Unit 1: Ocean Circulation and Health
In this unit, students explore the role of ocean circulation in climate modification and bioproductivity. The activities require students to interpret the effect of horizontal and vertical seawater movement on heat distribution, carbon dioxide dissolution, and nutrient availability. Students will use their new knowledge to predict how those parameters may change as a result of major shifts in ocean circulation associated with global climate change.
By completing this unit, students will be able to:
- Describe how global ocean currents affect coastal net primary productivity and fishing industries.
- Predict how ocean currents might be affected by modern climate change.
- Formulate hypotheses about how regional parameters (climate, primary productivity) may change as a result of climate-driven change in ocean circulation.
This unit directly supports multiple InTeGrate guiding principles and addresses grand challenges by introducing students to how ocean circulation impacts both bioproductivity and climate feedbacks.
Context for Use
This unit is designed to be used during a 50-minute class period and is ideal for class sizes of 10–50, but can be used for any class size. For larger classes, individual groups should be larger, and discussion can remain in groups with a final class discussion at the end of the class period. It can be used as a stand-alone lesson in an introductory oceanography, environmental geology course or as part of the ocean sustainability module. Students should have some understanding of drivers behind ocean currents. If they do not, assign the following National Oceanic and Atmospheric Administration (NOAA) video as pre-homework: http://oceanservice.noaa.gov/facts/current.html.
Description and Teaching Materials
Students should watch NASA's Perpetual Ocean, accessible at https://www.youtube.com/watch?v=xusdWPuWAoU or https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3827.
Review pre-homework (5 min)
Begin by asking students if they know what drives the lateral ocean currents that they saw in the pre-homework assignment. Let them know that there are vertical currents we cannot see at the surface of the ocean, and that these can be controlled by lateral ocean currents. Provide the students with the handout and review reading (background) and instructions with them. Note: activities can be printed in grayscale or black and white.
Activity 1.1 Upwelling and downwelling (10 min total)
Activity 1.2. Upwelling, downwelling and bioproductivity (20 min total)
Activity 1.1 introduces students to basic ocean circulation and provides students an opportunity to determine what the primary controls on upwelling and downwelling of seawater.
5 min: Students should work individually on the Activity 1.1 Basic Rules of Ocean Circulation guided questions. During this time it is helpful to walk around the classroom to see if any students have questions.
5 min: Split students into groups of four and encourage them to compare their answers for Activity 1.1. — adjust the number of students in each group if there are an odd number of groups. During this time it is helpful to walk around the classroom to check that each group has correct answers.
In Activity 1.2, students are required to describe how surface currents can control where zones of high net bioproductivity occur.
5 min: Have groups count off in order from 1 to 16 and record their group number. If there are more than 16 groups, have them start over at 1 when 16 is reached. Either pass out maps or have students come up to collect a map for their group. Odd-numbered groups get a surface current map and even-numbered groups get a net primary productivity map. Instruct the groups to look at the chart in the handout to determine their assigned region.
5 min: Instruct groups to identify regions of diverging currents/upwelling (odd groups) or high net primary productivity (even groups) and mark these regions on their maps.10 min: Instruct students to compare their answers with another group that is assigned to the same region (they should use the table in the handout to find the group they should pair with. For examples, group 1 should find group 2; group 3 should find group 4, etc.). The students should also spend this time answering the remaining questions in Activity 1.2.
Activity 1.3. Effect of climate change on ocean circulation and health (15 min total)
Activity 1.3 allows students to predict global effects of climate change on ocean circulation and feedbacks to climate. Students should think about global effects on carbon dioxide uptake at the ocean surface and delivery to the deep ocean, and nutrient availability for bioproductivity.
5 min: Review the PowerPoint (PowerPoint 2007 (.pptx) 930kB Feb21 17) to provide background for the Earth system (notes are provided within presentation).
10 min: Instruct students to read the article and discuss their initial reactions with their group-mates. The reading and questions can be assigned as homework.
***Unit 1 Homework below can be used as an alternative for Activity 1.3 for those instructors who want to explore the effects of climate change on deep ocean circulation.
Activity files: *Note that Activities 1.1, 1.2 and 1.3 are meant to be classroom exercises, although Activity 1.3 could easily be assigned as homework if time is limited. The original Word files (.docs) were provided so that it is possible to make changes.
- NASA's Perpetual Ocean (MP4 Video 428.4MB Aug6 15)
- Activities 1.1-1.3 (.doc) (Microsoft Word 2007 (.docx) 485kB Nov4 16) | Activities 1.1-1.3 (.pdf) (Acrobat (PDF) 463kB Nov4 16)
- Activity 1.2_maps (.ppt) (PowerPoint 2007 (.pptx) 472kB Oct21 22) | Activity 1.2_maps (.pdf) (Acrobat (PDF) 401kB Oct21 22)
- Unit 1_homework (.doc) (Microsoft Word 2007 (.docx) 685kB Nov4 16) | Unit 1_homework (.pdf) (Acrobat (PDF) 625kB Nov4 16)
Teaching Notes and Tips
This unit requires quite a bit of group work. It is recommended that the professor start each activity with a short introduction. While groups are working, walk around the classroom to keep students on track. For Activity 1.1 it is helpful to review answers before students move on to Activity 1.2.
You can print the surface currents map in black and white or grayscale. The net primary productivity map should be printed in color—or, if color copies cannot be made, it should be projected for the even-numbered groups.
Assessments test whether students have a basic understanding of what drives vertical ocean currents (Activity 1.1) and how ocean currents affect net primary productivity (Activity 1.2). Activity 1.3 tests whether students can combine newly gained knowledge to outline how climate change is changing ocean circulation and bioproductivity.
References and Resources
- Oregon State Ocean Productivity Home Page
- Deep Ocean Current May Slow Due to Climate Change, Penn Research Finds, PennNews, March 20, 2014 [
- NASA Perpetual Ocean, NASA/Goddard Space Flight Center Scientific Visualization Studio, accessible at: https://www.youtube.com/watch?v=xusdWPuWAoU or https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3827