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Investigating whether man or mountain emits more atmospheric carbon dioxide Renee Clary and James Wandersee March 2015 23 Climate change to the forefront F IG UR E 1 Historic volcanic eruptions, such as this April 26, 1872, eruption of Mount Vesuvius in Italy, emitted large amounts of volcanic gases into the atmosphere, including CO2. Meanwhile, some climate-change skeptics suggested that volcanoes emit more CO2 than human activities. A volcano (Figure 1) can produce three phases of materials: solids (pyroclastics), liquids (magma/lava), and gases (water vapor, CO2, F IGUR E 2 Although we see vehicles polluting the atmosphere and cities blanketed by smog (left), students often have difficulty comprehending the additive effects of human activities on climate compared to large, dramatic natural events such as volcanic eruptions. COURTESY OF ZAKYSANT After the IPCC released its fourth assessment report in 2007, we saw the climate issue move to the forefront of media attention and classroom discussions of our students (Clary and Wandersee 2012a). In 2009 came “Climategate,” in which hacked e-mails from climate scientists at England’s University of East Anglia brought into question scientists’ impartiality and research ethics. Although later investigations exonerated the scientists of illegal behavior (Oxburgh 2010; Russell et al. 2010), members of the public remained skeptical (Leiserowitz et al. 2013). GIORGIO SOMMER, 1834–1914 I n 2013, the Intergovernmental Panel on Climate Change released its fifth report, attributing 95% of all climate warming—from the 1950s through today—to humans (IPCC 2013). Not only did the report—like previous IPCC reports dating back to 1990—accredit global warming to anthropogenic carbon dioxide emissions, but over time the vast majority of scientists have endorsed this view of human-caused climate change (Cook et al. 2013; Oreskes 2004). Still, we meet many students who question whether climate change is real, whether it is part of a natural cycle, and whether other sources besides humans may be responsible. To compare the role of natural Earth processes in CO2 emissions with humans’ role, we designed a student research investigation described in this article. Students graph volcanic and human components in CO2 emissions, analyze their results, and then can compare their results with those in peer-reviewed scientists’ reports. 24 The Science Teacher Finding the CO2 Culprit FI G U R E 3 COURTESY OF WOLFGANGBEYER Volcanic eruptions are powerful natural hazards that emit atmospheric greenhouse gases. But are their emissions as substantial as those caused by human activities, such as power generation (right)? and sulfur gases). The CO2 and other gases are emitted as the volcano’s magma degasses. How does the volcanic CO2 contribution compare to the anthropogenic one? Fortunately, a U.S. volcanologist calculated human and volcanic effect on CO2 production (Gerlach 2011). Summerhayes (2011), of Scott Polar Research Institute, furthered the investigation to find the source of greenhouse gases. Results of these investigations showed that modern volcanoes annually emit only as much CO2 as states like Florida, Michigan, or Ohio (Gerlach 2011). A student investigation Using data reported by Gerlach (2011) and Summerhayes (2011), from both direct monitoring and computer modeling, we designed a student investigation into the source of CO2, comparing volcanic emissions to those produced by human activity, and whether humans should accept the responsibility that the IPCC (2013) attributed to us. The graphical representation of authentic data augments the peer-reviewed articles we bring into the classroom and provides students with the “aha!” moment in their understanding of the issue. If needed, teachers can assess incoming student knowledge with a published Climate Change Survey (Clary and Wandersee 2012a, 2014). To begin the inquiry, we announce that students will investigate and compare two sources of CO2,, the greenhouse gas most implicated in global climate change. Beside water vapor, our atmosphere consists primarily of nitrogen (N2), at 78%, and oxygen (O2), at 21%. Carbon dioxide makes up only 0.04% of the atmosphere by volume yet is still the gas most associated with the greenhouse effect. (Often, CO2 levels are reported in parts per million [ppm]. Concentrations in ppm can be calculated by multiplying the percentage of volume by 104. That gives us a current concentration of atmospheric CO2 of approximately 400 ppm.) What are the sources of CO2? Undoubtedly, humans’ use of fossil fuels—for power generation, transportation, and other energy needs—contributes some of the greenhouse gas (Figure 2). However, at first glance, a powerful volcano can seem to have a more substantial CO2 contribution (Figure 3). Which source is greater? This is the driving question we pose to our students. This research activity may be done by individuals or small groups (2–3 students each). First, students