Unit 6: Ocean Sustainability and Geoengineering
- Apply knowledge of the carbon cycle and food web dynamics to explain the conceptual approach that geoengineering strategies (i.e. ocean fertilization) are built on.
- Analyze the pros and cons of implementing geoengineering solutions to address changes to the global climate system.
This unit directly supports multiple InTeGrate guiding principles and addresses grand challenges by evoking systems thinking based on previously acquired knowledge (Units 1 through 5). They will be able to interpret and discuss media reports related to geoengineering questions and identify bias and/or error in light of political or economical reasoning.
Context for Use
This unit should be used in connection with the previous units of the Ocean Sustainability Module for an introductory marine, environmental, or geoscience course. This unit is designed to be used in a classroom of 10–100 students over the course of one 50-minute class period. Work is completed in class and is followed by homework (accumulative assessment) to design a fact sheet on global climate change impacts on marine communities and discuss mitigation strategies.
Description and Teaching Materials
1. Lecture and classroom discussion (10 min)
Instructor starts with first part that engages the students (open question and answer format) in a review of previous units on the carbon cycle, ocean currents and biological productivity, organismal diversity, and food web dynamics.
Lecture for instructor (with answer slides) —
Lecture for students (without answer slides) — Unit6_LectureStudents (PowerPoint 2007 (.pptx) 2.8MB Oct27 16)
Notes on Lecture (see details in comment section in PowerPoint):
- Slides 1 and 2 — Learning goals, definition of geoengineering, lecture content.
- Slides 3 and 4 — Review of Unit 1 on temperature, ocean currents and productivity. Students provide answers on "direction of water" and patterns of "nutrient availability."
- Slides 5 and 6 — Review of Unit 2 on the carbon cycle, which was discussed with an emphasis on the solubility cycle previously and now focuses on how biologically-driven processes impact the carbon cycle. Students provide answers on the missing terms.
- Slide 7 — Concept chart summarized how abiotic factors such as temperature and carbon chemistry interact with biological processes and revisits examples previously discussed. The missing terms are filled in by the students in Activity 6.1 (below).
2. Activity 6.1 (8 min)
Students use the provided list of terms to fill in the missing processes (arrows) and organisms (circles) in the concept map. Allow students to compare and discuss with their neighbors. Continue lecture by showing the filled in concept map and answer any emerging questions. — Slide 8.
- Activity 6.1 Handout (Acrobat (PDF) 383kB Oct22 16) Activity 6.1 Handout (Microsoft Word 2007 (.docx) 147kB Nov6 16)
3. Activity 6.1 Follow-up (10 min)
Building on the review, the instructor will explain how biological processes within the water column can lead to the sequestration of CO2 and subsequent transport of organic matter to the deep ocean (biological pump), and how this process has become the basis for geoengineering strategies (e.g. ocean fertilization). Students are introduced to several strategies of geoengineering and will be able to exemplify the challenges and risks that arise using the example of ocean fertilization.
- Slides 9 –13 — Walk students through the carbon cycle by separately discussing processes that drive the conversion and fate of biological carbon in the upper and then the lower water column.
- Slides 14 and 15 — Introduce students to ocean surface regions that are characterized by high nutrient but low productivity, where micronutrients limit phytoplankton growth, and the idea of ocean fertilization as a means to increase algal growth and subsequent CO2 sequestration and carbon transport to depth. Leads into Activity 6.2.
4. Activity 6.2 and (~8 min) Answer Discussion (15 min total)
Students individually familiarize themselves with the graphic illustration and background information on an iron fertilization experiment off the coast of Alaska. They then answer four related questions that require them to analyze the presented information in context with the lecture material. After the students hand in their filled-in activity sheets, the answers are discussed using the PowerPoint answer slides (14–18 in the instructor version of PowerPoint). There should be time for discussion of potential misconceptions or difficulties in interpreting the data. This activity will lead directly into the rest of the lecture.
- Activity 6.2 Handout (Acrobat (PDF) 292kB Oct28 16) Activity 6.2 Handout (Microsoft Word 2007 (.docx) 245kB Nov6 16)
5. Lecture Continued: Instructor discusses the answers to Activity 6.2 (5 min)
- Slides 17 through 19 — A finalized concept chart is shown that incorporates the use of small-scale (MPAs) and large-scale strategies (geoengineering) to preserve ocean ecosystem health and mitigate global warming. The chart also includes strategies of radiation management and carbon removal that can, but do not always, involve biological processes. Varying strategies are further illustrated in Slide 18. Finally, students are informed about how the status of the science (existing studies and reports) has been compiled by the National Research Council and led to general recommendations on climate intervention (Slide 19).
Teaching Notes and Tips
Final slide — Brief history of Iron Fertilization Hypothesis and John Martin's legacy, depending on whether instructor does want to go into more depth about the recent history of Iron Fertilization.
Lecture and Included Review: Students have to review previous lecture content on carbon cycling and biological processes to build their understanding of the biological pump and its premise as a geoengineering tool (Learning Goal 1).
Activity 6.1 and Class Discussion: Students will analyze the outcome of an iron fertilization experiment and are challenged to evaluate the success or failure of this experiment. By that they are building their understanding on why there are large uncertainties and risks in implementing geoengineering solutions to address changes to the global climate system (Learning Goal 2).
References and Resources
Articles and Resources
- The Guardian: Is geoengineering a bad idea?
- Woods Hole Oceanographic Institution, Oceanus Magazine: Fertilizing the Ocean with Iron Should we add iron to the sea to help reduce greenhouse gases in the air? by Hugh Powell
- NASA climate resources — Global climate quiz and related information pages
- EPA Local https://www.epa.gov/statelocalclimate/local-government-climate-and-energy-strategy-series
- Illegal Ocean Fertilization for Carbon Credits? with article, posted on The Huffington Post.