Carbon Sinks and Sources Like all of the essential elements that make life on the planet possible, carbon, in the form of carbon dioxide and methane, is continuously recycled on Earth. Have you ever wondered how this cycling works? Activity Time: Summary CO2 to the atmosphere are called Part I: 15 minutes Through questioning and carbon “sources”, while processes Part II: 15 minutes partnering, students gain an that absorb it are called carbon understanding of the complex “sinks”. Forests, soil, oceans, the Setting: system of carbon cycling that atmosphere, and fossil fuels are Classroom or outdoors works to balance the levels of important stores of carbon. Carbon carbon in our atmosphere. is constantly moving between Materials: these different stores, that act as • Class set of carbon sink and Objectives either “sinks” or “sources.” A sink source “Who Am I?” and absorbs more carbon than it gives Partner cards (see Black Students will: • Gain an understanding of how off, while a source emits more than Line Masters) it absorbs. The amount of carbon Not included carbon cycling occurs • Use questioning techniques in the atmosphere at any one time • Candle and matches depends on the balance that exists • Green potted plant to determine the differences between a carbon sink and a between the sinks and sources. • For Demo: red cabbage This system of sinks and sources to be boiled, 2 small glass carbon source • Discuss how humans can influ- operates all over the planet and is containers, white vinegar, known as the carbon cycle. 1 straw ence the amount of carbon in our atmosphere Grade Level: Natural sources of atmospheric CO include volcanoes, fires, Intermediate, middle school, Making Connections 2 decomposition, respiration, high school We all have a role to play in digestion and, under certain combating climate change. Subject Areas: conditions, oceans and fresh water However, the issue can seem so Biology, Ecology, Earth Science, bodies. The latter can release large huge and the solutions so daunting Geography, Physical Science, amounts of dissolved CO when that individual actions seem 2 Resource Science, Science and waters warm up or are disturbed by insignificant. It is important for Technology, Social Studies storms or tremors. students to understand that simple choices made every day can have Skills: Natural sinks for atmospheric CO profound impact in the mitigation 2 Compare and contrast, gather include photosynthesis, forests, of the effects of climate change. information, question oceans and freshwater bodies, fossil fuels and carbonate rocks. Group Size: Background 10+ Carbon dioxide (CO ) and it’s 2 Before the Industrial Revolution, Key Words: sister greenhouse gas, Methane the amount of carbon moving (CH ), are continually recycled Carbon, Carbon Cycle, 4 between trees, soil, oceans and Carbon Dioxide, Methane, on Earth. Processes that release the atmosphere was relatively Sink, Source Sinks & Sources Page Carbon Sinks and Sources balanced. The forests of the world several times a year. Other parts destruction in the atmosphere. are a big carbon sink however of the cycle, especially those Methane (CH4) forms when deforestation is reducing the involving the storage of carbon organic matter decomposes in size of this sink, allowing more as an underground mineral, may oxygen-poor environments, such carbon dioxide to remain in the take millions of years to complete. as marshes, rice paddies, or the atmosphere. Photosynthesis Human perturbations to the digestive systems of cattle. It also accounts for about half of the carbon cycle are impacting the comes from combustion (burning) carbon extracted from the maintenance of the concentration of carbon-based fuels. Each atmosphere. Photosynthesis of atmospheric carbon. This methane (CH4) molecule holds equation: 6 H2O (water) + 6 CO2 is leading to an increase in about 23 times more heat than + sunlight energy = C6H12 O6 the amount of carbon in the 1 molecule of carbon dioxide. (glucose) + 6 O2 (oxygen). Land atmosphere as humans produce Methane (CH4) is 23 times more plants take most of their carbon carbon dioxide and methane potent than carbon dioxide as a dioxide from the air around them far faster than the natural sinks greenhouse gas, but CO2 is much while aquatic plants in lakes, seas can absorb it. The extraction, more abundant than methane and oceans uses carbon dioxide processing and use of oil, gas and and the predicted growth rate is dissolved in water. Phytoplankton coal are the greatest contributors far greater. is one of these important plants to this carbon loading. as they produce up to 50% of the In addition to contributing atmospheric oxygen through Sources of methane (CH4) include significantly to carbon sources, photosynthesis. Other important natural sources like wetlands, human activities are also sinks are the worlds oceans. The gas hydrates in the ocean floor, interfering