need to retrieve the Global Fossil-Fuel CO2 Emissions from the Oak Ridge National Laboratory (Boden, Marland, and Andres 2013) (see “On the web”). Students should select the Global Digital Data, and we recommend the ASCII, comma-delimited format for easy import into a Microsoft Excel spreadsheet. (Teachers may need to provide a brief tutorial in how to use spreadsheets and computer-aided graphing.) Allow students to decide how much of the data they wish to use in their graphic analyses; Figure 4 (p. 26) briefly describes the categories. We used total carbon emissions from 1950 through 2010, because the 2013 IPCC report ascribed 95% of total emissions March 2015 25 FI G U R E 4 Examples from the categories of carbon emissions, Oak Ridge National Laboratory. Category Total carbon emissions Carbon emissions from gas fuel consumption Carbon emissions from liquid fuel consumption Carbon emissions from solid fuel consumption Carbon emissions from cement production Carbon emissions from gas flaring Examples Fossil fuels (petroleum, coal, methane etc.) and cement production Methane in power plants, heating, etc. Gasoline and diesel in power plants, vehicles, etc. Coal-generated power plants, etc. Release of CO2 from heating of CaCO3 Burning of light hydrocarbons at refineries, well heads, etc. from that time range to human activity. (In the downloaded spreadsheet, “Total carbon emissions from fossil fuels” is the second column.) Students should next investigate how these anthropogenic carbon dioxide emissions, from fossil fuels and cement production, compare with the naturally emitted CO2 from volcanoes. There are many estimates of volcanic emissions. When both submarine and subaerial volcanoes are included, the estimates range from 0.18 to 0.44 Gt (gigatons) per year; the accepted average is 0.26 Gt/year of CO2 (Gerlach 2011). We next ask students to include the 0.26 Gt CO2 average per year on their graphs, being careful to ensure that all units and components may be compared. Students should recognize that the Global Fossil-Fuel CO2 Emissions reports are in million metric tons of carbon, while the volcanic emission data are in gigatons of carbon dioxide. We include the conversion, below, for Gt CO2 to metric tons C that makes use of the fact that carbon atoms make up 12/44 of the mass of a carbon dioxide molecule. (The alternative is to convert all C emissions from the Global Fossil-Fuel CO2 Emissions reports from million tons C to Gt CO2.) 3 12g C 0.26 Gt CO2 x 10 million tons x = 71 million tons C 44g CO 2 1 Gt Students should plot their data for both anthropogenic and average volcanic contributions. The result is startling: The average volcanic contributions are minimal and stable. Even if we required students to plot annual differences in vol- FI G U R E 5 Sample graph of anthropogenic carbon (blue) and volcanic emission carbon (pink). Estimates of volcanic emissions range from 0.18 to 0.44 Gt (gigatons) per year. 26 The Science Teacher Finding the CO2 Culprit canic CO2 emitted, the scale of the graph would make these variations too small to be discernible. Therefore the volcanic CO2 contributions are stable over time. The human contributions, however, are noticeably rising (Figure 5 offers a sample graph). (Note: We recommend that teachers don’t disseminate conversions before students produce their graphs so that students have a chance to examine the analyses and results and determine how errors could have been made.) After classroom discussion and comparison of graphics, students/groups return to their graphs, correct them if necessary, and reflect upon the human and volcanic components in CO2 production. Students should address which component represents stability and which component affects (climate) change. The data analysis, graph, interpretation, and reflection can be assessed with a teacher-constructed rubric or extended into other activities. Teachers can also ask students to predict whether human sources of CO2 compared more equitably with volcanic sources before the industrial revolution. Students can return to the spreadsheets and graph CO2 emissions before 1800, 1800–1850, 1850–1900, and/or 1900–1950 for evidence of human impact on CO2 levels. Or students can predict which countries contribute most to CO2 emissions and graphically analyze whether their predictions were accurate. A list of CO2 emissions summarized by country is available online (see “On the web”). Extension of the CO2 culprit There are several options to extend an anthropogenic-versusnatural-CO2 investigation. Teachers may introduce (1) cataclysmic volcanic eruptions as exceptional producers of CO2; (2) comparison of student results with peer-reviewed research literature; and (3) student reflections on how their initial perceptions of CO2 production changed with this investigation and the influence of the media on their perceptions. Cataclysmic volcanism. Return to the data set and ask students to consider episodic large volcanic eruptions in their data set (Gerlach 2011). Students