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Unit 6: Moving Forward: Evaluating Impacts of Modern-day Proposals Affecting the Carbon-cycle and Climate

Pete Berquist (Thomas Nelson Community College)
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These materials have been reviewed for their alignment with the Next Generation Science Standards as detailed below. Visit InTeGrate and the NGSS to learn more.


Students study particular "real-world" solutions proposed by scientists and engineers. They evaluate the costs and benefits of the solutions with an emphasis on systemic impacts. Students are expected to choose a solution and defend their choices.

Science and Engineering Practices

Engaging in Argument from Evidence: Evaluate competing design solutions to a real-world problem based on scientific ideas and principles, empirical evidence, and/or logical arguments regarding relevant factors (e.g. economic, societal, environmental, ethical considerations). HS-P7.6:

Cross Cutting Concepts

Systems and System Models: Systems can be designed to do specific tasks. HS-C4.1:

Cause and effect: Systems can be designed to cause a desired effect. HS-C2.3:

Disciplinary Core Ideas

Human Impacts on Earth Systems: Typically as human populations and per-capita consumption of natural resources increase, so do the negative impacts on Earth unless the activities and technologies involved are engineered otherwise. MS-ESS3.C2:

Global Climate Change: Human activities, such as the release of greenhouse gases from burning fossil fuels, are major factors in the current rise in Earth’s mean surface temperature (global warming). Reducing the level of climate change and reducing human vulnerability to whatever climate changes do occur depend on the understanding of climate science, engineering capabilities, and other kinds of knowledge, such as understanding of human behavior and on applying that knowledge wisely in decisions and activities. MS-ESS3.D1:

Natural Resources: All forms of energy production and other resource extraction have associated economic, social, environmental, and geopolitical costs and risks as well as benefits. New technologies and social regulations can change the balance of these factors. HS-ESS3.A2:

Performance Expectations

Engineering Design: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts. HS-ETS1-3:

This material was developed and reviewed through the InTeGrate curricular materials development process. This rigorous, structured process includes:

  • team-based development to ensure materials are appropriate across multiple educational settings.
  • multiple iterative reviews and feedback cycles through the course of material development with input to the authoring team from both project editors and an external assessment team.
  • real in-class testing of materials in at least 3 institutions with external review of student assessment data.
  • multiple reviews to ensure the materials meet the InTeGrate materials rubric which codifies best practices in curricular development, student assessment and pedagogic techniques.
  • review by external experts for accuracy of the science content.

This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see

This page first made public: Jul 15, 2016


In this unit, students will review mock proposals that deal with some aspect of the role of carbon in the environment. Each proposal is based on actual actions proposed to mitigate some aspect of carbon consumption and/or climate change, and as such are considered "real world" scenarios (although somewhat generalized for this exercise). Students will review each proposal for the possible societal, economic, and moral implications if the proposal was pursued on a large scale — for instance, by a single nation or collection of countries. Additionally, students will make recommendations to a fictitious governmental panel on the merits and pitfalls of each proposal and provide well-supported recommendations about whether that government panel should pursue or reject the proposal. Instructors can use this unit as a stand-alone activity, or as a summary activity to comprehensively review, discuss, and assess material presented in this module's earlier units.

Learning Goals

  1. Students will be able to identify a carbon cycle reservoir impacted by a scenario intended to mitigate some aspect of carbon consumption and/or climate change.
  2. Students will be able to describe how the flux (movement) of carbon between reservoirs would be impacted by a specific scenario.
  3. Students will be able to evaluate mitigation strategies for carbon emissions using multiple lines of evidence

Context for Use

This unit is designed for a face-to-face introductory level Earth science or environmental science lecture or lab course, ranging from ~9 to ~25 students; however, the activities can be modified for use with online instruction and/or with classes of different sizes. The activities require short readings at home prior to the in-class portion, small group discussion, and large group discussion. Access to a whiteboard or other means of displaying student comments is desirable.

Description and Teaching Materials

This is a jigsaw-structured activity (read more about Jigsaw activities). The general sequence is:

1.Individual: At home, individual reading and evaluation of selected proposal. Answer a few short questions and prepare to share information about the proposal with small-group members in class.

