathering, or decomposition, of rocks and minerals. There are two types of weathering: physical and chemical. Physical weathering involves the breakdown of rocks into smaller particles through direct contact with atmospheric heat, moisture, and pressure. The effects of various chemical processes (e.g., atmospheric or biologic) on the size and composition of minerals and rock is known as chemical weathering. Weathering processes will be further explored in our landforms unit.
The rates of soil formation have not been as well characterized as soil erosion rates. This creates an interesting conundrum for scientists and land-use planners interested in the impacts of soil erosion. Though we know there are sites on Earth where soil is eroding at an unsustainable rate, do sites exist where soil is forming at a rate that equals or exceeds the rate of soil erosion? If so, soil erosion may not be an important consideration for these sites when considering land-use issues. Therefore, accurate determinations of soil formation rates under varying conditions are a key question in Critical Zone science.
Soil formation is controlled by five variables in nature. Those variables are:
In addition, most scientists also recognize that humanity, having influenced much of the Critical Zone, represents a sixth factor in soil formation. The varying distribution of these variables in soil formation (also known as the state factors) on Earth's surface, and therefore the differing distribution of physical, chemical, and biological processes dependent upon the distribution and interplay of the state factors, plays a role in soil formation and the development of different types of soil.
Before we progress to learn about the different soil types and their distribution on Earth, I want you to first understand the state factors of soil formation. Please read the following text chapter, which is available through Library Resources:
As you read this, keep in mind that I'd like you to leave this reading assignment able to list the state factors of soil formation. You should also understand the basics of the role each state factor plays in soil formation. Begin to think about the varying distribution of the state factors on a landscape-versus-global scale. Do you think patterns exist in the distribution of the state factors? If so, do these patterns carry over to observable patterns in the distribution of the soil orders?
Soils are characterized in the field in natural exposures, in dug soil pits, or in places where augers can be used to bore holes and obtain samples from the subsurface. Typically soils are described on the basis of the presence of soil horizons and the character of the boundaries between horizons, the texture of the soil based on the size of the soil constituents, the color of the soil material, the structure of the soil, the presence of organic matter and roots, and the hydraulic conductivity. Other relevant characteristics include the geomorphic (landscape) location of the soil (including slope, elevation, aspect), and soil parent material. These characteristics are in turn used to classify soils—we will discuss the classification of soils to the order level, that is twelve soil orders. Before we do, follow each of the links below to learn more about soil sampling and characterization.
You will notice that there is a substantial overlap between the first Weblink shown below and the following four Weblinks. I would like you to visit all of these Web sites but spend no more than two hours total reviewing this information.
Different soil types are variably distributed across Earth's continents, dependent upon the varying relative influence of the state factors of soil formation. These varying soil types are recognized by the characteristics you studied when considering soil description and classification. The various soil types are mappable units; that is, they exist as coherent bodies of similar soil material which eventually merge laterally with other soil types, bedrock, or unaltered sediment. The process by which the distribution of the different soil types are mapped in the field is called soil surveying or soil mapping [38].
The term "soil survey" is also used to describe the published results of soil mapping efforts. Typically these published reports include information about slope, permeability, and drainage characteristics, to name a few and are therefore very important reference manuals in land-use planning and decision making. In the United States, we are fortunate to have a Federal agency which oversees soil mapping, currently named the Natural Resources Conservation Service (NRCS).
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
A wide range of soil classification schemes has been developed by various nations primarily interested in the agricultural aspects of their native soils. Again, you should not spend much more than two hours reviewing this information.
"Teacher's Domain" is a free resource, but you must register with them in order to view more than seven resources. Since we'll point to that resource throughout this course, you may want to take a moment to go ahead and register with them now.
L2_soilorders_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L2_soilorders_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
(Optional) Visit the United States Department of Agriculture (USDA Website [44]).
Soils provide a number of essential goods and services to humanity, including biomass and food production, water filtration, carbon sequestration, and the substrate on which we live our daily lives. Yet the actions of human society present the single largest threat to this essential component of the Critical Zone and Earth system. Negative impacts to soils from human activity include erosion, compaction, salinization, sealing by paving, pollution, and declines in organic matter content and biodiversity. To learn more about threats to soil, visit The Environmental Literacy Council [46]. As you read the short statement there, think about how your own actions threaten the health of soil in your yard, community, and nation. Do you apply herbicides and pesticides to maintain a weed- and pest-free lawn? Do you have a paved rather than gravel driveway? If you have a septic system, do you maintain it and is it operating properly? Do you purchase food grown locally using sustainable agricultural practices? These are just a few of the actions you may take in your lives that preserve the health of soils.
Let's take some time to reflect on what we've covered in this unit!
For this activity, I want you to reflect on what we've covered in this unit and to consider how you might adapt these materials to your own classroom. Since this is a discussion activity, you will need to enter the discussion forum more than once in order to read and respond to others' postings.
You will be graded on the quality of your participation. See the grading rubric [47] for specifics on how this assignment will be graded.
In this lesson on soils, you read about soil formation, the description of soils, and the classification of soils in the United States into twelve soil orders. You also considered the effects of soil erosion on the Critical Zone and how the distribution of the twelve soil orders might relate to the five state factors of soil formation. By now you should understand that soil is a complex material composed of mineral and organic matter, formed by competing processes associated with climate, biota, parent material, topography and time. Soil exists in the overlapping realm between the atmosphere, hydrosphere, lithosphere, and biosphere. It is classified according to need: a geologist studying soil formation rates may have a very different view of soil compared to an engineer building a superhighway or an agronomist trying to understand soil fertility for crop management. Furthermore, due to the increase in human activity on Earth, soil erosion mostly exceeds soil formation rates, thus soil should be viewed as a finite resource that is rapidly being depleted. Finally, you should be well aware that soil maps are available for most of the United States and that they can be very useful, if not critical, for land-use planning and decision making.
With this firm background, throughout the course I want you to remember and contemplate the outstanding question in Critical Zone science, which was introduced in a Lesson 1 reading (Brantley et al. p. 11): can a unified approach be developed to characterize environmental conditions and mechanisms that produce different soil types?
You have finished Lesson 2. Double-check the list of requirements on the Lesson 2 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
Atmospheric processes and climate (primarily precipitation and temperature) may be the most influential of the factors involved in soil formation because they control weathering over large geographic regions. Bedrock parent material is subjected to physical weathering and disintegration through expansion and contraction associated with wide temperature fluctuations. The presence of water enhances this effect through freezing, thawing, and chemical processes—chemical weathering is accelerated under warm climate settings. In addition, solute and particulate (dust) deposition from the atmosphere plays an important role in Critical Zone and soil biogeochemistry. While continents are more impacted by atmospheric deposition, strong contrasts exist between bedrock and atmospheric sources in ocean island soils.
Climate, as one of the state factors of soil formation, is controlled to a large extent by atmospheric processes dependent on the latitudinal position on Earth. To properly understand the varying effects of climate on the Critical Zone, we must understand Earth's atmosphere and the range of phenomena that occurs within it. The focus of our next three lessons (Lessons 3, 4, and 5) is on understanding the atmosphere and climate systems. In Lesson 3, we will explore the basic structure of the atmosphere, the carbon cycle, basic atmospheric chemistry, atmospheric carbon dioxide and greenhouse gases, radiative forcing, and physical climate processes and feedbacks. In Lesson 4, we will turn our attention toward the evolution of Earth's atmosphere and ocean system through geologic time, specifically focused on our understanding of paleoclimatology (ancient climates). In Lessons 4 and 5, we will consider potential lessons from this knowledge of ancient climate and regional climate issues, in particular how this knowledge can aid our predictions of, and planning for, future climate change. Finally, we will consider how all this knowledge of past, present, and future climate processes is linked to soil formation and the Critical Zone, a topic we will return to in the final lesson (Lesson 12) of this course.
I visited the Adirondacks in upstate New York to examine climate, the hydrologic cycle, and some of the ways in which the forests interact with the Critical Zone during the winter season. Take a look at the video clip below of my visit to the Adirondacks.
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
To properly understand the varying effects of climate on the Critical Zone, we must understand Earth's atmosphere and the range of phenomena that occurs within it. In this lesson, we will explore the basic structure of the atmosphere, the carbon cycle, basic atmospheric chemistry, atmospheric carbon dioxide, and greenhouse gases, radiative forcing, physical climate processes and feedbacks, and regional climate issues. We will briefly consider the links between the atmosphere and the Critical Zone throughout the lesson.
As you read through the assigned material, you should always make note of and consider the potential link between the subject matter and the Critical Zone. For example, what effect does atmospheric chemistry have on the Critical Zone and how are they linked? We will return to considering these links in more detail later in this lesson and in Lesson 12.
Much of our understanding of the atmosphere and climate system derives from the recent focus on the impact of human society on the greenhouse gas content of the atmosphere and global climate change. The Intergovernmental Panel on Climate Change (IPCC) [49] (go there and read "About IPCC") is a scientific panel established by two organizations of the United Nations in 1988 to evaluate the risk of climate change from human activity. The main activity of the panel is to publish special reports based on assessments of peer-reviewed and published scientific literature—four reports have been published in three volumes each, the most recent in 2007. Much of the background information and reading for Lesson 2 was culled from the 3rd and 4th assessment reports.
In 2007, the IPCC received a Nobel Peace Prize for its work. Among the 2,000 contributors (including Al Gore), there were five Penn State faculty who shared in the prize: Michael Mann, Richard Alley, Bill Easterling, Klaus Keller, and Anne Thompson were all substantial contributors to the Intergovernmental Panel on Climate Change.
Lesson 3 will take us one week to complete. As you work your way through these online materials for Lesson 3, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 3. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMITTED FOR GRADING? |
---|---|---|
"Calculating Carbon Footprints" | page 6 | Post to the Lesson 3 - Carbon Footprint discussion forum, then discuss. |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
The field of climate dynamics studies the processes that control the climate system and how it evolves. The climate system is controlled by the interaction of the atmosphere, the oceans, [50] the land surfaces, the cryosphere, and the biosphere, averaged over time-scales of weeks to centuries and millennia. Climate can be classified [51] into spatial zones based on, for example, regional similarities in temperature and precipitation—these zones [52] often contain similar biotic elements from region to region.
The primary energy that drives Earth's climate system and sustains life is solar heat [53] and light. The amount of solar energy that reaches Earth’s surface varies because of latitudinal position on the planet, internal solar processes, changes in Earth's orbit, Earth's albedo [54], changes on Earth such as major volcanic eruptions of dust that block the incoming solar energy, or changes in atmospheric composition. Earth's energy balance is complex. About 30% of incoming solar energy is reflected back to space, with 70% being absorbed by the atmosphere and surface of the planet.
To get a better overview of the climate system, there are three reading assignments I would like you to complete before we proceed. Once you have completed these three reading assignments, continue with this online lesson.
In succeeding portions of this lesson, you will explore some of the topics described in the chapter in more detail, but it is the generalized overview of the material presented in the chapter that I am most interested in seeing you master. On the first page of the chapter you will find a definition of the climate system as "an interactive system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the land surface and the biosphere, forced or influenced by various external forcing mechanisms, the most important of which is the Sun." Confusingly, this sounds a lot like descriptions of the Critical Zone we read in Lesson 1! Remember: While the Critical Zone consists of portions of these "spheres," the central component of the Critical Zone is soil, the consequence of complex processes operating at the interface between the "spheres."
(Optional) Read Chapter 10 (pp. 419–460) in
This chapter is available through Library Reserves. Do not focus on the details of this chapter and do not worry about references to earlier chapters, figures, etc. Your primary goal should be a very generalized understanding of the climate system, always considering in the back of your mind what implications this information may have to the Critical Zone.
Check out these Climate Education Modules [60] for teachers. The website was created and is hosted by North Carolina State University, and pays particular attention to the southeast of the U.S. However, the website provides links to relevant National Science Education Standards and many pages include classroom activities.
The biogeochemical cycle in which carbon is exchanged between Earth’s terrestrial biosphere, hydrosphere, geosphere, and atmosphere is called the carbon cycle. The global carbon budget is the balance of the fluxes of carbon between these four reservoirs. The terms source or sink define whether the net carbon flux is out of or into the reservoir, respectively.