should include ◆◆ Mt. St. Helens, 1980, +0.01 Gt CO2 ◆◆ Mt. Pinatubo, 1991, +0.05 Gt CO2 Are the graphs significantly changed by cataclysmic eruptions? Because there is a large-scale difference between human CO2 input and volcanic CO2 emissions, students will discover that even large eruptions do not noticeably influence the stable volcanic contribution of total carbon dioxide gas. Comparison with published, peer-reviewed literature. Students can access Gerlach’s (2011) article online (see “References”) and compare their analyses and reflections against the conclusions in peer-reviewed literature. How did their interpretations align with a volcanologist’s interpretation? How did they differ? Gerlach’s article is readable and succinct and can be discussed in student groups and/or used for group presentations involving evidence-based argumentation. Over time, the average volcanic emissions of CO2 are minimal and stable. Media influences. Teachers can focus the next investigation on scientific practices and how scientists conduct and endorse climate change research. Singh’s blog, “How Do We Know Anything for Certain” (see “On the web”) includes links to relevant articles and a video comparing modern climate change discussions to past debate about cigarette smoking and lung cancer. Students can reflect on how the media affected their attitudes toward human-caused climate change and whether the CO2 Culprit activity changes their perceptions. CO2 investigations, Next Generation Science Standards, and the Common Core Our CO2 Culprit investigation lets students analyze realworld data and draw conclusions. The investigations can address several dimensions of the Next Generation Science Standards (NGSS Lead States 2013) (Figure 6, p. 28), HS-ESS-3 Earth and Human Activity, including crosscutting concepts such as Stability and Change and Cause and Effect (demonstrated by CO2 levels after the industrial revolution) along with the disciplinary core ideas such as ESS3.C: Human Impacts on Earth Systems. The investigations also align with elements of the Common Core (NGAC and CCSSO 2010). Conclusion Climate change is a prominent topic for our students, both within the classroom and outside of school. These young citizens need a thorough understanding of the issue so they can make informed decisions about the planet’s future. Our previous research indicated that sustained research and discussion increased understanding of the complexity of the March 2015 27 F IGU R E 6 Connections to the standards. Next Generation Science Standards. The materials/lessons/activities outlined in this article are just one step toward reaching the Performance Expectations listed below. Additional supporting materials/lessons/activities will be required. HS-ESS3 Earth and Human Activity Performance Expectations Students who demonstrate understanding can: HS-ESS3-1 Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity. [Clarification statement: Examples of natural hazards can be from interior processes (such as volcanic eruptions and earthquakes), surface processes (such as tsunamis, mass wasting and soil erosion), and severe weather (such as hurricanes, floods, and droughts).] HS-ESS3-6 Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity. Science and Engineering Practices Disciplinary Core Ideas Crosscutting Concepts Constructing Explanations and Designing Solutions Construct an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future. (HS-ESS3-1) ESS2.D: Weather and Climate • Current models predict that, although future regional climate changes will be complex and varied, average global temperatures will continue to rise. The outcomes predicted by global climate models strongly depend on the amounts of human-generated greenhouse gases added to the atmosphere each year and by the ways in which these gases are absorbed by the ocean and biosphere. (secondary to HS-ESS3-6) Cause and Effect Empirical evidence is required to differentiate between cause and correlation and make claims about specific causes and effects. (HS-ESS3- 1) Using Mathematics and Computational Thinking Use a computational representation of phenomena or design solutions to describe and/ or support claims and/or explanations. (HS-ESS3-6) Systems and System Models ESS3.B: Natural Hazards When investigating or • Natural hazards and other geologic events have shaped describing a system, the the course of human history. (HS-ESS3-1) boundaries and initial conditions of the system ESS3.C: Human Impacts on Earth Systems need to be defined and their • The sustainability of human societies and the inputs and outputs analyzed biodiversity that supports them requires responsible and described using models. management of natural resources. (HS-ESS3-6) ESS3.D: Global Climate Change Stability and Change • Through computer simulations and other studies, Change and rates of change important discoveries are still being made about how the ocean, the atmosphere, and the biosphere interact can be quantified and modeled over very short