The Carbon Cycle: What Goes Around, Comes Around

Part B: Carbon In, Carbon Out: Reservoirs and Processes in the Global Carbon Cycle

In Part A, you examined how carbon moves through a forest carbon cycle. In this activity, you will explore the larger, more complex global carbon cycle using an interactive diagram developed by the University of Waikato in New Zealand. To access the carbon cycle interactive, click on the Carbon Cycle. When you click on the carbon cycle image in the new page, it will open up to the interactive.

Examine the carbon cycle interactive diagram with a partner. The key in the upper right-hand corner lets you distinguish between carbon reservoirs (carbon stores) and the processes that move carbon between reservoirs. The arrows represent carbon moving between reservoirs. Clicking on the topic boxes will give you background information on the processes and the reservoirs. As you click on the reservoirs, make note of the amount of carbon stored in these reservoirs and answer the checking-in question below.

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

Materials you will need are:

• Chart paper
• Pencils and colored pencils (red, blue, yellow, green)
  
• Post-it notes or cut blocks of paper + scotch tape (optional)
• Computer access to carbon cycle interactive
  

In this group activity, you will follow carbon's journey through one of the many carbon pathways within the global carbon cycle. Follow the five steps below and be prepared to present to the class or another group.

With your partner or group do the following:

1. Choose one of the following entry points for your carbon journey. You may choose to start out as a carbon atom stored in a reservoir(carbon store) or you may start out as a carbon atom already on the move in a process. Hint: Besides the arrows on the diagram, there are clues in the information pop-ups that may tell you where the carbon goes next.
   • Atmosphere
   • Coal, Oil, Gas
   • Decay/decomposition
   • Phytoplankton
   • Burning (wildfires)
   • Respiration
   • Vegetation
   • Carbon Dioxide exchange at sea surface
   • Soil and organic matter
   • Weathering and run-off
2. Determine a journey your carbon atoms will take, starting from your entry point. There are multiple carbon cycle pathways for you to choose from. For example, a carbon atom released from a tree may go through any one of the terrestrial pathways or one of the ocean pathways or both. You must choose a pathway that travels through at least three reservoirs.
3. Create a flow chart of your carbon's journey
• Identify the processes and reservoirs on your chart.
• Indicate the number of tonnes (metric tons)of carbon stored in the reservoirs on your flow chart, if available.
• Identify which Earth-system component the reservoirs are in.
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 slow time scale." If the information is available, indicate a time scale for movement of carbon between the reservoirs. You may use these designations and colors:
   
   • Very Fast (carbon atoms move between these reservoirs in less than a year ) - red arrow
     
   • Fast ( carbon atoms move between these reservoirs between 1- 10 years)- yellow arrow
     
   • Slow (carbon atoms move between these reservoirs between 10 to 100s years) - green arrow
     
   • Very Slow ( carbon atoms move between these reservoirs more than a thousands of years to millions of years) - blue arrow

5. Prepare for your 5 minute presentation to the rest of the class. In your presentation, you will need to do the following:
   • Describe the journey through the reservoirs and processes.
   • 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 carbon compound such as a glucose sugar, a carbonate or a hydrocarbon.
   • What organisms are involved (if any) and what is their role in the carbon cycle?
   • What kinds of chemical changes does your carbon go through on its journey through the carbon cycle.
   • How long does the carbon stay in the reservoirs? What are the time scales for carbon moving from one reservoir to another?