The carbon cycle is of interest to understanding climate because it includes two of the most important greenhouse gases: carbon dioxide (CO2) and methane (CH4). Most atmospheric carbon is in the form of CO2, while CH4 is present only in trace concentrations. Because CO2 is chemically inert, it is relatively well mixed within the atmosphere away from forest canopies, whereas CH4 is chemically active and is removed quickly from the atmosphere through oxidation to CO2 and water. The overall atmospheric concentration of these greenhouse gases has increased during the past century and contributed to global warming.
Carbon is removed from the atmosphere through:
Carbon can be input to the atmosphere by a variety of processes, including:
Inorganic carbon is readily exchanged between the atmosphere and ocean, exerting an important control on the pH of ocean water. Carbon is released to the atmosphere at oceanic upwelling sites, whereas regions of downwelling transfer carbon from the atmosphere to the ocean. When carbon (CO2) enters the ocean, carbonic acid is formed by the reaction: CO2 + H2O = H2CO3. Carbonic acid dissociates to form bicarbonate ions (HCO3-), the form in which most of the carbon in the oceans exists; lesser amounts of carbon exist as carbonic acid (H2CO3 or dissolved CO2), and carbonate ions (CO32-) paired with calcium and magnesium and other cations. Marine organisms build their skeletons and shells out of the minerals calcite and aragonite (CaCO3) through the incorporation of bicarbonate ions. These minerals dissolve after the death of the organism, but some of the material settles to the sea floor where it can be buried and stored in the form of limestone.
Carbon is an essential part of life on Earth. It plays an important role in the structure, biochemistry, and nutrition of all living cells. Autotrophs are organisms that produce their own organic compounds using carbon dioxide from the air or water they live in. This lifestyle requires an external source of energy, for example, the absorption of solar radiation in the process called photosynthesis, or the exploitation of chemical energy sources in a process called chemosynthesis. The most important autotrophs for the carbon cycle are trees in forests and phytoplankton in the ocean.
Large quantities of carbon pass between the atmosphere and biosphere on short time-scales: the removal of atmospheric carbon occurs during photosynthesis, following the reaction CO2 + H2O = CH2O + O2, while most carbon leaves the biosphere through respiration, a reversal of the previous reaction in which an amount of energy equivalent to that absorbed during photosynthesis is released as heat. When oxygen is present, aerobic respiration occurs, which releases carbon dioxide into the surrounding air or water. Otherwise, anaerobic respiration occurs and releases methane into the surrounding environment, which eventually makes its way into the atmosphere or hydrosphere.
The biosphere is capable of storing ~10% of atmospheric carbon at any given time. However, carbon storage in the biosphere is influenced by a number of processes on different time-scales: while net primary productivity [62] follows seasonal and annual cycles, carbon can be stored up to several hundreds of years in trees and up to thousands of years in soils. Changes in those long-term carbon pools may thus affect global climate change (view this example of changes to soil) [63].
Organic and inorganic carbon reservoirs in Earth's crust are large with long residence times. Carbon enters the geosphere through the biosphere when dead organic matter (such as peat or marine algae) becomes incorporated into fossil fuels like coal and organic-matter-rich oil and gas source rocks, and when shells of calcium carbonate become limestone through the process of sedimentation briefly described above. These carbon reservoirs can remain intact, that is, the carbon can remain stored within them, for many millions of years. Eventually, most rocks are uplifted and subjected to exposure to the atmosphere where they are weathered and eroded, or they are subducted, metamorphosed, and erupted through volcanoes, returning the stored carbon back into the atmosphere, ocean, and biosphere. Our society's dependence on fossil fuels bypasses this natural process by moving as much carbon from the geosphere to the atmosphere in a single year as what might otherwise require hundreds of thousands or millions of years. In Pennsylvania, when we strip mine and burn coal we are in effect releasing the atmospheric carbon dioxide and stored energy of the sun that has been buried for over 300,000,000 years!
On a trip to Bear Meadows, near the University Park campus of Penn State, I describe atmospheric carbon and organic carbon storage in the Critical Zone.
Next, visit a Pennsylvania coal seam and nearby electric generating station to learn about the relationship between Bear Meadows and the burning of coal.
Earth's surface temperature and climate are controlled by the amount of radiation received from the Sun: when incoming radiation is greater than outgoing radiation the Earth is warmed, and vice versa. Changes in the balance between incoming and outgoing radiation are referred to as radiative forcing. While the intensity or energy output from the Sun varies through time, other Earth-bound processes affect radiative forcing. For example, the gaseous and particulate composition of Earth's atmosphere plays an important role in controlling the energy balance. Changes in the natural landscape and human land-use also influence radiative forcing.
Three processes have contributed to human-induced increases in the carbon dioxide content of Earth’s atmosphere. Two of these processes concern emissions: increasing global economic activity and an increase in the use of fossil fuels to drive the economy. The third process is a suggested decline in the efficiency of CO2 sinks on land and oceans in absorbing human emissions. These changes characterize a carbon cycle that is forcing stronger-than-expected and sooner-than-expected climate change.
The United States ranks first in total and per capita emissions among the top twenty carbon dioxide-emitting nations and is responsible for more than 22% of the total annual carbon dioxide introduced to the atmosphere by human activity. For perspective, the United States population stands at ~4.5% of the total global population—our society’s profligate lifestyle is supported by our consumption of a greater proportion of Earth’s resources than the rest of humanity and therefore translates to a greater share of the waste products of human activities, in this case, human inputs of carbon dioxide to the atmosphere.
Although the United States Federal government has a policy regarding greenhouse gas emissions and climate change (see U.S. Climate Policy and Actions [67]), each citizen, church, school, and business—all of us—can play a role in reducing our nation’s carbon dioxide input to the atmosphere. Reducing the amount of energy we use is one important step in the effort to reduce carbon dioxide emissions. To do so, we must first inventory our carbon dioxide emissions by identifying the energy-intensive activities we partake in throughout our day-to-day lives.
Go here to find information that was once available through the link above: January 19, 2018 Snapshot [68].
You may also be interested in exploring the U.S. Climate Resilience Toolkit [69], designed to help citizens, communities, businesses, and others to manage climate-related risks and to improve resilience to extreme events.
For this activity, you are to use three different "calculators" to calculate your own carbon footprint. As you use the three calculators, consider these questions:
I ask you to be honest, with yourselves, with me, and with your classmates. Remember: On average, the U.S. citizenry’s carbon dioxide emissions are grossly out of balance with the rest of Earth’s human inhabitants, so we all play a role in current emission levels. Let’s see what we can learn through a non-judgmental assessment of our community’s lifestyles.
You will be graded on the quality of your participation. See the grading rubric [47] for specifics on how this assignment will be graded.
Interested in determining the potential C footprint for a planned building construction or retrofit? See: the Green Footstep website [72] to learn how to plan and design for C neutrality.
Also, visit Global Footprint Network [73] for yet another C footprint calculator as well as an assessment of various country's standing with respect to their C emissions and more.
Earth's atmospheric processes and climate may be the most influential factors involved in soil formation in the Critical Zone because processes like precipitation and temperature control weathering over large geographic regions. Once we grasp their importance we begin to properly understand the varying effects of climate on the Critical Zone. In this lesson, you read a lot of material describing these processes, learned about the Intergovernmental Panel on Climate Change (IPCC), performed a carbon footprint calculation, and applied knowledge gained during the calculation to consider Critical Zone-relevant issues of personal and societal behavior.
By now you should feel comfortable describing: components of the climate system and the basic natural and anthropogenic forces that affect the climate system; the carbon cycle and fundamental atmospheric chemistry; and radiative forcing of climate change. In the next lesson you will apply this knowledge to understanding paleoclimates (ancient climates), and from there determine how our knowledge of paleoclimates helps us to understand ongoing and future climate change.
You have reached the end of Lesson 3! Double-check the list of requirements on the Lesson 3 Overview page to make sure you have completed all of the activities listed there.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
We will now turn our attention toward the evolution of Earth's atmosphere and ocean system through geologic time, specifically focusing on our understanding of paleoclimatology (ancient climates). We will consider potential lessons from this knowledge of ancient climate under so-called greenhouse and icehouse conditions. In particular, I will ask you to consider how this knowledge can aid our predictions of, and planning for, future climate change.
Lesson 4 will take us one week to complete. As you work your way through these online materials for Lesson 3, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 4. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Short (2–3 page) paper on "Exploring the links between paleoclimatology, the Critical Zone, and modern society" | page 4 | Post to the Lesson 4 - Paleoclimatology Activity dropbox in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
Paleoclimatology, the study of ancient climates, has become increasingly recognized as a socially relevant tool for unraveling the causes and consequences of ongoing and future climate change. Scientists use the knowledge and insight gained from reconstructing ancient episodes of climate change to better understand how Earth's future climate may behave during climate states not experienced during recorded human history. In addition, a complete understanding of natural climate variability allows us to better identify and understand the role of human activity on climate change. For example, we know that ancient episodes of warmth have occurred in which crocodile-like reptiles and subtropical forests thrived throughout the high arctic. During these times, the atmospheric hydrologic cycle was amplified, the quantity of precipitation was elevated and more broadly distributed, and weathering and soil formation were intensified with tropical soil-forming conditions extending into the mid- to high-latitude regions of the planet.
Tim and colleagues are working to reconstruct one such interval in Earth history the Paleocene-Eocene Thermal Maximum.
To begin to understand the ties between this work and the carbon cycle, view this video from Svalbard.
(Where is Svalbard? [75])
The record of paleoclimate variation in Pennsylvania includes very ancient paleosols formed during episodes of tropical climate conditions to the more recent deposits of vast ice sheets that extended far to the north into Canada. To learn more view the following video.
Before we delve into the specifics of paleoclimatology, I want you to understand current views on the evolution of Earth's atmosphere and ocean system. Much of this information is highly theoretical, based on scant geologic evidence from the very distant past and computer models. However, this information will provide you with a baseline comprehension of natural variations in Earth's climate, for comparison to human-induced (or anthropogenic) causes of climate change.
I also want you to understand how politics can influence science. Some of the links below, specifically those from the US Environmental Protection Agency for Past and Recent Climate Change, are archived and not easily available - this is a function of a different attitude toward climate change research from our current president and his admininstration. Thus, I have provided other links to similar material though I encourage you to explore the EPA links anyway.
In this assignment, you will begin to explore the links between paleoclimatology, the Critical Zone, and modern society.
Next, carefully study the map below, then learn more about laterites [88]. Mid-Cretaceous refers to a broad expanse of geologic time from ~120,000,000 to 85,000,000 years ago, when the planet was generally much warmer than today with, for example, dinosaurs stomping around in sub-tropical forests near both poles. As you read about laterites you may want to refer back to knowledge gained in our lesson on soils and soil orders, specifically the geographic distribution of oxisols.
L4_paleoclimatology_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L4_paleoclimatology _eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your paper to the "Lesson 4 - Paleoclimatology Activity" dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Those of us fortunate enough to have experienced Earth sciences in primary and secondary school probably learned about gradual climate change through geologic time, such as the gradual waxing and waning of continental-scale ice sheets during the last ice age. This view of paleoclimate change is appropriate in the context of Earth history and geologic time. However, more recently, paleoclimatologists have gathered evidence for widespread abrupt changes in climate that occurred in the not-too-distant past, on time-scales equivalent to a human lifetime. For those who are attentive to these issues, this realization has served as a "wake-up call" to action—humanity's effect on atmospheric composition and climate change may push the climate system toward a "tipping point" from which rapid regional and global changes in climate of unknown magnitude and duration may occur. The question remains whether human action to reduce greenhouse gas emissions can avert such events.
Read the following text chapter:
The first few pages of the chapter provide a brief overview of paleoclimate proxy interpretations, information you should now be familiar with and therefore can skip here if you choose. Pay particular attention to the discussion of the Younger Dryas, the most recent widespread episode of abrupt climate change for which abundant, globally distributed terrestrial and marine data has been collected.
The concepts and terminology through this portion of the chapter should mostly be familiar to you.