or and are modified in response to human activities. very long periods of time. (HS-ESS3-6) Some system changes are irreversible. Common Core State Standards. ELA/Literacy. RST.11-12.1 Cite specific textual evidence to support analysis of science and technical texts, attending to important distinctions the author makes and to any gaps or inconsistencies in the account. (HS-ESS3-1), (HS-ESS3-2), (HSESS3-4). RST.11-12.8 Evaluate the hypotheses, data, analysis, and conclusions in a science or technical text, verifying the data when possible and corroborating or challenging conclusions with other sources of information. (HS-ESS3-2), (HS-ESS3-4) Mathematics. MP.4 Model with mathematics. (HS-ESS3-3), (HS-ESS3-6) HSN.Q.A.1 Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays. (HSESS3-1), (HS-ESS3-4), (HS-ESS3-6) 28 The Science Teacher Finding the CO2 Culprit On the web CO2 emissions summarized by country: http://bit.ly/1plWkqG Global Fossil-Fuel CO2 Emissions from Oak Ridge National Laboratory: http://1.usa.gov/1u6FjiR How do we know anything for certain? blog: http://bit.ly/1xEcvV5 References Anthropogenic influences have far more impact than the planet’s natural volcanic processes. issue (Clary and Wandersee 2012a, 2014). We also documented how less inclusion of climate change topics resulted in persistent non-scientific opinions (Clary and Wandersee 2012b). We propose that even examining peer-reviewed research on the topic won’t have as great an impact on learning as retrieving climate data, graphing and analysis of volcanic and human CO2 contributions, and reflection upon the results. In the CO2 Culprit activity, students directly visualize results of data collection, computer modeling, and the influences of humans and Earth processes on global atmospheric CO2. Graphs reveal that sustained, anthropogenic influences have far more impact than the planet’s natural volcanic processes. Graphs also reveal that humans contributed to the rising amounts of CO2, but volcanic processes exhibit stability. Even when larger volcanic eruptions are considered, the total CO2 output by volcanoes is stable when compared to the scale of human CO2 emissions. We invite our colleagues to try the CO2 Culprit activity and engage students with authentic climate data and graphical representation in the classroom. ■ Renee Clary ([email protected]) is an associate professor of geosciences and director of the Dunn-Seiler Museum at Mississippi State University. She also directs the EarthScholars Research Group, www.EarthScholars.com, and the 15 Degree Laboratory, www.15degreelab.com. The late James Wandersee was an emeritus professor of biological education at Louisiana State University and founder of the 15 Degree Laboratory. Boden, T.A., G. Marland, and R.J. Andres. 2013. Global, regional, and national fossil-fuel CO2 emissions. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, TN. http://1.usa. gov/13rCcKO Clary, R.M., and J.H. Wandersee. 2012a. Mandatory climate change discussions in online classrooms. Journal of College Science Teaching 41 (5): 70–79. Clary, R.M., and J.H. Wandersee. 2012b. Optimizing online discussion board forums’ content and time parameters for increased student scientific literacy. Society for College Science Teachers Programs and Abstract 32: 15. Clary, R.M., and J.H. Wandersee. 2014. Optimization of discussion forums for online students’ climate literacy. Journal of Geoscience Education 62 (3): 402–409. Cook, J., D. Nuccitelli, S.A. Green, M. Richardson, B. Winkler, R. Painting, R. Way, P. Jacobs, and A. Skuce. 2013. Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters 8: 024024. http://bit.ly/1cIm6KL Gerlach, T. 2011. Volcanic versus anthropogenic carbon dioxide. EOS 92 (24): 201–203. http://bit.ly/1Iwd59x Intergovernmental Panel on Climate Change (IPCC). 2013. Climate change 2013: The physical science basis. http://bit. ly/1zOAsY0 Leiserowitz, A.A., E.W. Maibach, C. Roser-Renouf, N. Smith, and E. Dawson. 2013. Climategate, public opinion, and the loss of trust. American Behavioral Scientist 57 (6): 818–837. National Governors Association Center for Best Practices and Council of Chief State School Officers (NGAC and CCSSO). 2010. Common core state standards. Washington, DC: NGAC and CCSSO. NGSS Lead States. 2013. Next Generation Science Standards: For states, by states. Washington, DC: National Academies Press. Oreskes, N. 2004. The scientific consensus on climate change. Science 306 (4702): 1686. http://bit.ly/1GR1QFZ Oxburgh, R. 2010. Report of the international panel set up by the University of East Anglia to examine the research of the climatic research unit. http://bit.ly/16JRpcx Russell, M., G. Boulton, P. Clarke, D. Eyton, and J. Norton. 2010. The independent climate change e-mails review. http://bit. ly/1v9kvGy Singh, V. 2013. How do we know anything for certain? Climate Change: Learning, communicating, acting. http://bit.ly/1x3Vpgy Summerhayes, C. 2011. Dragon’s den CO2—volcanic or anthropogenic? Geoscientist 21 (8): 18–21. March 2015 29