2. Small group: In class, small-group discussion and evaluation of each proposal. (20 min)

3. Whole class: In class, instructor-facilitated class discussion and evaluation of each proposal. At the end of this discussion, the class will serve as a mock governmental committee tasked with deciding to support or reject each proposal. (20 min)

4. Summative Assessment: In class or at home, students prepare a written statement either supporting or rejecting a proposal of their choice. This statement should include their personal opinions, but also be supported by multiple lines of evidences. (10 min, if done in class)

Individual (at home):

Prior to the in-class portion of this exercise, students choose or are assigned one specific proposal to review. After reviewing this proposal on their own, and addressing specific questions identified below, each student will present the merits and pitfalls of this proposal to a small group of peers (in class). This briefing within the small group should take less than 3 minutes.

Before coming to class, students should review each proposal and:

1. identify which carbon reservoirs are impacted.

2. comment on whether the submitted proposal is presented by a credible organization.

3. identify any logical fallacies that may be presented within the proposal.

4. evaluate the scientific validity of the proposal.


Below are six mock proposals that students will evaluate individually, within a small group, and ultimately as a class. The class should act as a group of "experts" who will review each proposal and make recommendations to a fictitious government panel on whether that government should pursue or reject the proposal. First, students should review a proposal at home. Second, students will break into small groups, with one member in each group representing each proposal. Finally, the class will vote on each proposal, in terms of whether to pursue or reject that proposal, providing justification for their findings.

The proposals are provided either as files to download (immediately below) or with following text:

List of Proposals to Download:

Word format Unit 6 Proposals (Microsoft Word 2007 (.docx) 40kB Aug17 16)

PDF format Unit 6 Proposals (Acrobat (PDF) 81kB Aug17 16)

List of Proposals:

I. Stop Burning Fossil Fuels Immediately (presented by WhaleHuggers, an environmentally-focused nonprofit)

The burning of fossil fuels for energy, transportation, and manufacturing purposes is out of control and identified by the scientific community as a primary driver of climate change. Emissions from these fossil fuels significantly increase the concentration of atmosphere-warming greenhouse gases. It is the moral responsibility of governments across the globe, but especially developed and first-world countries, to immediately curtail these greenhouse gas emissions by rigorously pursing alternative energy resources and taxing carbon emissions to pay for the transition to alternative energy.

For more background see:

Getting Off Fossil Fuels, an article by Alex Wilson

Weather and Climate Basics: What Can We Do?, from NCAR

II. Continue Burning Fossil Fuels but Begin Spraying Sulfate Aerosols Globally into the Atmosphere (presented by PetroPAC, a lobbying group that supports the oil industry)

Fossil fuels are the backbone of the global economy. Without fossil fuels, factories would not be able to produce goods, there would not be sufficient energy to meet global demand, and the transportation of goods would be severely limited. However, burning of these fossil fuels may have an impact on the global climate, including increased atmospheric and ocean temperatures, rising sea level, and the delicate balance of ecosystems. Research has shown, however, that not all materials introduced in the atmosphere have insulating and warming effects; the presence of sulfur aerosols from massive volcanic eruptions actually decreases the amount of absorbed solar radiation by reflecting this radiation back into space, thereby having a cooling effect on the atmosphere. Aerosols, in this context, are tiny droplets of sulfuric acid suspended in clouds. In order to combat global climate change, significant funds must be reserved for geoengineering the global-scale, human introduction of sulfur aerosols into the upper levels of the atmosphere, offsetting the warming effects of warming greenhouse gases.

For more background see:

Aerosols: Tiny Particles, Big Impact, by Adam Voiland, from the NASA Earth Observatory

Atmospheric Aerosols: What Are They, and Why Are They So Important?, edited by Bob Allen, posted on NASA's website.

III. Encourage Phytoplankton Growth through Ocean Iron-fertilization ("presented" by Sebastian Siderophile, a geochemical oceanographer at L'Institute d'Oceanographie in Marseille, France.)

The United Nations Intergovernmental Panel on Climate Change (IPCC), the community of the world's top scientists, identifies carbon dioxide (CO2) as a primary driver of global climate change. While atmospheric CO2 concentrations are on the rise, resourceful solutions to decrease these potent gases become ever important. Photosynthetic organisms absorb CO2 from the atmosphere while in the process of creating life-sustaining sugar compounds. Therefore, increasing the amount of photosynthetic organisms globally will result in a net decrease in atmospheric CO2 and dramatically slow the effects of climate change. We propose taking advantage of the photosynthesizing powers of phytoplankton, which are small critters but abundant throughout the world's oceans, to immediately reduce atmospheric CO2 concentrations. It is understood that phytoplankton populations bloom and flourish when iron is introduced into ocean waters (through chemical weathering of minerals or human intervention). Because these organisms are photosynthetic, an increase in phytoplankton results directly in a greater absorption of CO2 gas from the atmosphere. Iron fertilization of the oceans is an elegant, effective, and simple process that global communities should aggressively and immediately pursue to slow the effects of climate change.

