How we know what we know: Advancing climate change education

Nicole Holthuis, Andrew Wild, Rachel Lotan,

Jennifer Saltzman, and Mike Mastrandrea

Abstract

Climate change is one of the most complex scientific and social challenges we face today.

Learning about climate change offers rich opportunities for students to learn both what we know about the causes and effects of climate change and how we know what we know. In this article, we describe what we learned from working with middle and high-school science teachers as they taught a unit about climate change in their classrooms. We provide examples of curricular activities that facilitate students’ understanding of the tools used to collect climate change data, support their construction of arguments, and help them grasp characteristics of scientific theories. By doing so, climate change education provides an excellent opportunity for students to connect science content, scientific practices, and the nature of scientific knowledge, as advocated for by the Next Generation Science

Standards.

Introduction

Climate change is one of the most complex scientific and social challenges we face today. It is also one of the most complex topics to teach. It is politically-laden and perceived as controversial, at least in part, because of the coverage of climate change "deniers" and the media attention. But unlike some other controversial topics in science, it also has

immediate implications for contemporary human behaviors and societal practices.

As the field has developed, educators and scientists have come to understand that a deficit

model of knowledge doesn’t explain why people continue to disagree about climate change.

Our team of science educators, teachers, and climate scientists at the XXXXX Climate

Change Education Project developed curriculum materials that advance students' ability to

separate scientific evidence from beliefs and values, making them critical consumers of

information. This curriculum provides students with opportunities to grapple with what

we know about climate change and how we know it. In doing so, scientific content and

practices identified by the Next Generation Science Standards (NGSS Lead States, 2013)

become inextricably linked (Figure 1).

Disciplinary Core Ideas • ESS2.D: Changes in the atmosphere due to human activity have increased carbon dioxide concentrations and thus affect climate. (HS-ESS2-6),(HS-ESS2-4) • ESS3.D: Though the magnitudes of human impacts are greater than they have ever been, so too are human abilities to model, predict, and manage current and future impacts. (HS-ESS3-5)

Science and Engineering Practices • 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 assumptions that theories and laws that describe the nature world operate today as they did in the past and will continue to do in the future. (HS-ESS3-1) • Construct an oral and written argument or counter arguments based on data and evidence (HS- ESS2-7)

Connections to Nature of Science • Scientific investigations use diverse methods and do not always use the same set of procedures to obtain data. • New technologies advance scientific knowledge. • Scientific knowledge is based on empirical evidence. • Scientific arguments are strengthened by multiple lines of evidence supporting a single explanation.

Figure 1: Connections to the core ideas, scientific practices, and nature of science as described in the Next Generation Science Standards

2 What does this look and sound like in the classroom? In this article, we describe what we learned from working with thirty-seven middle and high-school science teachers across the

San Francisco Bay Area, as they taught the XXXX Climate Change Curriculum

(climatechange.XXXX.edu) in their classrooms. We focus on three questions that teachers explored with their students: 1) Where does climate change data come from and how is it collected? 2) What conclusions can, and cannot, be made from these data? and 3) How has our understanding of climate change developed over time from making claims to building theories? By examining these important questions, climate change education provides an excellent opportunity for students to connect science content, scientific practices, and the nature of scientific knowledge, as advocated for by the Next Generation Science Standards.

Where does evidence come from?

Scientists tell us that the average global temperature and atmospheric CO2 levels are at their highest level in over 450,000 years (Figure 2). But, thermometers were not invented until 1724.

Figure 2: CO2 level and Temperature 450,000 years ago to present. Reprinted from Let’s face the truth about climate change mitigation (I) by julienx2k2, 2007, Retrieved November 30, 2013, from blaskarm.wordpress.com/2007/09/14/lets-face-the-truth-about-climate-change-mitigation-i/. Original data: Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M., Chappellaz J., Davis J., Delaygue G., Delmotte M., Kotlyakov V.M., Legrand M., Lipenkov V., Lorius C., Pépin L., Ritz C., Saltzman E., Stievenard M., 1999, Climate and Atmospheric History of the Past 420,000 years from the Vostok Ice Core, Antarctica, Nature, 399, pp.429-436. 3

So how do we know? Where does the evidence come from?

One powerful source of data comes from ice cores. Drilling into ice sheets in

Greenland and Antarctica allows us to Figure 3: Scientist and ice core. Reprinted from Ice Core Drills, measure the atmospheric conditions of 2010, Retrieved October 2, 2013, from http://www.icedrill.ch/. Copyright 2007 by Dieter Stampfli. Reprinted with permission. the past. Each winter new snow falls on top of previously un-melted snow. This process

creates distinct layers of ice each year; summer ice

appears light while winter ice appears dark. By

drilling thousands of feet deep, researchers extract

cores of ice formed hundreds of thousands of years

ago. Air bubbles are trapped in the ice as it is

formed. Analysis of the trapped gases and the

chemical composition of the ice itself helps scientist

know what the climate was like thousands of years Figure 4: Ice core from a depth of 1855 m. Reprinted from Paleo Slide Set: Polar Ice Cores by A. ago. The most famous site where data are found is Gow, 2001, Retrieved November 30, 2013 from http://www.ncdc.noaa.gov/paleo/slides/slideset/ 15/15_281_slide.html. Public image. in Vostok, a Russian station near the South Pole.

