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The Gaia Hypothesis: How to Teach Climate Change Without Heated Debates

This professor’s systems approach—using computer models and a made-up world—can be adapted to suit any complex or controversial subject.


Max Berkelhammer, PhD

Assistant Professor, Earth and Environmental Sciences, University of Illinois, Chicago

PhD in Earth Sciences, Postdoctoral Research Associate in Atmospheric and Oceanic Sciences, BA in Geology

Almost anywhere you go, the subject of climate change is likely to stir up a firestorm of controversy. Anywhere, that is, except the classroom of Dr. Max Berkelhammer, a professor of earth sciences at the University of Illinois, Chicago.

To prevent politics and emotion from clouding the issues he covers in his Earth Systems course, Berkelhammer focuses on instilling in students a deep understanding of statistical analysis so that they can make an informed, objective decision about what is happening to the planet’s climate.

He begins by taking Earth out of the equation entirely. Instead, he has students create a computer-generated ecosystem on a planet called DaisyWorld, then run a series of simulations to see what happens when they disrupt temperature, weather patterns, and species populations. It quickly becomes apparent how even seemingly small changes can perturb an entire system.

“My first year teaching, I worked on an independent project with a student whose parents worked in the oil industry,” Berkelhammer recalls. “She started out as a climate skeptic, but after a yearlong project examining tree rings, she did a 180. I never injected my own opinion very strongly; I just gave her the tools to look at the data—and the luxury to draw her own conclusions in time.”

In the lesson described below, Berkelhammer shares the specifics of his approach, which is based on the Gaia hypothesis, and explains why it has such a profound effect.


A topic tainted by emotion and politics

Many students come to class with preconceived notions about climate change that can cloud their ability to view it scientifically. Further, the Earth’s ecosystems are hugely complex. Even through an objective lens, it can be difficult to comprehend how and why events affect one another.


Fostering objectivity with computer simulations

To ensure that beginning earth science majors are set up to think about the topic rationally, Berkelhammer has them create and choreograph a simpler ecosystem using computer modeling, then test their projects under various circumstances so that they can witness firsthand the delicate dance of the environment.


“My goal is for students to recognize how different components of the planet are intertwined and that when one cycle changes, that change propagates, affecting all other systems.”

— Max Berkelhammer, PhD

Course: EAES 285 Earth Systems

Course description: Students attend the lecture and computer lab twice a week. Approximately midway through the semester the class transitions to a project-based mode that focuses on creating a climate simulation to examine a question about how components of the Earth System may be affected by rising greenhouse gasses. The emphasis is on geoscientific thinking, problem solving, and data analysis.

See materials shared by Max Berkelhammer, PhD

See materials

Lesson: DaisyWorld and beyond–An introduction to ecosystems

In Berkelhammer’s Earth Systems course, the crux of the class is an original project he assigns about halfway through the semester.

“I always start this class with a famous example in climate science called DaisyWorld, to explore the interaction between life and its environment,” says Berkelhammer. The approach is based on the Gaia hypothesis—after the Greek “Mother Earth” goddess—which asks students to consider a single, self-regulating system to explore how living organisms both alter and are altered by their surrounding environment.

In DaisyWorld, that system involves a very simple planet on which the only living thing is white daisies. Here, rising temperatures stimulate the daisy population to grow. As their white petals reflect more and more light, the surface temperature of the planet begins to drop. Eventually, it becomes too cold to sustain life for the flowers. As they begin to die off, fewer petals mean less reflection of light, so temperatures climb upward again. When it is warm enough, the daisies begin to repopulate, and the cycle repeats.

“One of the things I like about this example is the aha! moment you see from students,” says Berkelhammer. “They grasp that what drives the behavior of this very simple planet is the presence of biology—the fact that living organisms modify their environment, and how relationships between the components emerge.”

Berkelhammer believes that almost any topic can be explained through the sum of its interrelated parts. He offers the following suggestions for other educators who wish to employ a systems-based approach in their teaching.

Begin with a simple, relatable example

DaisyWorld is such a persuasive teaching tool because its imagery relies on a familiar flower and some very basic scientific facts about the effects of heat and light. Berkelhammer says that using simple examples that incorporate well-known objects and an easily observable phenomenon will make the material more accessible. Once the ideas click, it will be easier for students to then study more complex systems.

