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The Carbon Cycle: Sources and Sinks

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The Carbon Cycle: Sources and Sinks Climate Science Lesson 4 Subject/Target Grade Science Middle School and High School The Carbon Cycle: Duration One 40 minute period – Classroom setting Sources and Sinks Materials From MEECS Climate Change Resource DVD • Carbon Cycle (QuickTime Movie – 2:22 minutes) Lesson Overview • Keeping Up with Carbon (MP4Video – 5:30 minutes) Students examine the carbon cycle,Only and identify sources • The Carbon Cycle (PowerPoint) and sinks within the environment. Students relate this information to greenhouse gas emissions of carbon dioxide per class in the context of greenhouse gas emissions in Michigan. • Carbon Cycle (transparency master) • Explore the Carbon Cycle (answer key) • Michigan Land, Air, and Water (answer key) Students will answer these essential questions: per group What is the Carbon Cycle? How do human actions • Michigan Land, Air, and Water (poster) (in Michigan) affect the Carbon Cycle? per student • Explore the Carbon Cycle (student activity) • Michigan Land, Air, and Water Objectives (student activity) Students will be able to: 1. Trace movement of atoms through the carbon cycle. 2. Identify carbon sources and sinks. 3. Explain how human activities release carbon into the atmosphere. Michigan Grade Level Content Preview Advance Preparation Expectations 1. If using the PowerPoint for this lesson, review to check Grade 6-7 Science: formatting on your computer. It might be necessary • Describe the origins of pollution in the to change font or font size to appear correctly on atmosphere, geosphere, and hydrosphere your computer. To use as a classroom presentation, (car exhaust, industrial emissions, acid rain and natural sources) and how pollution appropriate slide numbers are indicated in parentheses impacts habitats, climatic change, threatens under Procedures. or endangers species. E.ES.07.42 2. Set up videos from the MEECS Climate Change For(continued on next page) Resource DVD. 3. Make copies of Explore the Carbon Cycle and Michigan Land, Air and Water (student activity sheets). Michigan Environmental Education Curriculum Support Lesson 4 Climate Science 59 Lesson 4 Climate Science 4. Prepare Carbon Cycle transparency master (or use PowerPoint slide). Michigan Grade Level Content Expectations (continued) HS Earth Science: • Explain how carbon exists in different forms such as limestone (rock), carbon Background Information dioxide (gas), carbonic acid (water), and Carbon is exchanged, or “cycled” among Earth’s animals (life) within Earth systems and how those forms can be beneficial or oceans, atmosphere, ecosystem, and geosphere. harmful to humans. E2.3A All living organisms are built of carbon compounds. • Explain how carbon moves through the It is the fundamental building block of life and an Earth system (including the geosphere) important component of many chemical processes. and how it may benefit (e.g., improve soils for agriculture) or harm (e.g., act as a It is present in the atmosphere primarily as carbon pollutant) society. E2.3d dioxide (CO2), but also as other less abundant but • Compare and contrast the heat-trapping climatically significant gases,Only such as methane mechanisms of the major greenhouse gases resulting from emissions (carbon (CH4). dioxide, methane, nitrous oxide, fluorocarbons) as well as their abundance Because life processes are fueled by carbon and heat- trapping capacity. E5.4g compounds which are oxidized to CO2, the latter Climate Literacy Principles is exhaled by all animals and plants. Conversely, CO is assimilated by plants during photosynthesis • #2. Climate is regulated by complex 2 interactions among components of the to build new carbon compounds. CO2 is produced earth system. by the burning of fossil fuels, which derive from • #3. Life on earth depends on, is shaped the preserved products of ancient photosynthesis. by, and affects climate. The atmosphere exchanges CO continuously with • #4. Climate varies over space and time 2 through both natural and manmade the oceans. Regions or processes that predominately processes. produce CO2 are called sources of atmospheric CO2, while those that absorb CO2 are called sinks. Most of Earth’s carbon—about 65,500 billion metric tons—is stored in rocks. The rest is in the ocean, atmosphere, plants, soil, and fossil fuels. PreviewForests, oceans, and soil are the main carbon sinks on Earth. Carbon flows between each reservoir in the exchange called the carbon cycle, which has slow and fast components. Through a series of chemical reactions and tectonic activity, carbon takes 100-200 million years to move between rocks, soil, ocean, and atmosphere in the slow carbon cycle. On average, 1013 to 1014 grams (10–100 For million metric tons) of carbon move through the slow carbon cycle every year. In comparison, the fast carbon cycle moves 1016 to 1017 grams of carbon per year. Plants and phytoplankton are the main components of the fast carbon cycle. 