with natural carbon world’s oceans are absorbing an permafrost, termites, oceans, sinks. For example, the clearing of unprecedented amount of carbon freshwater bodies, and non- tropical rainforests for agriculture dioxide (CO2), which is increasing wetland soils. Fossil fuels, cattle, and logging represents a their acidity and possibly landfills and rice paddies are the significant loss to the earth’s threatening the long-term main human-related sources. All ability to absorb and store carbon. survival of many marine species, these sources cause significant especially calcifying organisms carbon emissions. Methane including corals, shellfish and (CH4) is an important trace gas in Procedure phytoplankton (UNESCO, 2004). Earth’s atmosphere. Even though See demo activity in Warm Up it only makes up 0.00017% (1.7 Warm Up section to illustrate this point. parts per million by volume) of Light the candle and ask students the atmosphere, methane (CH ) 4 what they observe – candle, wick, The cycling of carbon between traps a significant amount of heat, flame. What is burning here – the the atmosphere, plants and helping the planet remain warm wick or the wax or both? Where animals can take place quickly, and habitable. The amount of do they go when they are burned? over the space of days or weeks. methane (CH ) in the atmosphere 4 Do they just disappear forever? Individual carbon atoms may is the result of a balance between Blow out the candle. cycle through plants and animals production on the surface and Sinks & Sources Page Carbon Sinks and Sources juice. What is the meaning of the juice changing colour? Debrief. When dissolved in water, CO2 com- bines with water to form carbonic acid H2CO3. This is a weak unstable acid. However, if concentrated enough this acid will over time dis- solve the calcium shell of marine organisms. Driving too much could literally kill the Great Barrier Reef. The Activity Part I . Draw a quick illustration of the carbon cycle on the board. Give a brief definition of sinks and sources. • Processes that release CO2 to the atmosphere are called carbon sources. • Processes that absorb CO2 are Demo Activity periment. Plastic is a petro- called carbon sinks. This experiment shows the leum product. Its production process is a source of carbon . Ask students for examples of acidifying effect of CO2 . Make an organic, non-toxic pH indicator by emission and it doesn’t processes that release CO2 to the boiling red cabbage. decompose.) atmosphere - carbon sources. 4. Slowly pour white vinegar List the sources on the board 1. Boil cabbage in a covered in one of the containers. Ob- • Point to the candle pan for 30 minutes or mi- serve the change in colour. • Us - we breathe out CO2 – we crowave for 10 minutes. (Do 5. Then, ask a student to blow are carbon sources along not let the water boil away.) through a straw in the with all air-breathing organ- 2. Let cool before removing the other container. Eventually isms cabbage. the cabbage juice will turn • Volcanoes 3. Pour about 1/4 cup of colour. • Fires cabbage juice into 2 see • Oceans and fresh water bodies through containers. (Avoid Ask student what he or she is (CO2 dissolves easily in water) buying plastic for this ex- breathing out into the cabbage • Agriculture - grazing animals Sinks & Sources Page Carbon Sinks and Sources (cows, sheep, pigs) produce green plants in storage), grow- carbon sink or a carbon source. methane ing forests: photosynthesis They will not know which they are • Burning fossil fuels – gas equation 6 H2O (water) + 6 CO2 but will have to figure it out by energy plants, coal, oil, gas, tar + sunlight energy = C6H12 O6 asking questions that can be an- sands (glucose) + 6 O2 (oxygen) swered only by yes or no. Note: it • Fossil fuel production: coals, glucose = carbon storage. may be necessary to demonstrate oil gas, tar sands – including • Diatoms, algae what yes/no questions sound like. the burning of natural gas • Fossilized organic remains be- during oil extraction (water, oil come fossil fuels like coal, oil 6. Hang a card on each student’s and gas mix) and the escape of and gas stored safely back so the wearer cannot see it. methane (CH4) during extrac- underground Participants must circulate and ask tion and processing of oil, gas • Oceans can absorb CO2 di- others just one Yes or No question and coal. rectly from the atmosphere. to determine what they are. They • Decomposing garbage in CO2 will stay in storage for a then must move onto another landfills/ dumps (methane) long time provided oceans person, show the card and ask a • Rice farms (produce methane) stay cool and undisturbed. The question. Students should repeat • Degrading farm soils: release carbon hydrate is in the slurry until they have determined what of carbon from soils when at the bottom in the form of they are. plowed sediments - causes it to oxidize creating • Shells, coral 7.