When you reach the sections entitled "Patterns of Climate Variability" and "Trends Recorded Instrumentally," you may find that the terminology is unfamiliar—do not fret. Your primary focus through this portion of the chapter should be to understand that human records of recent-past climate change do exist and provide evidence for and are relevant to our understanding of ongoing and future climate change. Also, read the final section entitled "Synopsis of Observations."
To properly understand and plan for the potential range of variability in Earth's future climate and its effects on the Critical Zone, we must look to the ancient past to understand that Earth's climate has experienced extremes in climate, cold and warm, outside of the span of human history. You just read a lot about paleoclimatology, learned about various government agencies that are interested in paleoclimatology, and viewed maps of glacial and extremely warm greenhouse deposits of the past to consider what socially relevant information might be gleaned from those distributions.
As you shift your attention toward Lesson 5, you should feel comfortable describing: basic concepts of paleoclimatology and the type of information that can be collected to reconstruct ancient climates; Federal agencies with ongoing research in paleoclimatology; examples of paleoclimatologic information that may be relevant to your life and society; and issues regarding the rate of climate change and what we know about the potential abruptness of climate change. In Lesson 5, we will complete Unit 3 by studying regional climate change and taking a more focused look at links between atmospheric processes and the Critical Zone.
You have reached the end of Lesson 4! Double-check the list of requirements on the Lesson 4 Overview page to make sure you have completed all of the activities listed there.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
The atmosphere is a complex portion of the Earth system that greatly influences Critical Zone processes. It should be clear to you now that a wide range of climate states have existed in Earth history that fall outside of the realm of human experience. Further, you now know that these climates of the past—paleoclimates—provide us with great insight into present-day atmospheric processes and that paleoclimatic variations led to changes in Critical Zone processes of the past.
In Lessons 3 and 4, you studied modern and ancient atmospheric processes at a planetary scale. In Lesson 5 you will further explore predictive modeling of future climate change and what our best scientists and computer models predict will happen to atmospheric carbon dioxide levels, temperature and precipitation, storms, and sea level in Earth's not-too-distant future
To better understand some of the very basic general concepts of climate modeling, I will take advantage of the nearby presence of my colleague Dave Pollard, an internationally known paleoclimate modeler and co-author of the GENESIS global climate model (GCM). Dave's depth and breadth of knowledge of computer codes, GCMs and paleoclimate will be obvious as you watch the series of videos we created and will help you to better understand and digest the readings I have assigned in this lesson.
See Transcript: Meet Dave Pollard
TIM WHITE: Hello. Welcome to my office. Perhaps now when you're communicating with me you can imagine this is where I operate from. But we're really here today because a colleague and neighbor of mine, Dave Pollard, is a paleoclimatologic modeler, and so we're going to go over to Dave's office and have a little conversation with him.
Hey Dave.
DAVID POLLARD: Hi, Tim.
TIM: How you doing?
DAVID: Fine.
TIM: You have a couple minutes to have a chat?
DAVID: Sure. Come on in.
TIM: Thanks. So when did you start climate modeling?
DAVID: I first started the simple climate modeling in grad school. I did a simple couple glacier ice sheet model of the Pleistocene ice ages. And that's when it started.
TIM: And then your post doc?
DAVID: I did a post doc in Oregon State, and I worked on-- for the first time there-- on global climate models. The big, complex, global models that Larry Gates used then. Applied to the quaternary ice ages. I later worked for NCAR, which is in Boulder, Colorado. It stands for the National Center for Atmospheric Research. They do a lot of different things there. The division I worked in was called climate and global dynamics, which mainly developed community climate global climate model that people use a lot in the United States and internationally for paleoclimate and modern and future climate modeling.
TIM: And I suppose it was at that time you created or coded Genesis?
DAVID: While I was there, my group decided to develop a global climate model specifically aimed at the paleoclimate modeling community, and so we built GCM, which stands for Global Climate Model, or General Circulation Model, and we called it Genesis. And that was in the 1980s and 1990s, and quite a lot of paleoclimate modelers used it at that time. In the late 1990s, I moved to Penn State. There was a dynamic group here led by Eric Baron at the time doing a lot of paleoclimate modeling work, and I joined that. And since then, I've worked here on Genesis climate model and also a lot on ice sheet modeling, which maybe we'll talk about a little later.
See Transcript: Modeling Climates
TIM WHITE: You've used the term climate modeling quite a bit in describing yourself, so maybe this is a good time to tell us-- from your perspective, what is climate modeling?
DAVID POLLARD, Sr. Research Associate, Earth and Environmental Systems Institute: Well, climate modeling, and in particular global climate models, are really large computer codes. They're quite like the codes that are used for weather forecasting by the National Weather Services. But they're simplified a little bit so that they can be run instead of over a few days where you're interested in really getting the weather right tomorrow in the next four or five days so that you can run them over 10 years if you like or 100 years to get a projection of the average climate. They still have all the storms and the weather events in them simplified a little bit so they're efficient enough to run for those long-time scales.
And the other thing that's different about them is that they have a lot of other components. They're coupled to other things that interact with the weather over that time scale like snow. The thickness of snow, the temperature and amount of moisture in the soil, oceans, the effect of vegetation. That sort of thing.
How Do Climate Models Work?
Some things you have to just prescribe from observations, but then a lot of it is in the physics of the equations themselves. The things you prescribe are the amounts of sunlight coming in at the top of the atmosphere, which is determined from the current orbit the seasonal cycle of the Earth around the sun. The amount of carbon dioxide and other gases in the atmosphere. The types of vegetation that distributed around the globe.
That sort of thing. And then, when you run the model, just about everything else that you can think of to do with the weather is predicted from the equations. Air speeds, temperatures, humidities, they're all in the physics.
Climate Models and Soil
TIM: Do soils play a role in the models?
DAVID: Yes. For global climate modeling, you generally have a model of the top few meters of soil, which includes most of the critical zone. Not ground water, but the upper soil layers, which includes the seasonal cycle of temperature going down to about a meter. And what these models predict in the physics is the soil temperature and the soil moisture. The amounts of water in the pores.
TIM: And what about surface water like lakes or rivers? Are they in the model?
DAVID: Usually not explicitly. You don't predict river flow, for instance. You're not going to get the speed of the Mississippi current, but what is predicted is the local runoff averaged over soil areas. And then what you can do from that is deduce the average river output integrated over the whole Mississippi basin, for instance. And lakes are just prescribed, usually.
TIM: What about ice?
DAVID: Well, there's the seasonal snow pack coming and going, how it melts in the spring and then forms in the fall and winter, is predicted from the amounts of snowfall falling from the atmosphere. And sea ice is also predicted, which is of interest recently, because of the rapidly receding cover in the Arctic, for instance. That's included in these climate models when they apply it to the future.
But the big ice sheets, like Greenland and Antarctica today, they're prescribed. Those time scales of the variations of thousands to tens of thousands of years and these global climate models can only be run realistically, with computer power that we have for decades or a few hundred years at most at a time. So you have to prescribe these long-term features like ice sheets.
Computer Power & Coupled Modelling
Coupled modeling, which I do quite a bit, where you use tricks, really, to run these global climate models only for a few decades and then couple them to separate models of the ice sheets where you can try and then run just the ice sheet model over thousands, ten thousands, or even millions of years to predict their variations in the past.
See Transcript: Modelling Modern & Ancient Climates
TIM WHITE: You've told us a lot about climate modeling in general, and you've alluded to some of your work in paleoclimate modeling. And I wondered if you could perhaps tell us a little bit more about some of the differences between modeling ancient climates and modern climate.
DAVE POLLARD, Sr. Research Associate, Earth and Environmental Systems Institute: Sure. You actually use the same physical model, which is a good thing. You want to use exactly the same physics in the model, be it just the general circulation model, as works for the present. And just shift that and apply that to the past. But to do that, the main thing you have to do is to change the boundary conditions.
Then that means the layouts of the components as they varied very much, if you go far back, due to plate tectonics. The amounts of carbon dioxide in the atmosphere, which could be four times, eight times, or more if you go back to the Cretaceous, say, 100 million years ago. Then if you're interested in orbits, and Milankovitch orbital perturbations over the ice ages, for instance, you set different orbital parameters. The eccentricity, the precession, and obliquity of the Earth around the Sun.
So there's a handful of those things, about four or five changes to the external boundary conditions, that you impose on the GCM. And then you simply run it, just like you would for the present, except you're simulating the climate 100 million years ago, say.
How are Ancient Climate Models Relevant Today?
So do these paleoclimate simulations have any relevance to the future and to society's concerns? And I think the answer's definitely yes. We're about to enter, in the next few centuries to millennia, unprecedented increases in greenhouse gases, which are going to warm the climate tremendously.
Now, we can attempt to just model that with models based on the present day, but if we can go back in the past to when greenhouse gases were the same levels as we anticipate, two to three to four times what they are today, that gives us an analogy. And just a means of testing the models to see if they're doing the right job for the past. And then we'll have more confidence for them in the future.
For instance, the last time that greenhouse gases were three to four times present-day amounts was in the-- before about 40 million years ago. 100 million to 40 million years ago. And we can simulate those conditions and compare with paleoclimate data that we have for those periods and see if the models are doing a reasonable job.
Another example concerns parts of the present-day ice sheets, for instance, West Antarctica and also Greenland. And it's quite hard to model those. But we've coupled ice sheet and climate models to see if they are vulnerable if they're in danger of totally disintegrating, for instance, in the case of West Antarctica, in the next 1,000 years due to increases in ocean and air temperatures caused by humans. But we can look in the past to see if those parts of the ice sheets have collapsed or not. And when they have, what were the climates that caused that, and try to simulate those with our coupled models.
Another great thing about these models is helping to communicate to the public what's really going to happen. The three-dimensionality of them means that you can make nice graphics and animation, and also run them forward in time to produce movies. And that sort of visual has a big impact and potency for the public to really see what might happen.
For instance, we can run these ice sheet models and watch the ice sheets coming and going over tens of thousands of years and through ice age cycles. And also how they might recede in the future. And so that's a great way of communicating to the public much better than dry tables and thousands of just figures that you might think.
TIM: Well, this is great. Let's have a look at some examples of your work.
DAVE: OK.
Modeling the Ice Sheets
This shows work I've done coupling global climate models with ice sheet models. And this particular experiment was aimed at the last glacial maximum, 21,000 years ago-- really recently, geologic time, when ice sheets covered a lot of the known hemispheric continents, almost all of Canada, with kilometers thick ice sheets. And it's a real mystery why they came and why they went away again over very short geologic time periods.
And the purpose of this experiment was just to see if the global climate model could produce reasonable snowfall and snow melt patterns over these ice sheets. And that's what you need to do if you think about the long term evolution of them, because what is the net annual input of mass onto the surface versus the melt? That controls whether they recede or advance. So I use the global climate model with these boundary conditions to produce maps of snowfall, snow melt, and the net balance.
TIM: We've actually discussed this episode in the class. And during this time, part of Pennsylvania was covered with ice. But I'm curious, were you able to adequately model the ice sheet?
DAVE: Yes. These amounts of snowfall and snow melt are quite reasonable from what we can deduce about what they should be at the last glacial maximum, which is actually since the ice sheets were at their maximum, they weren't rapidly receding or growing. The net input of mass should be close to zero. And that's how it works out in these simulations.
But the atmosphere and climate system are more complex than we've considered thus far. Perhaps you gained some insight into this concept when considering the ancient climate-relevant deposits and the relationship between greenhouse paleosol and modern oxisol distributions. Therefore, we will consider, in more detail, the differences in climate between regions, specifically looking at predictions of regional climate change in the United States. You will think and write about how these predictions may affect the Critical Zone within a region.
Finally, we will close Lesson 5, and Unit 3, with some readings that link Earth's atmosphere to soil and provide predictions of changes in soil that we may expect as a result of climate change.
What is due for Lesson 5?
