1. Human Energy Systems Unit Activity 4.3: The Seasonal Cycle Carbon: Transformations in Matter and Energy Environmental Literacy Project Michigan State University

2. The Keeling Curve 2 Explaining the seasonal cycle

3. 3 Watch a video about seasonal changes Amount of plant growth

4. How does this help explain the Keeling Curve seasonal cycle? 4 FebruaryJuly

5. Why do carbon dioxide concentrations GO DOWN during the spring and summer? 5 Let's use carbon transforming processes--photosynthesis and cellular respiration--and global carbon pools to explain.

6. Make predictions 6 Atmosphere Inorganic Carbon Pool Fossil Fuels Organic Carbon Pool Soil Organic Carbon Pool Biomass Organic Carbon Pool Atmosphere Soil Carbon Fossil Fuels

7. Instructions 7 Begin at one pool. On the poster, write your ideas about 1.where carbon atoms could go after they are in this pool, and 2.what causes them to go there. For example, if you are in the biomass pool, you might write “carbon goes to soil pool” because “leaves fall off a tree.” Write down as many ideas as you can think of (it’s ok if they are wrong). Then, move to the next poster. Revise and edit the ideas in the next pool. Keep moving until you return to your original pool.

8. 8 Soil Carbon Atmosphere Fossil Fuels Biomass 800 400 1000 790780770760750740730720710700690680670660650640630620610600590580570560550540530520510500490480470460450440430420410400 410420430440450460470480490500510520530540550560570580590600610620630640650660670680690700710720730740750760770780790800 990980970960950940930920910900 Fluxes of carbon change during seasons SPRING & SUMMER: Plants are growing Lots of photosynthesis Plants do photosynthesis and grow!! Plants and animals do cellular respiration. Decomposers do cellular respiration. Photosynthesis moves carbon atoms from the atmosphere to biomass. Cellular respiration moves carbon atoms from biomass to the atmosphere. Cellular respiration moves carbon atoms from soil organic carbon to the atmosphere. Death and defecation move carbon atoms from biomass to soil organic carbon Living things die and begin to decompose. 390380 810820 10101020

9. 9 Compare: What is the overall movement of carbon atoms among pools during the spring and summer? Beginning of spring (April)End of summer (October) Soil Carbon Atmosphere Fossil Fuels Biomass 800 400 1000 Soil Carbon Atmosphere Fossil Fuels Biomass 900 600 700

10. Why do carbon dioxide concentrations INCREASE during the fall and winter? 10 Let's use carbon transforming processes--cellular respiration--and global carbon pools to explain.

11. 11 Soil Carbon Atmosphere Fossil Fuels Biomass 800 400 1000 790780770760750740730720710700690680670660650640630620610600 410420430440450460470480490500510520530540550560570580590600610620630640650660670680690700 990980970960950940930920910900 Fluxes of carbon change during seasons Leaves fall and annual plants die and enter the soil pool. FALL & WINTER: Most plants stop growing Less photosynthesis 1010102010301040105010601070108010901100 Living things die and begin to decompose. Plants and animals still do cellular respiration. Cellular respiration moves carbon atoms from biomass to the atmosphere. Death and defecation move carbon atoms from biomass to soil organic carbon Cellular respiration moves carbon atoms from soil organic carbon to the atmosphere.

12. Soil Carbon Atmosphere Fossil Fuels Biomass 600 700 900 12 Compare: What is the overall movement of carbon atoms among pools during the fall and winter? Beginning of fall (October)End of winter (April) Soil Carbon Atmosphere Fossil Fuels Biomass 800 400 1000

13. Three Questions at the Large-Scale 1.The Carbon Pools Question. Where are the carbon pools in our environment? 2.The Carbon Fluxes Question: How are carbon atoms moving among pools? 3.The Energy Question: How does energy flow through environmental systems? 13

14. Example Scenario Card Round 1: For each scenario, decide as a group what will happen to the organic and inorganic pools of carbon. It is summer in the northern hemisphere and annual flowers begin to grow. Winter comes and the annual plants die and are digested by decomposers. Round 2: Explain how energy is transformed in the scenarios above. 14