60 Climate Science Lesson 4 Michigan Environmental Education Curriculum Support Climate Science Lesson 4 Human actions cause emissions of carbon to the atmosphere, at about 1015 grams of carbon per year. Note: The nitrogen cycle and the The atmosphere now contains more carbon than at halocarbon cycle (linked with the ozone any time in at least two million years, due to carbon cycle) are also natural parts of the complex moved from deep in the earth into the atmosphere. human influence on the environment. So far, land plants and the ocean have taken up about 55 percent of the extra carbon human actions have put into the atmosphere while about 45 percent has stayed in the atmosphere. Eventually, the land and oceans will take up most of the extra carbon dioxide, but as much as 20 percent may remain in the atmosphere for many thousands of years. Only solar energy releasing heat through the process Procedure of respiration. Plant life that decays or is burned also releases carbon dioxide, water vapor and energy. This is a natural and integral part of the earth’s environmental system. Note: The Keeping Up with Carbon video (found on the Climate Change Show the NASA video Carbon Cycle on the Resource DVD) reviews previous lessons MEECS Climate Change Resource DVD. and is a good introduction to this lesson. Discuss the main points: It can also be used at the end of this lesson • Carbon is exchanged between the oceans, as a review. solid earth, biosphere and atmosphere through various natural processes. (Slide 2) – What two processes between the 1. Dynamics of the carbon cycle. biosphere and the atmosphere cause the largest exchanges? Where does carbon dioxide in the atmosphere (photosynthesis and decomposition) come from and where it does it go? • For thousands of years, the processes that Preview added and subtracted carbon dioxide from The general formula for photosynthesis is: the atmosphere were in balance. (Slide 3) – Are they in balance now? (no) What does the video give as 6CO2 + 6H2O + sunlight = C6H12O6 + 6O2 – (photosynthesis) the reason for the imbalance? (dependence on fossil fuels) How does this cause the imbalance? C6H12O6 + 6O2 = 6CO2 + 6H2O + Heat – (respiration or burning) (When we burn fossil fuels for heat, For transportation, and electricity, large quantities of carbon that would Plants absorb CO2 and water, and through the process of photosynthesis produce large carbon otherwise remain stored in the solid molecules (sugar, wood, plants). Animals, earth are released into the atmosphere including humans, eat plants and use the stored in the form of carbon dioxide) Michigan Environmental Education Curriculum Support Lesson 4 Climate Science 61 Lesson 4 Climate Science 2. Explore the carbon cycle. 3. The Carbon Cycle in Michigan. The atmosphere exchanges CO2 continuously Give students a laminated copy of Michigan’s with the oceans. Regions or processes that Land, Air, and Water poster. (Slide 6) In small predominately produce CO2 are called sources groups students circle as many land-use sources of atmospheric CO2, while those that absorb CO2 of greenhouse gases as they can find pictured on are called sinks. (Slide 4) the poster. Chart these with type of greenhouse gas (carbon dioxide, methane, nitrous oxide, Show students the Carbon Cycle transparency other), and the process that produces the gas master. (Slide 5) Have students point out (respiration, burning, etc.) on the Michigan’s the carbon dioxide sources (where carbon is Land, Air, and Water student activity sheet. released) and sinks (where carbon is absorbed or stored). Use the Explore the Carbon Cycle student Only activity to categorize the sources and sinks for carbon dioxide. Students should be encouraged to explain their reasons for choosing source or sink. Assessment Options 2. Have students play the interactive online Carbon 1. The Explore the Carbon Cycle and Michigan’s Cycle game at http://www.windows2universe. Land, Air, and Water student activities can be org/earth/climate/carbon_cycle.html and answer used as assessment. the questions. The game board highlights the carbon reservoirs or carbon pools (atmosphere, plants, soils, shallow ocean, deep ocean, and marine life). They can follow up with a narrative of their carbon cycle journey. Adaptations/Extensions/ 2. Nature’s Recycling! Part B in the MEECS Enhancements PreviewEcosystem and Biodiversity Lesson investigates 1. Carbon Connections is a three-unit, online the role of plants in the carbon cycle. curriculum for grades 9-12 that was designed to improve understanding of the carbon cycle 3. Have students explore the potential of carbon and the science of Earth’s climate. Each of the sequestration in Michigan. Carbon sequestration three units includes five lessons. Each lesson is the term used to describe a broad class of includes focus questions, hands-on activities, technologies for capturing and permanently virtual field trips, and interactive models. The sequestering, or storing, CO2. The Midwest concepts coveredFor in the lessons span all science Regional Carbon Sequestration Partnership disciplines. Retrieved March 18, 2013 from website includes a variety of fact sheets and http://carbonconnections.bscs.org/ briefings on the topic with Michigan-specific information.
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