Lesson 5 will take us one week to complete. As you work your way through these online materials for Lesson 5, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 5. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Discussions on regional climate issues | page 3 | Participate in the Lesson 5 - Regional Climate team and class discussion forums in Canvas |
Short (2-page) paper on links to the Critical Zone | page 4 | Post to the Lesson 5 - Links to the Critical Zone dropbox in Canvas |
Discussion - Teaching and Learning About Atmosphere and Climate | page 5 | Participate in the Unit 3 - Teaching and Learning About Atmosphere and Climate discussion forum in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
Future climate change projections are based on our understanding of the atmosphere, ocean, and climate system as it is mathematically represented in powerful computer models of the globe that reconstruct physical and chemical processes. These models are tested by their ability to accurately represent modern climate conditions and by using paleoclimate proxy data to "ground truth" model output for past climate conditions. In this manner, scientists can determine whether or not models accurately reconstruct the full range of climate extremes that can occur in Earth's climate system.
Many models have been applied to determine Earth's near-future climate. The results of these modeling efforts can then be applied to anticipating changes in Critical Zone processes, many of which are extremely relevant to the health of human society and all life on our planet.
To learn more about future climate change predictions, please read the "Future Climate Change [90]" section of the United States EPA Web site (but instead go here [91]).
Also, visit the Climate Inspector [92] page in the U.S. Climate Resilience Toolkit to view future climate simulations from one of the leading global climate models.
(Optional) Read Chapter 11, Near-term Climate Change: Projections and Predictability [93], in Climate Change 2013: The Physical Science Basis, IPCC.
Struggling to teach climate change in your 9-12 classroom?
Check out: Visualizing and Understanding the Science of Climate Change [94]
To learn more about regional climate issues, complete the following learning activity.
See our course calendar in Canvas for specific activity due dates.
You don't have to read the entire reports . . . we are going to do this part of the activity in five (5) teams. Team membership will be provided by the start of this lesson week.
Here is how each team should proceed with the readings:
Upon completion of the reading, you are to engage in a discussion of the readings, first within your team and then with the rest of the class. The team discussion component of this activity will take place over two days and will require you to participate multiple times over that period. Likewise, the class discussion will then take place over the subsequent two days. See our course calendar in Canvas for specific dates.
Once you have discussed these topics within your team, we will regroup to engage in a discussion with the entire class. This class discussion will take place in a separate discussion forum in Canvas titled "Lesson 5 - Regional Climate: Class Discussion."
You will be graded on the quality of your participation. See the grading rubric [100] for specifics on how this assignment will be graded.
As we progress through the semester, you will learn that all of the various "spheres" that overlap in the Critical Zone, and all of the state factors of soil formation, are complexly interrelated—it is difficult to tease out the effects of a single factor or "sphere," on the Critical Zone. Nonetheless, it is worthwhile to assess aspects of Critical Zone science associated with a single "sphere," if for no other reason than we can draw on the accumulated knowledge of various scientific sub-disciplines that have focused on an individual "sphere." More importantly, though, is the fact that my brain best understands and learns simple concepts, so we will more closely consider the effects of a single variable, the atmosphere, on the Critical Zone to complete this lesson.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L5_links_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L5_links_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Submit your work to the Lesson 5 - Links to the Critical Zone dropbox in Canvas by the due date indicated on our Canvas calendar. (See the Modules tab in Canvas)
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Let's take some time to reflect on what we've covered in this unit!
For this activity, I want you to consider how you might adapt the materials of this unit to your own classroom. Since this is a discussion activity, you will need to enter the discussion forum more than once in order to read and respond to others' postings.
You will be graded on the quality of your participation. See the grading rubric [47] for specifics on how this assignment will be graded.
This has been a long unit with a lot of reading and writing. By now though you should have a strong basic understanding of atmospheric processes and the full range of climate change that can occur on Earth, on both the global and regional level. You should also understand the overwhelming scientific information indicating that climate change is being driven by anthropogenic causes, that this change is occurring very rapidly, and that the change will affect the Critical Zone and soil resources. All is not lost however—the scientific community has begun to discuss various management strategies to deal with potential degradation of the Critical Zone. Whether you realize it nor not, you can apply this newfound knowledge to modify your own behaviors and help to develop strategies that will allow society to survive and perhaps thrive under warmer Earth conditions—perhaps your students will learn from you and do the same.
In the next unit we will focus on the hydrologic cycle, and surface and ground water resources, which are all intimately tied to the atmospheric processes you have just studied and mastered.
You have finished Lesson 5. Double-check the list of requirements on the Lesson 5 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
Agua es vida (Water is life [102])—that statement adorned the logo of a water-well-drilling company I worked with many years ago in Puerto Rico, and to me, the phrase highlights the importance of water on Earth. Remember that 78% of a human baby's body is composed of water, as is 55–60% of an adult's body; obviously, water is a truly critical component of sustaining life on Earth.
Water covers ~70% of Earth's surface. Most of this is in the oceans, a realm of Earth not covered in this course. However, the global ocean is more than peripheral to the Critical Zone. Ultimately, all of the water that bathes the Critical Zone was evaporated from the ocean surface, transferred to the continents as vapor via the atmosphere, and deposited on the land surface as liquid or solid precipitation, depending on regional climate. In this unit, we will learn about water's role in the Critical Zone. We will accomplish this in Lesson 6 by first considering in some detail the so-called water cycle. Because of the role of the atmosphere, we will revisit some aspects of atmospheric processes. This should serve to demonstrate the intimate link between the various "spheres" (our last unit with this one) that overlap in the Critical Zone!
The water cycle involves much more than the transfer of water from the ocean to the land surface. Once precipitated, water can flow across the land surface, infiltrate into the subsurface as soil pore water or groundwater (remember that the base of the Critical Zone is defined as the depth to which groundwater freely circulates), or be evaporated or transpired by plants (the top of the Critical Zone!) back to the atmosphere. In this lesson, we will consider the many processes involved in the flow of water through the Critical Zone.
Water is known as the universal solvent—rarely is it found in a pure state because many substances will readily dissolve in it. Thus, we will include brief considerations of water chemistry and quality (we will return to this topic again when considering landforms and biota) and the role human society has played in degrading this invaluable resource. In our landform unit, you will also learn about the role water plays in transforming and sculpting the land surface, while in the biota unit we will explore the many interactions between water and life in the Critical Zone, thus further linking the Critical Zone "spheres."
Finally, because of the somewhat mysterious nature (out of sight, out of mind) of groundwater, you will study various aspects of groundwater flow in Lesson 7, and complete the water unit by reading about links between water and Critical Zone science. Enjoy.
In an earlier lesson, I described soil as the "heart" of the Critical Zone. With that analogy in mind, perhaps you can consider water to be the “blood” of the Critical Zone. Once precipitated onto a landscape, water can be stored at the surface in various reservoirs depending on the climate of a region, flow across the surface, or infiltrate into and flow through the subsurface domain. Along the various pathways, water can transfer dissolved constituents from one portion of the Critical Zone to another. Those constituents may degrade water quality, precipitate minerals, or provide sustenance for life, among many other processes. As in earlier lessons, you should not be concerned with memorizing and repeating various definitions for the many processes you will read about and study. Instead, begin by securely grasping the concept of the water cycle. Once you have mastered the water cycle, move on to learn about the chemistry of natural waters and human influences on water in the Critical Zone.
What will we learn about in Lesson 6?
By the end of this lesson you should be able to:
Lesson 6 will take us one week to complete As you work your way through these online materials for Lesson 6, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 6. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Report on StreamStats | page 6 | Post to the Lesson 6 - StreamStats dropbox in Canvas dropbox |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
The term "water cycle" does not refer to water craft you can peddle across water—instead the water cycle describes the transit of water through all of the components or "spheres" of the Critical Zone (atmosphere, hydrosphere, lithosphere, biosphere, and soil) and the processes involved in that transit.
The chemistry of natural water, aqueous chemistry (or aqueous geochemistry), is a complex subject well beyond the reach of this course. However, some very basic concepts of water chemistry are important to help understand the role of water in the Critical Zone.
Humanity's use of water has a long history for obvious reasons—agua es vida! Civilization is thought to have first arisen in the Tigris-Euphrates River Valley, where irrigation canals have been used for at least 6,000 years. In addition, the site of vast water bodies (lakes, oceans) or flowing water in rivers and streams, provide aesthetic appeal and comfort for many, as well as providing sources for food, waste disposal, and recreation. For these reasons among others, humans have lived and worked near water, exerting strong and important influences on the water cycle, water quantity, and quality.
USGS has placed much of its surface water gauging data online using a Web-based tool called Streamstats. In this exercise, you will learn to use Streamstats to gather information about a study site. Ideally, this study site will be the same as the soil site you identified in Lesson 2. However, you will see that not all of the states have fully implemented this tool, so if you are from a state other than Pennsylvania and chose a soil site in that state, you may not be able to use Streamstats to evaluate your soil site. Read on.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L6_surfacewaterstudies_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L6_surfacewaterstudies_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your report to the "Lesson 6 - Surface Water Studies Activity" dropbox in Canvas (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
The importance of water in the Critical Zone cannot be overstated. Water plays a primary role in physical and chemical weathering, erosion and transportation of sediments and dissolved ions, and the sustenance of life, to name a few processes. You should understand the water cycle and the various reservoirs in which water is stored and transported through the Critical Zone. You should also understand basic concepts linking water flow to the natural chemistry of water, and human influences on water resources. Finally, you should be confident in your ability to access widely available river and stream gauge data and should have used this data to learn about the surface water characteristics of your study site.
Here are some links to some Teacher's Domain resources (developed by Penn State!) that you might even want to use in your own classrooms:
You have finished Lesson 6. Double-check the list of requirements on the Lesson 6 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
So far you've learned that the water cycle includes the infiltration and flow of water into and through the subsurface. Many citizens are familiar with groundwater, since approximately one-third of us obtain our drinking water supply from groundwater. People discuss "aquifers," underground lakes, and the mythical existence of a deep underground connection between Loch Ness (Scotland) and Lake Champlain (Vermont) that explains reports of large ancient dinosaur-like creatures in both places. However, groundwater is no mystery! The presence and flow of groundwater are governed by the same physical processes that operate within our view on Earth's surface.
In this lesson, we will spend some extra time considering the water that exists beneath our feet. First, you will read about and consider soil moisture in the unsaturated zone, and then progress to read about and study groundwater. You will access, use, and interpret online groundwater data very similar to what you accomplished in your surface-water study in the last lesson. Finally, we will close by thinking in more depth about the links between water, the water cycle, and the Critical Zone!
By the end of this lesson you should be able to:
Lesson 7 will take us one week to complete. As you work your way through these online materials for Lesson 7, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 7. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Report (6–7 pages) on groundwater studies | page 4 | Post to the Lesson 7 - Groundwater Activity dropbox in Canvas |
Discussion—Teaching and Learning About Water | page 6 | Participate in the Unit 4 - Teaching and Learning About Water discussion forum in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
In most places, an unsaturated zone of soil, sediment, and bedrock exist close to Earth's surface. Although it is unsaturated, the zone still may contain water by capillary action and adhesion to soil particles. This so-called vadose zone exists from the soil surface beneath our feet to the top of the water table. This should be relatively easy to understand if you imagine that if all of the soil and sediment beneath us was saturated, we'd constantly be walking through mud, quicksand, etc., dependent upon the parent material. Instead, as water infiltrates into the subsurface, much of it flows to the water table, while some is retained in the soil and sediment column, the vadose zone.
Remember that this unit on water and lesson on groundwater present only a broad overview of some very complex topics. Here you will have an opportunity to revisit and expand your knowledge of some of the topics covered in part 2 of this lesson—I consider the concepts presented here to be important for understanding links between surface and groundwater. To me, these concepts highlight the complex interplay of surface and subsurface processes that are active in and affect the Critical Zone.
Review the following information and resources:
You can learn more about groundwater at USGS [128]. More importantly, you can access a number of resources, including posters for your classroom, at this site. I highly recommend spending time here.
A detailed map of Earth's groundwater resources can be viewed and downloaded at WHYMAP [129].