For more background see:

Fertilizing the Ocean with Iron, by Hugh Powell, published in Oceanus Magazine from Woods Hole Oceanographic Institution.

IV. Carbon Sequestration by Capture and Geological Injection ("presented" by Carbon Injection, Limited, an Australian start-up company)

The global carbon cycle describes the dynamic exchange of carbon from multiple reservoirs on Earth. With the increased scrutiny of increasing carbon dioxide on global temperatures, processes that remove carbon dioxide from the atmosphere are important to identify. While there are natural processes that remove atmospheric CO2, they are too slow to be useful. If we as a global community are serious about mitigating the effects of climate change, we must pursue more robust and man-made solutions to atmospheric CO2 withdrawal. Carbon Injection, Limited, hires the most talented minds in the world to geoengineer creative solutions for drawing CO2 out of the atmosphere and safely pumping this CO2 into deep injection wells, far from the atmosphere. At Carbon Injection, we develop plans that convert and upgrade conventional power plants to factories that also absorb CO2. The CO2 is stored under high pressure in liquid form. It is then injected into wells that go down tens of thousands of feet into the most stable and geologically sound subterranean reservoirs. Our plans are adaptable to almost anywhere in the world, meticulously protect shallower drinking water aquifers, and are a true 21st-century solution to the greatest global challenge of our lifetime.

For more background see:

Class VI - Wells used for Geologic Sequestration of CO2 from US EPA

V. Package and Send CO2 into Space ("presented" by Space Disposal, Inc. and RocketMan Enterprises)

We all know it; radical climate change is going on because of all the CO2 and other greenhouse gases introduced into the atmosphere from human activity. We hear all types of solutions, like buying hybrid or electric cars, installing solar panels on your roof, and so on. The fact is, all of these options require big changes to our lifestyle, and change is hard. But, our engineers here at Space Disposal, Inc., have developed technology that will reverse the effects of modern climate change and allow you to live life the way you have always wanted to, without sacrificing your dream car or buying expensive solar panels. In conjunction with our sister company, RocketMan Enterprises, we at Space Disposal, Inc., have developed technologies that capture CO2 from the atmosphere, package the CO2 onto rockets, and send that stuff into space! You release, we capture, and RocketMan takes it away. With potential launch sites situated conveniently throughout all seven continents and within 100 miles of all major cities worldwide, our breakthrough approach will effectively decrease the amount of atmospheric carbon to concentrations experience just before the Industrial Revolution. All you have to do is nothing! Keep living life the way you have always wanted and save the planet at the same time. It is a win-win for all of humanity!

For more background, see:

Should we dump our trash into space?, from

VI. Subsidize Alternative Energy Sources from Carbon Tax ("presented" by Senator Wendy Reyes, Arizona)

The only substantive action to combat climate change is to reduce greenhouse gas emissions released by fossil fuels used in the energy sector. Within the next 10 years we must transition our electrical power generation from fossil fuels to alternative forms of energy. Currently, our alternative energy options (solar, wind, hydrothermal, etc.) are prohibitively expensive, so in order to give these necessary alternatives a fair chance in the energy market, we need to instate a substantial tax on all uses of fossil fuels. The funds generated from this "carbon tax" will then be paid out as subsidies to companies capable of setting up alternate energy sources. Once a majority of power generation is supplied by alternative energy sources, we will immediately see the increase of atmospheric CO2 concentrations slow and perhaps start to decrease, thereby helping the atmosphere trap less and less heat. This carbon tax is a fair and substantive action in order to curb the human input of atmospheric CO2and to curtail the effects of climate change.

For more background, see:

Is a Carbon Tax a Sensible Alternative to Subsidies?, by Jeremy Gottlieb, posted on Mosaic Blog

Options and Considerations for a Federal Carbon Tax, a 2013 article by Center for Climate and Energy Solutions

Small group: (20 min)

Students divide into groups, with each group including a student presenting each proposal. Students will take less than 3 minutes to present their assigned proposal to the other group members, noting the impacts on the carbon cycle. Each group should also start to evaluate each proposal's broader impacts, using the grid below as a template to help guide the discussion. You should print one template for each proposal.

