Initial Publication Date: July 7, 2011 | Reviewed: October 14, 2015

Carbon on the Move!

Part B: The Global Carbon Cycle

In Part A, you investigated how carbon moves through a forest carbon cycle. In this section, you will use a global Carbon Cycle interactive to investigate carbon's many pathways through the larger, more complex global carbon cycle. Understanding how carbon moves between land, oceans and atmosphere is key to understanding how our climate will continue to change. Before you begin using the interactive, watch the NASA video below "Keeping Up with Carbon." As you watch, make note of the role of the Biosphere in the global carbon cycle.

If the video does not play , watch here NASA | Earth Science Week: Keeping Up With Carbon - YouTube or on Vimeo Follow carbon through the global Carbon Cycle

Before you begin the global carbon cycle activity below, become familiar with the "The Carbon Cycle" interactive by clicking the orange and purple rollover buttons and making note of the different types of background information that pop-up. You will be using important information in the pop-up windows to identify and describe two different carbon pathways through the global carbon cycle. Here are some hints to help you use the interactive:

  • The key in the upper right-hand corner lets you distinguish between carbon reservoirs and the carbon cycle processes. Orange buttons are carbon cycle processes; purple buttons are carbon cycle reservoirs.
  • The arrows represent processes that are moving carbon atoms from one reservoir to another reservoir.
  • As you investigate reservoir pop-up windows, think about whether a reservoir is in the Biosphere or the Geosphere. Also, think about whether a process is a Biosphere process or a Geosphere process.

The Carbon Cycle TERC, informmotion

*This video replaces a Flash interactive. Play, pause, and replay the video as necessary to view the reservoir pop-ups you need.

To view this interactive on an iPad, use this link to download/open the free TERC EarthLabs App.

Now that you are familiar with using the carbon cycle interactive, you are ready to start the global carbon cycle activity.

Global carbon pathways

In this group activity, you will identify and describe two different carbon pathways that carbon can take through the global carbon cycle. Here are four general rules you must follow:

  • You must start in a reservoir of your choice and identify a complete carbon pathway that takes you back to the same reservoir.
  • At least one of your two carbon pathways must go through part of the ocean.
  • One of the two carbon pathways must illustrate a fast carbon cycle. (Note: Fast carbon cycle pathways are completed in short timescales of minutes up to several hundred years.)
  • The other carbon pathway must illustrate a slow carbon cycle. Slow carbon cycle pathways are completed in long time scales of thousands of years to millions of years

With your partner or group, follow the steps below for each of your two carbon pathways. Be prepared to present your fast and slow carbon pathways to the class or another group.

  1. Choose a carbon reservoir to start your carbon pathway.
  2. Determine a pathway your carbon atoms will take, starting from your entry point reservoir. There are multiple carbon cycle pathways for you to choose from. Hint: In addition to the arrows on the interactive diagram, there are clues in the pop-up tabs that may tell you where the carbon can go to next.
  3. Create a flow chart for each carbon pathway. Your charts should include the following information:
    • Names of the reservoirs the carbon moves through;
    • Arrows indicating the processes that move carbon between reservoirs. Label each process;
    • Label each reservoir as belonging to the Biosphere or Geosphere;
    • Gigatons (GT) of carbon stored in the reservoirs if available;
    • Forms of carbon compounds found in each reservoir and indicate whether each is a solid(s), liquid(l) or gas(g). (examples: carbohydrate(s), calcium carbonate(s), CO2 (g))
  4. As you draw your arrows between the reservoirs, think about about how long it takes for these carbon atoms to move from one reservoir to another. For example, a carbon atom can stay in sedimentary rocks for millions of years before moving to a different carbon reservoir. This would be an example of a "very long and slow time scale." If the information is available, indicate a time scale for movement of carbon from one reservoir to the next reservoir.
  5. Using your flow charts for your two carbon pathways, give a 5-minute presentation to the rest of the class. In your presentation, you will need to do the following:
    • Describe your two carbon pathways through the reservoirs and processes. What processes move the carbon out of one reservoir into another?
    • Does the carbon change from one type of carbon compound to another when it moves between reservoirs? For example, it may start off as a gas and change to a solid, or carbon may be present in one reservoir as carbon dioxide but in another reservoir may be a complex organic carbon compound such as carbohydrate sugar.
    • What living organisms are involved (if any) and what is their role in moving and storing the carbon in the two pathways you have chosen? Describe any small organism(s) that has a big role in in moving and storing carbon. What organism(s) strongly influence the amount of CO2 in the atmosphere? Describe any small organism(s) that has a big influence
    • How long does the carbon stay in each reservoir? What are the time scales for carbon moving from one reservoir to another?
    • Explain why your carbon pathway belongs to a slow carbon cycle or a fast carbon cycle.


After your presentations, discuss the following with the class:

  • In the global carbon cycle, does carbon move at faster time scales through the Biosphere or through the Geosphere? Why do you think this occurs?
  • Which carbon pathway(s) has the greatest potential to warm our climate further? Why?
  • Many countries are cutting down forests to make way for agriculture and roads. How might this practice disrupt the carbon cycle? What reservoirs and processes might be impacted? Why?
  • The world's population has passed the 7 billion mark. As the population continues to increase, the need for energy will also increase. How might the increased need for energy impact the global carbon cycle? Why?

Optional Extensions

Want to learn more about the global carbon cycle. Check out these resources below:

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