USGS has placed much of its groundwater database online. In this exercise, you will learn to access this data to gather information relevant to your soil and surface water study site.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L7_groundwater_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L7_groundwater_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your report to the "Lesson 7 - Groundwater Activity" dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
If you have not concluded that the Critical Zone is a complex maze of processes and interactions, you soon will. By now you should clearly understand the links between the atmosphere, climate, and the water cycle. You should have a basic understanding of how water interacts with the lithosphere, though we will explore this in more detail in the next unit. You should also know that freshwater in the Critical Zone is unevenly distributed on Earth and that this leads to variations in the character of and processes operational in the Critical Zone from region to region.
Please read the following manuscript to solidify your understanding of the links between surface and groundwater quality and quantity and the surrounding landscape.
This is an excellent review of much of the material covered in Unit 4—pay particular attention to the schematic figures. Also, note the attention placed on human interactions with the water cycle. As you do so, begin to think about the role of humanity on your study site –(your site is probably not pristine even if it is located in a state or national forest), as you will be required to assess the impact of past, present, and potential future human impacts on your site as part of your semester project.
Let's take some time to reflect on what we've covered in this unit!
For this activity, I want you to reflect on what we've covered in this unit and to consider how you might adapt these materials to your own classroom. Since this is a discussion activity, you will need to enter the discussion forum more than once in order to read and respond to others' postings.
You will be graded on the quality of your participation. See the grading rubric [47] for specifics on how this assignment will be graded.
This lesson on groundwater was crafted to introduce you to the fairly complex concepts of hydrogeology and groundwater flow. You should understand that some water that arrives at Earth's surface infiltrates into the ground. An unsaturated zone exists between the ground surface and the water table, beneath which lies the saturated zone of groundwater flow. Where recharge to the water table occurs freely without barriers to flow, unconfined flow systems exist. In some places, groundwater is confined—disconnected from overlying solid material and water outside of its recharge area. Surface water and groundwater can be in hydrologic communication in other ways, for example as gaining or losing streams.
Groundwater flows through spaces in the sediment and rock beneath our feet: a continuum exists in flow regimes between diffuse flow and fracture or conduit flow. Groundwater quality is affected by natural and anthropogenic processes. In some places, groundwater can be naturally degraded by proximity to geologic materials, but the majority of groundwater quality concerns are due to human activities, such as agriculture, industry, and waste disposal. Because of water's role as a solvent, and its intimate relationship to the sustenance of life, all of the processes you've learned about in this unit are important for furthering your understanding of Critical Zone processes. Remember, agua es vida.
You have finished Lesson 7 and Unit 4. Double-check the list of requirements on the Lesson 7 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
Thus far through the course, we have focused on one of the state factors of soil formation: climate. (We have also studied how water specifically contributes to this process.) Now we turn our attention to the other state factors. In this unit on geology and landforms, we will consider and discuss three of the remaining four natural state factors of soil formation: parent material, topography, and time.
Parent material is obviously a critical component of the pedogenic system and the Critical Zone—all the other state factors of soil formation act upon the parent material to create soil, and thus the original, unweathered composition of the parent material plays a unique role in the weathered product. In Lesson 8, you will learn (review) basic concepts of geology to remind you that rocks and sediments have widely ranging textures and compositions formed in a wide range of environments. These variations, in turn, can affect soil formation and Critical Zone processes.
The landforms and topography of a region control a variety of Critical Zone processes. You will learn in Lesson 8 that the plate tectonic setting plays a first-order role in determining the topography of a site and thus in determining whether soils develop and accumulate or are subject to erosion. In addition, the geologic setting determines other aspects of environmental control on the Zone. As you study Lesson 8, consider the following questions: Can unique depositional environments consist of characteristic landforms? If so, what can those landforms show us about Critical Zone processes? Do soils developed on unique landforms have unique characteristics? What is the slope and aspect of a site and how do these relate to solar heat budgets and vegetation?
The geology of a region controls the parent material available for pedogenesis. Parent material can be represented by a wide range of rock types of varying geochemical compositions, it can be lithified (hardened) or unconsolidated, and it can be relatively recent in age or billions of years old. The geologic setting of a region, past and present, also determines whether or not mountains or valleys exist, thereby exerting a first-order influence on the topographic setting in which Critical Zone processes function and soils form. Furthermore, the geologic setting will determine whether parent material lies within an active setting, perhaps only recently exposed to pedogenic processes; or within a more stable setting in which soil formation may continue unabated, subject only to the vagaries of climatic and biotic change.
By the end of this lesson you should be able to:
Lesson 8 will take us one week to complete. As you work your way through these online materials for Lesson 8, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 8. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Report (2 pages) on parent material questions | pages 4, 7 | Post to the Lesson 8 - Geology dropbox in Canvas |
Report (2 pages) with relevant maps | page 8 | Post to the Lesson 8 - Geologic Map dropbox in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
Geology is near and dear to my life since I am a geologist. I cannot count the number of times I have been asked whether or not I have been out on a "dig" recently or whether I dug up any arrowheads or pottery during my recent field excursions. Geology is not archaeology! For this reason, I want to be sure that you are exposed to some basic information about geology, including a definition. Be aware that geology is a science subdivided into numerous sub-disciplines and that numerous university geoscience departments around the world offer degrees ranging from two-year associate's degrees to the Ph.D. This lesson should be viewed as an introduction to only the very basics of geology!
A set of talks covering various topics within the Geosciences is available for free use in schools at Your Planet Earth [131].
The Pennsylvania Topographic and Geologic Survey provides online resources for teachers [132], including lesson plans, relating to the geology of Pennsylvania. Visit the site and follow the hyperlink "For Teachers" to "Lesson Plans." Other states may offer similar resources.
Please visit and read the following sites to be certain that you understand the basics of the field of geology.
Once you have completed that reading, you should understand that geology is the study of Earth: the materials of which it is composed, the processes that created those materials, and the history of the planet.
Much of what geologists work on focuses on rocks, classified into three basic types: igneous, sedimentary, and metamorphic.
Please visit the "Geology" section of About.com [135] to learn more about rocks.
You will be asked some questions related to these readings in the following activity.
For this activity, I want you to begin writing a two-page report that you will continue working on in another activity in this lesson.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L8_geologydocument_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L8_geologydocument_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Geologists use the term rock cycle to describe and simplify the complex interactions through which the three rock types can be linked to the processes that created them. One version of the rock cycle is illustrated below.
A simple animation of the rock cycle can be viewed at Exploring Earth [137]. Follow the links through steps 2 and 3, ignoring the assignment in step 3.
The rock cycle is driven by plate tectonics and the presence of water. To review some basic information about plate tectonics, visit and read:
Notice that oceanic crust is denser than continental crust, hence continents exist above sea level and they are a net source of sediment to the ocean basins. Also note that each plate boundary type is described by characteristic processes, some of which lead to the development of uplifted regions, while others lead to downwarped or subsided portions of crust. Subsided areas often contain thick sediment piles full of relatively fresh bedrock and mineral nutrients derived from the nearest uplifted zones. For example, where the Indian sub-continent has collided with Eurasia, a large mountain belt has risen, the Himalayas, from which enormous quantities of sediment are shed into the Bay of Bengal.
Tectonically active regions of Earth typically display characteristics and landscapes that are different from less active, more stable regions of the planet. In the next lesson, you will learn about the unique features of five geomorphic environments and settings. But now, while you've been thinking about plate tectonics, I want you to view images of landforms from tectonically active regions [140]; remember these when you study the five geomorphic environments later.
Obviously, much of the rock cycle includes processes which operate deep within Earth's interior, the details of which fall well beyond the purview of this course. While it is important to understand that these processes occur, in this lesson we will focus on those portions of the rock cycle that are immediately relevant to and operate within the Critical Zone: weathering, erosion, and deposition. To fully understand these processes, it is as important to know the rates at which they are active, which often requires the perspective of geologic time.
Geologists have a much different sense of time than most of our fellow citizens of Earth. It is not unusual for me to tell friends and family about my studies of the most recent episode of past greenhouse warmth, ~50,000,000 years ago, as an analog to Earth's not-too-distant globally warmed future, and in return be subject to gaping jaws or glazed eyes. Geologists' perception of time derives from our study and understanding of the history of Earth and the vastness of geologic time. Often these concepts conflict with Biblical interpretations of geologic time; nevertheless, the majority of geologists know and accept that features like the Grand Canyon did not form in 6,000 years. Personally, I find the vastness of geologic time to be much more inspiring! But like the rest of you, I still wish my weekends and vacations were longer.
Recall from the lesson on soils that time is one of the five natural state factors of soil formation. A parent material long subjected to the forces of climate, topography, and biota is more likely to develop into soil than one subjected to only brief exposure to those factors. Following from that, the structure, texture, and horizonation of a soil can and often will become more developed and mature with time. Also, remember from the paleoclimatology lesson that paleosols exist and provide a record of the history of the Critical Zone through time. Billions-of-years-old paleosols are known to exist, providing witness to the evolution of the Critical Zone.
To learn about various aspects of geologic time, including the methods that allow us to measure geologic time and their development, visit and read:
View the figure below, being sure to note the human figure in the Pleistocene Epoch—human history represents only a small fraction of all of Earth history, yet as we will learn in future lessons, we have quickly become the dominant force in shaping Earth's surface.
As important to understanding the vastness of geologic time is the perspective it brings to understanding the rates of surface processes in the Critical Zone. Visit "Chapter 6: Geologic Time, Geologic Processes Past and Present - Uniformitarianism [143]" and focus on the description of uniformitarianism versus catastrophism.
Also, see "Geological Time [144]" for issues relating to teaching about geologic time and the notion that it requires innovation in our sense of reality.
Weathering describes the chemical and physical decomposition of rocks and minerals through contact with our atmosphere. Rocks and minerals subject to weathering are not moved during decomposition. In contrast, erosion involves the entrainment and transport of rock and mineral particles by wind, water, ice, and gravity; a reduction in velocity of the transport medium or increase in resistance of the transported particles results in deposition or the addition of material to the landscape. Note that biota (i.e., biogeomorphology [145]) can play an important role in both weathering and erosion.
To learn more about the processes of weathering, erosion, and deposition, please visit and read the following:
In addition, read:
which is located in Library Reserves, so that you can develop a more evolved view of the relationship between these processes and the concept of the Critical Zone as a "feed-through reactor."
You will be asked some questions related to these readings in the following activity.
For this activity, I want you to complete the two-page report you began on page 4 of this lesson.
Upload your report to the "Lesson 8 - Geology" dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Geologists use and create a variety of maps to display the results of our work. Among the simplest of these are maps of bedrock and surficial geology. Bedrock maps display the various rock types in a region. They are best understood if you can imagine stripping away all of the unconsolidated sediment, soil, and vegetation from the land surface down to solid rock. Bedrock maps do not indicate that XYZ rock type can be found at ABC locale; instead, they show what exists in the subsurface beneath the soil and sediment and vegetation. In some places, particularly out west, rocks do exist at the surface! In that case, the bedrock map shows the rock type at the surface.
Surficial geologic maps differ from bedrock maps in that they display the sediments mantling bedrock. In some places, no sediment exists and, therefore, the surficial map may show bedrock. But in others, for example in northeastern and northwestern Pennsylvania (where multiple glaciers dumped their sediment load over the past several hundred thousand years), surficial geologic maps differentiate between the various materials moved into the region by glaciation and may even differentiate between deposits of different ice ages.
Now let's take a look at the geologic maps available for your study site.
L8_geologicalmaps_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L8_geologicalmaps_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your report to the "Lesson 8 - Geologic Maps" dropbox in Canvas (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Geology, the study of Earth, is a broad and complex discipline. In this lesson, you reviewed some geologic concepts, including the difference between the three basic rock types. You read briefly on plate tectonics, geologic time, the rock cycle, and various related processes focusing on weathering, erosion, and deposition. I asked you to consider several questions regarding the role of parent material, erosion, and deposition on soil formation. Finally, various types of geologic maps were explored—the accessibility and usefulness of these resources are the most important lesson for you to draw here.