Small-group discussion template (Word)

SmallGroupTemplateWORD (Microsoft Word 2007 (.docx) 30kB Nov21 14)

Small-group discussion template (PDF)

SmallGroupTemplatePDF (Acrobat (PDF) 105kB Nov21 14)

When evaluating societal impacts, students should be encouraged to think about far-reaching implications associated with each proposal, including how each proposal would affect local, regional, and global communities; who within these communities would be affected; economic requirements and impacts; health concerns; and moral implications. Groups should be ready to discuss their findings during the next stage of this exercise, which is a whole-class discussion.

As a form of formative assessment, we encourage the instructor to walk around the room and briefly check in with each group to correct any errant notions and ensure that students are on track.

Whole group: (20 min)

The instructor facilitates a class-wide discussion of each proposal, asking groups to share their thoughts and findings and guiding students to highlight the broader implications of pursuing each proposal (i.e., addressing the societal, logistical, economic, and moral implications).

To conclude this portion of the activity, the instructor will have the class serve as voting members to a fictitious governmental panel tasked with either supporting or rejecting each proposal. Each member of the class will vote either "yea" or "nay" to recommend enacting each proposal, and the instructor or a student can keep count of the votes. We recommend using the discussion time as an opportunity to 1) explore each proposal's broader issues and 2) help students settle on their ultimate opinion for each proposal.

In order to help facilitate this discussion, instructors may also consider posing the following questions:

  • What are the economic and non-economic costs of pursing this proposal?
  • Who and what would be affected, and to what degree?
  • Is the proposal presented by a credible or unbiased organization? What conflicts of interest may be at work?
  • Is the proposal likely to succeed? Why or why not?
  • What resources are necessary? Are these reasonable?
  • What are the types of timescales involved with this proposal? Are the proposed actions consistent with these timescales?
  • What impacts would this proposal have in 10 years? 1000 years? 10,000 years? 1 million years?

Teaching Notes and Tips

Depending on how much time is available, the instructor may begin this activity with a review of the carbon cycle (Unit 2 of this module). In addition, we feel that it may be fruitful to explore the notion of "costs" associated with any certain decision, realizing that the term "cost" may extend beyond strictly economic parameters. For example, in very simplified terms, one cost of not studying for a test is that you may fail the exam.

It should be noted that each proposal has been offered as a viable course of action. There are serious merits and drawbacks to each, which is why we feel that they serve as suitable topics for discussion. Depending on class dynamics, the instructor may need to be aware that students' personal opinions could be rather strong. In these cases, it could be valuable for the instructor to stress that the class discussion should be supported by facts and that, in many cases, there is no "right" or "wrong" solution.

One possible extension from these topics could be a class debate. Students could be assigned a proposal and provided time at home to explore the pros and cons of pursing their proposal. In class, they can be assigned to support or refute the proposal and with a few other class members debate their position with the opposing view.


Formative Assessment:

The instructor should interact with students during the small-group discussion part of this exercise. These interactions should quickly evaluate the correctness of the carbon reservoirs involved, determine students' general understanding of the proposals, and help facilitate discussing the broader impacts of a proposal, as necessary.

Summative Assessment:

Concluding the whole-class discussion, and during the remainder of class, students will choose one of the proposals discussed and write a one- to two-paragraph statement of support or dissent for that proposal. This statement must include their own personal opinion and be well supported with facts and evidence. This statement should draw on multiple lines of evidence supporting the student's position, and as such, could be used to provide the instructor with a comprehensive sense of what the student has learned throughout this module. The rubric can be modified to include more categories, if desired.

We recommend that this assessment is also used to evaluate student learning for the entire module. In this case, the instructor should consider assigning the essay for homework to provide more time for students.

Summative Assessment Essay (Word)

Unit 6 summative assessment (Microsoft Word 2007 (.docx) 38kB Aug17 16)

Summative Assessment Essay (PDF)

Unit 6 Summative Assessment PDF (Acrobat (PDF) 75kB Aug17 16)

Summative Assessment Essay Rubric (WORD)

SummativeAssessmentRubricWORD (Microsoft Word 2007 (.docx) 34kB Aug17 16)

Summative Assessment Essay Rubric (PDF)

SummativeAssessmentRubricPDF (Acrobat (PDF) 54kB Aug17 16)

References and Resources

For more detail about jigsaw exercises, see Jigsaws, by Barbara Tewksbury, from On the Cutting Edge

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These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
Explore the Collection »