We observed classrooms as students learned about ice cores. One teacher had students create their own “ice core strips. Students counted and labeled the number of seasons

4 represented. Then each band was assigned a temperature based on a simulated gas analysis of that band. Students graphed the temperature data over time. As students discussed the Vostok ice core data, they came to realize that while the Earth has experienced natural heating and cooling cycles in concert with variations in greenhouse gas levels in the atmosphere, more current measurements show a fundamentally different pattern.

Scientists have compared ice core and other proxy data with direct measurements of CO2 from the past several decades. Comparing these data indicates that the current CO2 levels are higher now than they have been for at least 800,000 years, with a sharp rise in CO2 since the Industrial Revolution (mid-1700s). Detailed estimates of CO2 sources and sinks provide clear evidence that CO2 levels are increasing as a result of human activities.

From evidence to claims

As noted in the NGSS (2013), data and evidence are the foundation for developing claims.

The wealth of climate change data—both raw and processed—provides unique opportunities for students to synthesize and analyze data in order to make sense of it and to come to some conclusions. Thus, the curriculum materials were designed around six objectives, one of which states: “Students will use data and evidence to justify claims relating to climate, climate change, and mitigation.”

5 • How do we know that? Teachers often began the unit by asking students to • Scientists didn’t always know _____. • How certain are we/scientists about that? consider how we know what we know. Teachers • What makes you think that? • What’s your evidence? • How would you know if you were wrong? framed this question of “how we know” in many ways • How did you arrive at that conclusion?

(see Figure 5). Figure 5: Questions to Promote “How do we know” Talk in the classroom Ms. X presented the Mauna Loa graph

(Figure 6) to her students. “What do you

make of this graph?” she asked. Students

discussed in pairs what the data suggested

and what they could conclude from it.

Figure 6: Graph discussed in Teacher H1 Class. Atmospheric Carbon Dioxide. Reprinted from Wikipedia “Carbon dioxide emissions are going up,” Commons - "Atmospheric Carbon Dioxide” by R. A. Rohde, 2008, Retrieved November 30, 2013 from http://commons. responded one student. wikimedia.org/wiki/File:Mauna_Loa_Carbon_Dioxide-en.svg. Public image.

In another class, after a student stated incorrectly that greenhouse gases were the most

abundant gases in the atmosphere, the teacher took the opportunity to pose another

question: “How do you know that greenhouse gases are the most abundant?” By

structuring the questions in this way, she was no longer the ultimate authority, the evidence

was. As the student began to talk through the data on the board, he came to realize that the

data contradicted his claim. This provided him the opportunity to improve in his ability to

support a claim with evidence. The teacher also set an expectation: if you make a scientific

claim, you must have evidence to support it.

6 Students worked in small groups to practice making claims and supporting them with evidence. For example, in one science class, four students were examining a graph (Figure

7) that showed the predicted “magnitude of

adverse impact” on various natural

ecosystems given an increase in

temperature between 0 and 4 degrees

Celsius. One group member made a claim Figure 7: Impact of Climate Change on Natural Ecosystems that the magnitude of impact goes up over time (recently versus later). Another student pointed out that “it doesn’t really say timeline.

It says ‘Celsius’.” They then revised their claim: “A temperature change of 4° Celsius would badly change the environment.”

To support students as they gain and enhance their ability to formulate solid scientific claims, teachers can model, make explicit references to, and label the distinct features of a scientific argument. In one class, students discussed the evidence for climate change presented in a somewhat complex graph. After a discussion of the graph, the teacher summarized: “So that is a good statement of evidence, right? I’ve said what my graph shows, I’ve talked about what the trend is….I’ve told you what years I was looking at. So, when [you] present evidence, that’s the kind of statement that I’m looking for. I want a very concrete statement that has all of those pieces, if possible.” This type of meta-talk provides students opportunities to realize how scientific understanding may differ from the everyday conclusions or colloquial ways of talking about data and claims. It promotes specialized science discourse in the classroom.

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From claims to theories

Science textbooks often portray a world of firm conclusions, with the underlying evidence occasionally acknowledged (Bowen & Roger 2008; Roth, Bowen & McGinn 1999). As a result, Hodson (1998) argues, students may begin to think that theories are formulated from a few bits of evidence and, conversely, are abandoned because of a few negative results. In reality, “theories are only abandoned when there is compelling evidence (long- standing and striking at the fundamental core of the theory)….In practice, all theories have to live with anomalous data; it is a natural feature of science.” (p. 194) Moreover, argumentation, not dismissal of the previously established theory, is the process by which scientists evaluate and critique the evidence and its coordination with theory. When it comes to climate change, misunderstandings about the nature of scientific knowledge lead to some of the faulty arguments used to deny the existence of anthropogenic climate change.