You have finished Lesson 8. Double-check the list of requirements on the Lesson 8 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
In the last lesson, you were introduced to the concept of the Critical Zone as a feed-through reactor (Anderson et al., 2007). As we move forward in this unit, I first want you to consider the relationship between the feed-through reactor and isostasy [151]. Imagine a mountainous setting in which active erosion constantly removes weathered material from the summits: the unloading of weathered material allows the underlying crust to readjust by uplift, thereby physically raising unweathered rock rapidly into the feed-through reactor. Eventually, the landscape may mature to one with low topography and little relief as the deep crustal root has been exposed, weathered, and brought toward isostatic equilibrium with the underlying mantle. Thick soil profiles develop and blanket underlying unweathered rock, slowing the rate at which the unweathered rock is processed through the reactor. Furthermore, recall from Lesson 2 (reading Brady and Weil, pp. 41–2 and 61–2) that topography is the configuration of the land surface described in terms of elevation, slope, and landscape position differences, and that topography can hasten or retard the effects of climate on parent material-weathering by creating a balance between erosion and pedogenesis.
Because topography often reflects the distribution of different parent materials in many landscapes, detailed soil maps can be useful for interpreting geology, and geological maps can in places be made directly from soil maps [Birkeland, P. W. (1999). Soils and Geomorphology (3rd ed.). New York: Oxford University Press, p. 31]. Mappable soil bodies typically display patterns of distribution based on underlying bedrock and landforms—to fully understand soils one must make an in-depth assessment of geomorphic settings (Birkeland, p. 49, p. 1).
Having considered the variables associated with bedrock type, the rock cycle, tectonic setting, weathering and erosion in the last lesson, now we will explore geomorphic environments and the processes that can move and shape them to learn about the links between landforms, soils, and the Critical Zone. I'll remind you here, as I did in Lesson 2, to consider the outstanding question in Critical Zone science learned in a Lesson 1 reading (Brantley et al., p. 11): Can a unified approach be developed to characterize environmental conditions and mechanisms that produce different soil types?
By the end of this lesson you should be able to:
Lesson 9 will take us one week to complete. As you work your way through these online materials for Lesson 9, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 9. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Report (1 page) on topography and feed-through reactor at your study site | page 2 | Post to the Lesson 9 - Catena dropbox in Canvas |
Respond to question on aerial photo availability in your state Report (1 page) on aerial photo analysis |
page 8 |
Email directly to Tim Post to the Lesson 9 - Aerial Photo dropbox in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
A remarkable aspect of Earth's surface is the seemingly infinite variety of landforms. However, some landforms possess certain characteristics that differentiate them from other landforms, a fact that is fundamental to geomorphology [152], the field-oriented study of landforms at the interface between geology and many other disciplines working to understand surface processes. The applications of geomorphic knowledge can range from engineering projects dealing with the physical properties of landforms to geological studies of the record of past climate change recorded by landforms. It is this overall lack of rigid philosophical boundaries that may be geomorphology's greatest attribute—interdisciplinarity (Ritter, D. et al., 2002, Process Geomorphology, 4th edition, p. 1–2).
Diversity in the Critical Zone is displayed by the distribution of soils across landforms, reflecting variable chemical and mechanical weathering processes as well as physical erosion and chemical denudation. These processes, in turn, control the internal structure of the Critical Zone, the feed-through reactor of Anderson et al. (2007), through which changes in surface area, flow paths, and material residence time impact element and nutrient weathering fluxes.
In succeeding sections 3 through 7 we will explore five classes of geomorphic environments and the processes that occur with them. Before we launch into this more detailed study, I want you to more fully understand basic concepts of topography, including the influence of slope orientation or aspect on pedogenesis, by completing the following activity.
L9_catena _AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L9_catena _eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your paper to the "Lesson 9 - Catena" dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Complete the following reading assignments:
Wind can be an effective geomorphic agent. Obviously, the presence of regular and/or strong wind is required for a specific landscape to be dominated by wind erosion and deposition, but various physical properties are also important. For example, regions showing a paucity of vegetation or preponderance of unconsolidated sediment are more susceptible to wind erosion.
Complete the following reading assignments:
In an activity in Lesson 4, you learned about the formation of glaciers and the role and effect of glaciers on climate. Now we turn our attention to some of the most spectacular landscapes on Earth—the result of glacial erosion and deposition. Understanding glacial motion, recorded in glacial landforms, is fundamental to current considerations of ice sheet meltback, sea level rise, and global climate change.
Complete the following reading assignments:
Remember my visit to Bear Meadows in Lesson 3? You might want to re-watch that video to refresh your memory . . .
Glacial geomorphology has proven quite useful to planetary geologists interested in understanding the evolution and history of the surface of nearby planets in our solar system. Visit the following hyperlink for a brief introduction to glacial geomorphology and Mars.
You may find the following resources useful in your classroom:
Unique landforms and patterns of drainage called karst or karst topography primarily form in temperate to tropical regions, though they are found in arid and polar regions too. The common feature shared by all karst landscapes is that they are underlain by chemical sedimentary rocks particularly susceptible to dissolution, carbonates and/or evaporites. The landforms result mostly from chemical weathering of the host rock and the progressive integration of subsurface cavities, though collapse into solution cavities can also be important. Karst landscapes are often dominated by underground drainage networks that interrupt and capture surface water flow.
For a relatively succinct definition of karst, from the Canadian perspective, follow this hyperlink:
Of the karst-forming rocks, the carbonates (dolostone and limestone) are much more abundant than evaporites (mostly deposits of gypsum and anhydrite), therefore karst landscapes are most often found in regions underlain by carbonate rocks. The following Web site will help you learn more about limestone karst, including information on the relationship between lithology, porosity, permeability and karstification, the distribution of karst lands in the United States, the driving mechanics of karst processes, and links between surface water flow, aquifers, and groundwater.
To learn about the distribution of karst landforms in central Pennsylvania, the relationship to lithology, and groundwater flow, watch the following video of my visit to Tussey Sink.
Some basics of karst processes and landscapes focused on caves are presented at Teachers' Domain as "I [165]ntroduction to Caves and Karst." [166]
Nearshore coastal environments host most of humanity, at the interface between the vast oceans that cover 70% of Earth and the continents, home to all our soil and the Critical Zone. The oceans possess energy that is transferred to and manipulates land through erosion and deposition. Humanity's land use has greatly strained coastal environments; therefore, a thorough understanding of coastal processes betters our chances of sustaining life and human endeavors in this very dynamic environment. Be aware that these concepts apply to shore lines along large lakes, too!
To learn about shoreline processes and coastal evolution, wave refraction and erosion, sediment transport and deposition, and submergent and emergent coastlines through a series of schematic diagrams, follow this hyperlink:
More information on classification, with nice imagery, can be studied at:
The following two hyperlinks lead to other reviews of coastal processes and landforms, as well as wave refraction, erosion, and deposition, importantly with nice images:
To view a slide show covering coastal erosion, corrasion and corrosion, subaerial procesess, and coastal classification, including nice images of headlands and bays, wavecut notches and platforms, cliffs, sea caves, and arches, and the stages of coastal development, see:
While field studies are essential for understanding the geomorphic environment or setting of a region, remote sensing imagery—specifically easily obtained aerial photographs and satellite imagery—provides a broad overhead view, a context in which to place field observations. For this reason, in this section of the landform lesson, we will explore various online resources that provide overhead imagery. Before you begin the following activity, go to Fluvial/Deltaic/Coastal Landforms [172] and Karst/Lacustrine/Aeolian/Glacial Landforms [173] to view aerial photographs representative of the major geomorphic environments presented in sections 3 through 7 of this lesson.
L9_remotesensing_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L9_remotesensing_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your report to the "Lesson 9 - Remote Sensing Report" dropbox in Canvas (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Go to the NASA website and view the learning module Blue Marble Matches [181] - you may find it to be something to introduce into your classroom!
In this unit, we have focused our attention on the lithosphere and explored a number of aspects of geology and geomorphology, mostly focused on parent material and topography factors in soil formation. It should be clear to you that Earth's surface is covered by landscape elements that can be classified according to processes and landforms unique to those processes. You should also know that while geomorphology and geology are field-oriented sciences, the study of remotely sensed imagery can greatly enhance our understanding of a landscape and the processes that formed it. Considering the resources you've been introduced to in this lesson, you should also now know how to obtain such imagery for your own use.
You have finished Lesson 9. Double-check the list of requirements on the Lesson 9 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
The variety of life on Earth exists as a myriad of microscopic and macroscopic forms. This biological diversity, or biodiversity, can be described at scales ranging from planetary, biome, or ecosystem to site-specific. Biodiversity includes genetic variation within species, the variety of species in an area, and the variety of habitats within a landscape. Roughly 1,750,000 species have been described and formally named, though estimates of the total biodiversity of life on Earth range from 5 to 30 million, with some estimates as high as 100,000,000 total species.
Most of terrestrial life reproduces, feeds, lives, and dies in the Critical Zone (see "Soil Biodiversity" [182] at Wikipedia for a brief introduction to soil biodiversity topics). Soil is intimately linked to biodiversity: soil provides the substrate through which much of the terrestrial biosphere interacts with the Critical Zone and its other component "spheres," and biota exert a significant influence on soil formation and Critical Zone processes. For example, plants absorb atmospheric carbon dioxide and store it in roots—eventually root respiration adds carbon dioxide to the soil atmosphere, changing, and at times controlling, weathering rates and other chemical processes within the soil and Critical Zone. A primary function of roots is to absorb water and nutrients, activity that directly influences the hydrosphere by drawing in soil moisture and dissolved constituents. This influences recharge rates and the chemistry of the soil and groundwater system. Roots also anchor plants within the Critical Zone and physically erode rocks by penetration and wedging, thus influencing interaction with the lithosphere.
But it is yet more complicated than that! Each species or organism may have a unique role in an ecosystem and therefore may interact with the Critical Zone in a different way. Furthermore, the interactions between organisms can be unique to species or unique to a specific habitat or ecosystem. Let's think about plants again. Cellulose, a potential source of energy, is tough and insoluble to most organisms. But termites (and grazing animals) contain microorganisms in their digestive tracts that convert cellulose to sugars usable by them and their hosts. Thriving termites in turn clear the landscape of dead plant litter, recycle contained nutrients back to the soil, and enhance soil porosity and permeability through construction of their subterranean chambers. An overall decrease in soil productivity and fertility has been observed in the absence of termites; thus, if not for those gut flora, a substantially different, and perhaps less fecund, ecosystem might exist.
Most cultures have recognized the importance of biodiversity for boosting overall ecosystem productivity and resilience to disasters. Yet continued destruction of habitat and species by human society is leading to what some biologists and paleontologists call the “Sixth Extinction,” perhaps the most rapid and destructive of extinctions in Earth history. Imagine total global human destructiveness perhaps exceeding the comet impact that occurred at the end of the Cretaceous [183] Period that finished off the dinosaurs!
In Lesson 10, we will consider the various means by which biologists and other natural scientists classify life on Earth. From there, we will launch into concepts of ecology, examining some of the interactions and processes between organisms and their environment—this examination will gradually focus in on the Critical Zone and soil processes that involve biota. We will complete Lesson 10 with an online forum to discuss the merits of placing a financial value on ecosystem processes. In Lesson 11, we will take a closer look at various expansive ecosystems of Earth and consider the relationship between them and the rest of the Critical Zone.
Learn about some interesting examples of the role of life in the Critical Zone.
In this lesson, we will examine basic ecological processes, eventually focusing through reading on links to the Critical Zone. This knowledge will prepare us for a closer examination of ecosystem-scale Critical Zone processes in Lesson 11 and our consideration of human interactions in the Critical Zone, in the manner of Earth system science, in our final lesson.
Lesson 10 will take us one week to complete. As you work your way through these online materials for Lesson 10, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 10. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMITTED FOR GRADING? |
---|---|---|
Report on "Site-specific ecological processes" | pages 3, 5, & 6 | Submit to the "Lesson 10 - Ecological Processes" dropbox in Canvas |
"Merits of Valuing Ecosystem function" | page 7 | Post to the "Lesson 10 - Ecosystem Value" discussion forum in Canvas, then discuss |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
Before we begin to explore the main topic of ecological processes in the Critical Zone, I want you to first study and consider biodiversity.
