CO2 Exchange Between Air and Sea - Instructor's Guide
Published February 16, 2020
After engaging with the Data Exploration a student will be able to:
Identify periods of CO2 equilibrium, disequilibrium, and positive and negative flux of CO2 in the ocean
Identify patterns in atmospheric and oceanic data
Draw connections between patterns in atmospheric and oceanic data and patterns in oceanic air-sea CO2 flux
Evaluate relative importance of causes of variation in air-sea CO2 flux and their variability in time and space
Context for Use
This exercise could be used in oceanography, biogeochemistry and earth system science courses at all levels, from high school to graduate school, depending on what aspects of the module are emphasized and how the module is scaffolded. For an introductory course, the activity could be used repeatedly throughout the semester as a challenge question that is revisited as new knowledge is gained, resulting in final conclusions by the end of the semester. For upper level courses such as a Physical Oceanography class, it might be a more stand-alone activity late in the semester, although students may still need to be reminded of some of the background knowledge required to piece the story together. For upper-level classes, this module may also be used as a springboard for discussion of geographic variation in carbon uptake and release by the ocean. Overall, this exploration emphasizes the crucial role of the ocean in Earth's carbon cycle and the double-edged sword that is the ocean?s ability to absorb carbon dioxide.
Invitation: As an introductory activity, you can:
Missing? carbon in the atmosphere
You've heard of ocean acidification; why is that happening?
Discuss what students have uncovered about the key variables that affect air-sea CO2 flux
Discuss mechanisms that explain how/why those variables actually physically change CO2 flux
Compare coasts; discuss role of upwelling?
(Part 2 of widget) Give students a set of similar data from an unknown site. Ask them to compare patterns in these data to patterns in the ?known? data to determine
Is this site a source or sink? What environmental factors cause this? (This question reinforces ideas learned during the Exploration and Concept Invention phases).
What region (East or West coast) is this site located in? (This question reinforces the idea that particular regions may be sources or sinks based on their environmental variables)
Using what they have learned in the Exploration phase, students could predict worldwide distribution of ocean sources or sinks. Depending on the level, you could either give students maps of temperature, windspeed, and primary production, or leave that up to them to remember.
Reflection: You could...
Ask students to consider where else in the world the ocean may be a source or sink, based on global variation in temperature, windspeed, etc.
Ask students to evaluate the impact of climate change on whether the ocean will continue to be a sink, become less of a sink, or become a source.
Subject / Topics
Ocean geography: how and why temperature and other properties differ within and across ocean basins.
Water chemistry: dissolved gases, gas solubility
Air-sea gas exchange: concept of flux (mass per unit area per unit time). How flux is dependent on wind speed, ocean-atmosphere concentration differences, and gas solubility
Primary production: impacts on ocean undersaturation/supersaturation of CO2 and O2
Carbon cycle: oceans as a globally significant sink and source of CO2, but overall a net sink under current conditions.
Climate change: oceans take up half of the CO2 humans have emitted to the atmosphere.
Ocean acidification: but the uptake of the CO2 comes at a cost-- namely, ocean acidification.
It requires taking information in one form, mostly graphs, and conceptualizing about the Oregon continental shelf.
Primarily intended for the advanced undergraduate level, but could be used in advanced (11/12) high school courses, introductory undergraduate courses, or at the graduate level depending on how it is scaffolded and what aspects of the module are emphasized. In introductory classes, instructors may want to have students grapple with one or a couple of the concepts and fill in the details for them on the rest. In more advanced classes students should be challenged to recall previously learned information and apply it to this problem. Instructors should be ready to jog their memories about the learned information.
Mostly reading graphs, searching for patterns and correlations