Download Investigating whether man or mountain emits more atmospheric

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