To learn more about the measurement, distribution, and control of the biodiversity of life on Earth, please visit and read:
Next, read the following article, located through Library Reserves:
Enjoy this reading. Learn that the upper reaches of the Critical Zone in an Ecuadoran forest canopy contains ~42,000 insect species per 2.5 acres. View and study the figure entitled "Life's rich tapestry" on pages 21–22. Note that the maintenance of biodiversity is attributed to a wide variety of microhabitats and environments in genetic studies of soil bacterial microdiversity, as the tropical-like variety of plant species in temperate South Africa is similarly maintained, whereas in dry central Australia the type and amount of vegetation dictate animal diversity.
As you reflect on what you just read, complete the following activity.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L10_ecologicalprocesses_AccessAccountID_LastName.doc (or .pdf). For example, student Elvis Aaron Presley's file would be named "L10_ecologicalprocesses _eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
The myriad variety of life is classified in a number of ways, dependent on scientific questions and need. Scientists utilize taxonomy to name and classify organisms, and they use systematics to create phylogenies—the evolutionary history of a species or group of species. Perhaps the most commonly known classification scheme utilizes evolutionary relatedness and a hierarchy of increasingly exclusive categories: domain, kingdom, phylum, class, order, family, genus, and species.
The following hyperlink provides a nice classroom Powerpoint slide show: Naming and Classifying Organisms [190].
Ecology, the study of the interactions between organisms and the environment, can be arranged into categories mostly based on increasingly generalized interactions between multiple organisms and their habitat. For example:
For this activity, I want you to continue working on the 3–4-page paper that you began on page 3 of this lesson.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
The Earth's surface hosts a dynamic interplay of biotic and abiotic processes, all of which support the self-sustaining system that is the Critical Zone. The looming disaster associated with human activities and dominance of nature, however, threatens the balance of natural processes and challenges science to better understand the resilience of ecosystems and the CZ.
For this activity, I want you to complete the paper you have been working on for this lesson (see pages 3 and 5).
Upload your paper to the "Lesson 10 - Ecological Processes " dropbox in Canvas (see the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
Much of humanity tends to be oblivious to the role of nature in their lives. In North America, water comes from a faucet, food is gathered from stores, and toilets remove our waste. In less industrialized nations, much of the populace is too poor to concern themselves with natural ecological processes (though such processes may benefit their lives) as they deal more directly with poverty, hunger, and disease. But as the effect of humanity on nature has begun to deteriorate our lives and increase the need for engineering responses to our degradations, more scientists, planners, and citizens have begun to realize the value of a healthy, operational Critical Zone—various groups have gone as far as to estimate the financial value of such processes while others argue that such a move denigrates the natural world and attitudes toward it. You will read about this debate in the following activity.
Upon completion of the reading, you are to engage in a discussion of the readings with the rest of the class. The class discussion will take place during the week of this lesson in a discussion forum in Canvas titled "Lesson 10 - Ecosystem Value Discussion."
You will be graded on the quality of your participation. See the grading rubric [47] for specifics on how this assignment will be graded.
To learn more about valuing ecosystem services, read the original Costanza et al. paper published in the elite journal Nature:
Costanza, R., d'Arge, R., de Groot, R., Farber, S., Grasso, M., Hannon, B., et al. (1997).The value of the world's ecosystem services and natural capital [195]. Nature, 387(6630), 253–260. doi: 10.1038/387253a0.
You may also find this Nature Comment by Costanza and Kubiszewski [196] equally provocative and interesting.
Most of humanity forgets that pollinators and trees and the sun work for free, providing some of the many ecosystem services that benefit us. Listen to Paul Sutton, a geography professor at University of Denver who has calculated a dollar price of these services, explain how he made the calculations on this June 2014 edition of Living on Earth.
Nature's Dividend: ”Pricing Global Ecosystem Services"
Living on Earth [197]
To learn about the concept of Critical Zone services, read the paper by Field et al. (2015) [198].
This lesson briefly touched on the complexity of life on Earth and the interactions between organisms and their environment. It is important to recognize that the Critical Zone is so named because it is this thin veneer at Earth's surface that supports life on our planet—yet life also plays a complex and vital role in shaping and sustaining the zone. In the next lesson, we will study in more detail the complexities of various biomes and ecosystems and their role in CZ function. We will also evaluate the relationship between biomes and soils, and learn how to make site-specific determinations of landscape types.
You have finished Lesson 10. Double-check the list of requirements on the Lesson 10 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
The last lesson began with an introduction to biodiversity, including soil biodiversity, and moved on to study the classification of life, based on evolutionary relatedness, nutritional mode, and trophic levels. We completed the lesson by thinking about the interactions between organisms (ecology) and the value of ecosystems to human society. In this lesson, we will focus on sets of ecosystems or biomes, their character, and their relationship to the rest of the Critical Zone. We will revisit key concepts and observations learned in earlier lessons on soil, climate, and landscapes. You will then learn to access land cover maps available through the USGS to determine the natural character and human land use of your site. Finally, we will consider the ecology of soils in some detail.
By the end of this lesson you should be able to:
Lesson 11 will take us one week to complete. As you work your way through these online materials for Lesson 11, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 11. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Report (3-page) on biotic links to the CZ, land cover, and soil ecology | page 3, 4, and 5 | Post to the Lesson 11 - Biomes dropbox in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
One manner in which to consider the term biome is as a set of ecosystems with characteristic biota—the first-order effects of climate determine the location of biomes on Earth. The interrelationship between climatic and biotic processes with the landscape and parent material determines the flow of energy, water, and nutrients in the biome. Soil and Critical Zone processes can be distinctive to a biome, thus soil and Critical Zone character and function can be considerably different from one region of Earth to another.
To learn more about biomes read:
You may also find that the following Flash animation from Teachers' Domain to be useful now and in your classroom:
As you read this chapter, reconsider briefly the information on terrestrial ecosystems presented in the Lesson 10, page 5 reading assignment [201].
Once you dive into Raven et al., be sure to...
In a previous soils lesson activity, you were asked to study and describe the relationship between soil distribution and latitude. Subsequently, in the climate lesson, you read about the distribution of different climates on Earth and the Koeppen climate classification system. Now I want you to briefly compare the relationship between biomes and climate using the Koeppen classification.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L11_biomes_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L11_biomes _eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Land cover maps are available from the USGS—the maps characterize the natural environment as well as the land use. Depending on the year and other factors, twenty-one land-use categories have been applied to the United States.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
Now that we've spent the better part of two lessons studying ecosystem and biome scale processes, I want you to focus especially on soil organisms, soil biodiversity, and the ecology of soils.
For this activity, I want you to complete the paper you have been working on for this lesson (see pages 3 and 4).
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
Upload your paper to the "Lesson 11 - Biomes" dropbox in Canvas (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
The elite journal Science ran a special section entitled "Soils—The Final Frontier" in June 2004. We will read several articles from the special section in Lesson 12; the following three provide further insight and knowledge on the topic of soil ecology and soil biotic processes.
To learn about the effects of invasive earthworms on soils see Non-native invasive earthworms as agents of change in northern temperate forests [212].
In this second lesson of the biota unit, you considered the complex interrelationship between climate and biota with the landscape and parent material that determine the flow of energy, water, and nutrients in biomes. You also learned that soil and Critical Zone processes can be distinctive to a biome or to a particular region of Earth. You looked at global-scale trends in these relationships and considered the various factors that may describe some of the disparities in these global-scale relationships. You also learned about the primary contributing factors to soil ecology and biodiversity and applied this knowledge to your study site. Finally, you learned where and how to access land cover maps.
You have finished Lesson 11. Double-check the list of requirements on the Lesson 11 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
At this stage in your career, you should have encountered the term Earth system science, primarily used to describe the science (especially quantitative modeling) of the interactions between the atmosphere, hydrosphere and cryosphere, and biosphere. It should not require a huge leap in logic to see that the addition of lithosphere to that list provides all the components ("spheres") of the Critical Zone that we've studied this semester.
For a reminder and useful classroom video, see "Earth as a System [213]," a Quicktime video on the Teachers' Domain Web site.
Systems (in our case, the Critical Zone) consist of components (the "spheres"). The components are not isolated. Instead, they typically interact in complex ways; systems may also interact with other systems. These interactions, or linkages, are called couplings in Earth system science vocabulary. Positive couplings mean a change in one component, whether positive or negative, causes a change in the same direction in a linked component, whereas negative couplings mean the linked component undergoes change in the opposite direction. Feedback loops are circuits of change and response to change: negative feedback loops typically diminish the effects of change, whereas positive feedback loops usually amplify the change.
The state of a system is described using the characteristics of the system at a particular time. Changes to the state of a system are caused by (1) interactions between other systems and (2) interactions among the components within a system. An equilibrium state will not change unless the system is disturbed. Temporary disturbances to a system are called perturbations, whereas persistent disturbance is called forcing. When slight disturbances carry a system further from equilibrium it is said to be an unstable system.
In this final lesson of the semester, you will be introduced to some of the basic concepts of system modeling. We will accomplish this through a series of readings and an activity. The readings will introduce you to the basics of system modeling and some of the specifics (including quantification) of human impacts to the biosphere, atmosphere, hydrosphere, lithosphere, and soil (i.e., the Critical Zone). Your final task for the semester will be to create a qualitative Critical Zone system model.
Lesson 12 will take us one week to complete. As you work your way through these online materials for Lesson 12, you will encounter additional reading assignments and hands-on activities. The chart below provides an overview of the requirements for Lesson 12. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Create qualitative Critical Zone system model | page 3 | Submit to the "Lesson 12 - CZ System Model" dropbox in Canvas |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
The goal of this final lesson is for you to create your own qualitative Critical Zone model, recognizing that the Critical Zone is a very complex system with human and natural components.
For this assignment, you may do your work by hand (e.g., pen/pencil and paper), in a word processing document, or using a drawing program of your choice. No matter what you choose, your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it.
L12_cz_system_model_AccessAccountID_LastName.doc (or .pdf)
For example, student Elvis Aaron Presley's file would be named "L12_cz_system_model_AccessAccountID_LastName.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your paper to the "Lesson 12 - CZ System Model" dropbox (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
The activity entitled "Exploring environmental change [216]" provides an additional or optional mechanism for classroom introduction of the basic concepts of modeling an Earth system.
Humanity's impact on the Critical Zone is immense and often mostly negative, in the sense that the characteristics of and processes in the zone are diminished by our actions. By now you should have a sense that there are consequences to these actions and that the current status of humanity's relationship to the Critical Zone is not sustainable.
To learn more about human interactions with the various components ("spheres") of the Critical Zone system, complete the following reading assignment. As you do so, be sure to search for information regarding the characteristics, processes, and couplings of each component that may help you build your qualitative Critical Zone system model.
Articles not directly linked are located in Library Reserves.
To learn more about the basics of human population growth and effects on natural resources visit Population Education [219]. Pay particular attention to the "Environmental Connections" link and notice the teaching materials and tools, teacher services and workshops, and the free newsletter for teachers".
To consider an important view of tropical deforestation links to agriculture, food security and sustainability, see Iowa in the Amazon [220].
Remember that your task in this lesson is to create a qualitative Critical Zone system model, not a soil system model. While soil lies at the "heart" of the CZ, the zone is more than soil—soil may be thought of as a component of the CZ system.
Continue your readings of human interactions with the CZ by considering more specifically some of the effects we have on soil. Use this information to help build your CZ system model. (The articles below that are not directly linked are located in Library Reserves.)
From the introduction to this lesson, remember that human actions can be adaptive or excessive—thus far, much of our activity has been excessive, but we have the capacity to adapt and to be sustainable.
NOTE: The following readings are all available through Library Reserves.
Here are some additional resources that might be of interest:
The Critical Zone is a complex system formed at the intersection of the lithosphere, biosphere, hydrosphere and atmosphere, and including soils. In this lesson, you've learned about system modeling and considered human impacts on the Critical Zone and soil and adaptive measures that society can take to sustain the Critical Zone and soil. You also attempted to qualitatively model the Critical Zone by considering the various processes within each component of the CZ and how they are linked to the other components.