In one class, the teacher examined with her students how our understanding of climate systems and climate change has developed and changed over time. In ancient times, people began to suspect that a region’s climate could change over a long period. In the 18th and

19th centuries, people began to observe, in a single life-time, how human activity can alter the environment, though few believed humans could actually alter the climate of the planet as a whole.

8 Then in, 1827, Joseph Fourier published work in which he postulated that the Earth’s atmosphere kept the planet warmer than it would be if the planet existed in a vacuum. He also suspected that changes in human activity and natural forces could actually change the

Earth’s climate over long periods of time. In 1896, Swedish scientist Svante Arrhenius published calculations predicting that the planet’s average temperature would increase as humanity burned fossil fuels such as coal. Many rejected his claim thinking that humanity could never affect the vast climate cycles. This was the beginning of a more than 100-year history of ever-more careful measurements and calculations to pin down exactly how greenhouse gas emissions and other factors influence Earth’s climate (Weart 2008). By the

1950s, a growing number of scientists were concerned that carbon dioxide emissions would lead to an increase in the Earth’s temperature. In 1960, Charles Keeling documented that the level of CO2 in the atmosphere was in fact rising. Concern mounted year by year along with the rise of the “Keeling Curve” of atmospheric CO2 (Keeling and Whorf 2004).

Scientists’ understanding of climate change has increased, as has their certainty about what is happening. Yet, scientific certainty and uncertainty is a widely misunderstood concept.

We observed teachers and students as they examined how and why our certainty about climate change has changed over time. In a tenth grade classroom, students were working in a group, examining global land-ocean temperature records (see Figure 8). One group member stopped the teacher to ask:

S1: Ms. J, what’s the green line?

9 T: The green is something that you

may or may not have heard of

before… It’s just looking at our

level of uncertainty or possible

errors within our data. So, as

time progresses, what happens

to that green bar? Does it get

longer or shorter? Figure 8: Graph discussed in the Ms. Js class. Global Land-Ocean S1: Smaller. Temperature Index. Reprinted from GISS Surface-Temperature Analysis, 2013, by National Aeronautics and Space Administration, Retrieved November 30, 2013 from http://data.giss.nasa.gov/gistemp/graphs_v3/. T: It gets shorter. So, what would Public image.

that tell us? Could there be more room for error?

S1: Less error.

T: Less room for error. Right?

S2: Because we have more data? Technology is better?

T: Both reasons, yeah. So, back here, you know, we had some good… we had some means

of measurement but it wasn’t the best technology.

This example illustrates ways in which teachers and students might discuss uncertainty-- considering the precision of measurements over time and the distribution of those measurements around the world, for example. 1

1 For more information, see Hanson, J., Ruedy, R., Sato, M. and Lo, K. (2010) Global Surface Temperature Change. Review of Geophysics. 48.

10 Conclusion

Learning about climate change offers rich opportunities for students to learn both what we know about the causes and effects of climate change and how we know what we know. Since fallacious or misleading arguments about climate charge are often rooted in misconceptions about the nature of science, it is important for students to learn how scientific knowledge about climate change has developed. By engaging in the practice of argumentation, students are likely to develop a stronger conceptual understanding of the content, better grasp about how scientific knowledge is constructed, and the development of scientific theories over time.

It can be challenging and time-consuming to facilitate students’ understanding of the tools used to collect climate change data, support the construction of arguments, and help them grasp characteristics of scientific theories. We have provided some examples of what this teaching and learning looks like in practice and we have offered some information about the nature of the data and scientific theories. By teaching what we know about climate change science and how we know it, students have a greater capacity to make scientifically informed decisions and to interpret climate change information from a more critical perspective.

References

Bowen, G., W-M. Roth, and M. McGinn. 1999. Interpretations of graphs by university biology students and practicing scientists: Toward a social practice view of scientific representation practices. Journal of Research in Science Teaching 36(9); 1,020-1,043.

11 Bowen, G. M. and V. Rodger. 2008. Debating global warming in media discussion forums: Strategies enacted by “persistent deniers” and implications for schooling. Canadian Journal of Enviornmental Education 13(1); 89-106.

Hodson, D. (1998). Science fiction: The continuing misrepresentation of science in the school curriculum. Curriculum Studies 6(2); 191-216.

Keeling, C. and Whorf, T. (2004). Atmospheric CO2 from continuous air samples at Mauna Loa Observatory, Hawaii, U.S.A. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory.

NGSS Lead States. 2013. Next generation Science Standards: For states, by states. Washington, DC: The National Academies Press.

Weart, S. 2008. The Discover of Global Warming. Boston, MA: Harvard University Press.

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