You have finished Lesson 12. Double-check the list of requirements on the Lesson 12 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
Links
[1] http://commons.wikimedia.org/wiki/Image:Mistassini_roadsign.jpg
[2] http://criticalzone.org/
[3] http://criticalzone.org/national/news/story/summary-video-about-the-us-czo-program/
[4] https://www.millenniumassessment.org/en/index.html
[5] https://www.ipcc.ch/report/ar5/
[6] http://books.nap.edu/openbook.php?record_id=9981&page=35
[7] http://www.czen.org/sites/default/files/CZEN_Booklet.pdf
[8] http://criticalzone.org
[9] http://www.czen.org/
[10] http://www.czen.org/sites/default/files/Sustaining-Earths-Critical-Zone_FINAL-290713.pdf
[11] http://www.nsf.gov
[12] http://www.nsf.gov/news/classroom/
[13] http://www.nasonline.org/about-nas/history/archives/milestones-in-NAS-history/organization-of-the-nrc.html
[14] https://www.myhaikuclass.com/arenick/sandiegovirtualfieldtrips1/cms_page/view/4096442
[15] https://www.e-education.psu.edu/earth530/sites/www.e-education.psu.edu.earth530/files/Earth530_Semester_Project_example.pdf
[16] https://www.e-education.psu.edu/earth530/sites/www.e-education.psu.edu.earth530/files/Earth_530_semesterproject__example2.pdf
[17] http://www.thefreedictionary.com/soil
[18] https://cordis.europa.eu/project/rcn/84933_en.html
[19] https://www.nal.usda.gov/topics/soil-resource-management
[20] http://soils.usda.gov/education/
[21] http://forces.si.edu/soils/
[22] https://www.bafu.admin.ch/bafu/en/home/topics/soil/publications-studies/publications/soil-a-precious-natural-resource.html
[23] http://www.earthscienceworld.org/images
[24] http://soilerosion.net/
[25] https://www.youtube.com/watch?v=YucUMhaIDww
[26] https://www.e-education.psu.edu/earth530/1647
[27] https://www.youtube.com/watch?v=mLVFevmwWWE
[28] https://www.e-education.psu.edu/earth530/1644
[29] https://www.youtube.com/watch?v=r8itOXeLm54
[30] https://www.e-education.psu.edu/earth530/1646
[31] https://www.youtube.com/watch?v=UnwS5QmR_AE
[32] https://www.e-education.psu.edu/earth530/1645
[33] http://www.globe.gov/do-globe/globe-teachers-guide/soil-pedosphere;jsessionid=4884A1A6CFBBA7F9275AA2A5EE53D9EC?p_p_id=globegovteacherguideportlet_WAR_globegovcmsportlet_INSTANCE_5esR&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&p_p_col_id=column-1&p_p_col_count=1&_globegovteacherguideportlet_WAR_globegovcmsportlet_INSTANCE_5esR_protocolCat=372023
[34] http://en.wikipedia.org/wiki/Soil_profile
[35] http://ufdc.ufl.edu/l/IR00003107/00001
[36] http://nesoil.com/properties/color/index.htm
[37] http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1130447039&topicorder=4&maxto=10
[38] http://en.wikipedia.org/wiki/Soil_survey
[39] http://www.nrcs.usda.gov/wps/portal/nrcs/site/national/home/
[40] http://websoilsurvey.nrcs.usda.gov/app/
[41] http://en.wikipedia.org/wiki/Soil_classification
[42] https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/edu/?cid=nrcs142p2_053588
[43] https://nhptv.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.soils/soils-around-the-world/#.WZOv64qQzBI
[44] http://www.ars.usda.gov/main/main.htm
[45] http://www.ars.usda.gov/Services/docs.htm?docid=1274
[46] http://www.enviroliteracy.org/article.php/244.html
[47] https://www.e-education.psu.edu/earth530/node/1650
[48] https://www.nasa.gov/goddard
[49] http://www.ipcc.ch/
[50] http://www.teachersdomain.org/resource/ess05.sci.ess.watcyc.oceancur/
[51] http://en.wikipedia.org/wiki/Climate
[52] http://www.blueplanetbiomes.org/climate.htm
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[54] http://www.pbslearningmedia.org/resource/ipy07.sci.ess.watcyc.albedo/earths-albedo-and-global-warming/
[55] http://www.ncdc.noaa.gov/paleo/ctl/about1a.html
[56] https://www.nesdis.noaa.gov/content/peeling-back-layers-atmosphere
[57] http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter01.pdf
[58] https://www.ipcc.ch/report/sr15/glossary/
[59] http://en.wikipedia.org/wiki/Atmospheric_chemistry
[60] https://climate.ncsu.edu/edu/home
[61] https://www.metoffice.gov.uk/
[62] http://en.wikipedia.org/wiki/Primary_production
[63] http://www.pbslearningmedia.org/resource/b1943ed9-9781-4d75-872f-ee5b26fe28a6/the-roots-of-the-carbon-cycle/
[64] http://www.epa.gov/climatechange/science/causes.html
[65] https://19january2017snapshot.epa.gov/climate-change-science/causes-climate-change_.html
[66] https://grimstad.uia.no/puls/climatechange2/nng01/07nng01.htm
[67] http://www.epa.gov/climatechange/policy/
[68] https://19january2017snapshot.epa.gov/climatechange/evaluating-climate-policy-options-costs-and-benefits_.html
[69] https://toolkit.climate.gov/
[70] http://www.epa.gov/climatechange/emissions/ind_calculator.html
[71] http://www.carbonfootprint.com/calculator.aspx
[72] http://greenfootstep.org/
[73] http://www.footprintnetwork.org/en/index.php/GFN/
[74] http://www.livescience.com/4180-sahara-desert-lush-populated.html
[75] http://en.wikipedia.org/wiki/Svalbard
[76] http://www.pbslearningmedia.org/resource/tdc02.sci.life.cell.stetteroxygen/life-before-oxygen/
[77] http://www.ncdc.noaa.gov/paleo/paleo.html
[78] http://www.epa.gov/climatechange/science/pastcc.html
[79] https://climate.nasa.gov/evidence/
[80] http://www.epa.gov/climatechange/science/recentcc.html
[81] https://19january2017snapshot.epa.gov/climate-research_.html
[82] http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.esglaciers/earth-system-ice-and-global-warming/
[83] https://e-education.psu.edu/earth530/node/1649
[84] http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.glaciers/
[85] http://www.pbslearningmedia.org/resource/ipy07.sci.ess.earthsys.glacierphoto/documenting-glacial-change/
[86] http://www.teachersdomain.org/resources/ipy07/sci/ess/earthsys/glacierphoto/index.html
[87] http://www.dcnr.pa.gov/Geology/GeologyOfPA/GlacialGeology/Pages/default.aspx
[88] http://en.wikipedia.org/wiki/Laterite
[89] http://books.nap.edu/openbook.php?record_id=10136&page=19
[90] http://www.epa.gov/climatechange/science/futurecc.html
[91] https://19january2017snapshot.epa.gov/climate-change-science/future-climate-change_.html
[92] http://gisclimatechange.ucar.edu/inspector
[93] https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter11_FINAL.pdf
[94] http://www.explainingclimatechange.ca
[95] https://www.ncdc.noaa.gov/monitoring-references/maps/us-climate-regions.php
[96] http://www.grida.no/climate/ipcc/regional/174.htm
[97] http://cpo.noaa.gov/Meet-the-Divisions/Earth-System-Science-and-Modeling/MAPP/High-Resolution-Regional-Climate-Modeling
[98] https://www.c2es.org/document/regional-impacts-of-climate-change-four-case-studies-in-the-united-states/
[99] https://www.ucsusa.org/resources/confronting-climate-change-us-northeast
[100] https://www.e-education.psu.edu/earth530/sites/www.e-education.psu.edu.earth530/files/file/onlineDiscussionRubric.pdf
[101] http://elements.geoscienceworld.org/cgi/reprint/3/5/333
[102] http://www.teachersdomain.org/resource/ess05.sci.ess.watcyc.lifeessential/
[103] https://water.usgs.gov/edu/watercycle.html
[104] http://en.wikipedia.org/wiki/Precipitation_(meteorology)#Ways_of_precipitation
[105] http://en.wikipedia.org/wiki/Atmospheric_circulation
[106] https://www.quora.com/Why-are-deserts-dry
[107] http://en.wikipedia.org/wiki/Monsoon
[108] http://en.wikipedia.org/wiki/Cryosphere
[109] http://earthobservatory.nasa.gov/Features/Water/
[110] http://www.epa.gov/safewater/kids/flash/flash_watercycle.html
[111] http://www.epa.gov/safewater/kids/
[112] http://www.teachersdomain.org/resource/ess05.sci.ess.watcyc.lp_watercycle/
[113] https://www.nsf.gov/news/news_summ.jsp?cntn_id=191016
[114] http://wikiwatershed.org/
[115] http://pubs.usgs.gov/wsp/wsp2254/
[116] http://en.wikipedia.org/wiki/Water_resources
[117] http://extension.usu.edu/waterquality/
[118] https://waterdata.usgs.gov/nwis
[119] http://water.usgs.gov/osw/streamstats/
[120] https://www.pbslearningmedia.org/resource/watsol.sci.ess.water.amdren/acid-mine-drainage-remediation/
[121] https://www.pbslearningmedia.org/resource/btl10.ela.early.itsaph/its-a-p-h/
[122] https://toxics.usgs.gov/
[123] https://climate.nasa.gov/quizzes/soilmoisture-quiz/
[124] http://www.waterencyclopedia.com/Ge-Hy/Groundwater.html
[125] http://water.usgs.gov/ogw/basics.html
[126] http://en.wikipedia.org/wiki/Aquifers
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[128] http://water.usgs.gov/education.html
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[131] http://www.earth4567.com
[132] http://www.dcnr.state.pa.us/topogeo/classroom/index.aspx
[133] http://Geology.com/articles/what-is-geology.shtml
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[136] https://www.uwsp.edu/Pages/default.aspx
[137] http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page01.cfm
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[139] https://visibleearth.nasa.gov/
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[147] http://en.wikipedia.org/wiki/Weathering
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[150] http://ngmdb.usgs.gov
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[157] http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA244855&Location=U2&doc=GetTRDoc.pdf
[158] http://www.earthonlinemedia.com/ebooks/tpe_3e/glacial_systems/outline.html
[159] http://www.revisionworld.co.uk/a2-us-grades-11-12/geography/glacial-environments/glacial-processes-landforms
[160] https://editors.eol.org/eoearth/wiki/Periglacial_processes_and_landforms
[161] https://en.wikipedia.org/wiki/Glaciers_on_Mars
[162] http://www.elcamino.edu/faculty/mreed/physical/101%20Powerpoint/glaciers.ppt
[163] http://www.thecanadianencyclopedia.ca/en/article/karst-landform/
[164] http://www4.uwsp.edu/geo/faculty/lemke/geomorphology/lectures/07_karst.html
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[166] http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.caveintro/caves-and-karst/
[167] http://www.tulane.edu/%7Egeol113/COASTAL-PROCESSES-1a.htm
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[170] http://www.physicalgeography.net/fundamentals/10ac_2.html
[171] http://www.scribd.com/doc/305249/Coastal-Erosion-Processes-and-Landforms
[172] http://priede.bf.lu.lv/GIS/.Descriptions/RST/Sect17/nicktutor_17-4.shtml
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[175] http://landsatlook.usgs.gov/
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[186] http://en.wikibooks.org/wiki/General_Biology/Classification_of_Living_Things/Classification_and_Domains_of_Life
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[217] http://www.worldproutassembly.org/archives/2006/04/the_causes_of_t.html
[218] https://www.ipcc.ch/report/ar5/wg2/freshwater-resources/
[219] http://www.populationeducation.org
[220] http://www.nytimes.com/2013/11/25/opinion/iowa-in-the-amazon.html?pagewanted=all&_r=0
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[222] http://www.sciencemag.org/cgi/content/full/304/5677/1616/DC1
[223] http://www.teachersdomain.org/resource/ipy07.sci.ess.earthsys.arcticland/
[224] http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.organic/