Challenge students’ assumptions

“It is important to fully understand what an ecosystem encompasses,” Berkelhammer says. Many of his students come to class with the perception that environmental terms, such as “ecosystem,” apply to forests, lakes, mountains, and the like. They do not realize that they refer to urban areas as well. For instance, cities undergo a phenomenon known as “the heat island effect” when vegetation is paved over by asphalt and concrete for roads, buildings, and other structures. Because these materials absorb rather than reflect the sun’s heat, surface temperatures rise.

“By explaining this theory in detail, the concepts of human influence on the climate becomes obvious. Then, more complex problems, such as global warming and greenhouse gas effects, become more tangible and relatable,” he says. “And, since that helps explain the science of why cities are hotter, it’s not a difficult extension to see why the entire planet may be warming.”

Stick to the facts

Let evidence tell the story, Berkelhammer advises. If your subject inspires an emotional reaction, help your students step back and focus on well-established, black-and-white, irrefutable information and facts. Trust that stripping away preconceived notions will allow them the time and space they need to reach rational conclusions on their own.

Let the students lead

Berkelhammer says he lets students guide the pace and, to some extent, the direction of the class. “Such comments as, ‘We really don’t have time to go into that …’ can degrade the ability to work through difficult problems,” he explains.

Begin with brains, not computers

Einstein, Galileo, and Newton made some of the greatest discoveries in human history without the aid of a supercomputer or the benefit of Google. While Berkelhammer does require the use of a laptop in his class (technology, he says, virtually all students own), he emphasizes the importance of imagination or what he calls “thought experiments.” Using only the mind’s eye to draw conclusions can be a compelling approach to problem solving, he notes.

“A few years ago, after a major snowstorm I asked the students to figure out how much snow was in the city and how much energy it would take to melt all this snow,” he says by way of example. “I had no idea what the answer to this problem [was], and the answer could not be found online. There is a kind of luxury to these problems, because there is not a pressure to get the right answer—only to use strong reasoning.”

Start simple, then build

After he establishes a premise using a simple model, Berkelhammer likes to keep expanding upon it to ask ever more complicated and interesting questions. What if you were to introduce black daisies into DaisyWorld? Or a different species entirely? How about altering air composition, soil components, or rain levels? Asking students to consider different angles and elements will stretch them to think more deeply about interconnectedness within a system.

Foster ingenuity

Berkelhammer suggests assigning projects that push students to dream up unique ways to apply the concepts you teach. For example, although it is a requirement of Earth Systems to run a computerized climate simulation, Berkelhammer extends a lot of latitude in the execution of the assignment. “They’ve looked at everything from how the extinction of African elephants could set off a chain reaction within a larger ecosystem to how volcanos might be used to offset global warming,” he says.

“I don’t formally talk about how to counter climate denialism … [or] how to engage with someone who comes at you with opposing ideas. But I do train them in how to talk about the science to all levels—from elementary schoolers to their parents and the public.”

— Max Berkelhammer, PhD
Prepare them to share what they know

Berkelhammer believes that his job is to teach science and leave climate activism to those outside the classroom. “I don’t formally talk about how to counter climate denialism, though I do create a lot of opportunities for students to get out and talk to the public,” he says. That said, he feels students should be prepared to speak with confidence on their chosen discipline, and he has arranged for them to give presentations at local high schools and other venues. “I don’t necessarily coach them on how to engage with someone who comes at you with opposing ideas, but I do train them on how to talk about the science to all levels—from elementary schoolers to their parents and the public.”

Teach to the students’ interests, not the syllabus

Besides his duties as an assistant professor, Berkelhammer is still an active researcher who studies the way that the land surface impacts the atmosphere. Teaching Earth Systems for the past two years has allowed him to share his studies—and his passion for the environment—with the next generation. He feels he has done his job well when he has not worked through all of the material that was planned for the semester.

“I think I make more of an impact when I’m peppered with questions that lead to a discussion about students’ specific interests,” he says. At times, as seen below, this personal attention has helped change the trajectory of a student’s career.


Berkelhammer says modeling an environment is an invaluable lesson because students can see with their own eyes how even very simple systems can be thrown into turmoil by the slightest alteration. As the simulations play out before their eyes, it is not such a leap to envision how an ecosystem as large and complex as the Earth’s might respond when subjected to human activity and any number of other stressors.

There is compelling evidence that Berkelhammer’s approach resonates: He is already the recipient of several teaching awards, including the Excellence in Teaching Fellowship, a new program developed by Course Hero and the Woodrow Wilson National Fellowship Foundation to support the nation’s early-career faculty members.

Berkelhammer has had more than a few students express enthusiasm for the earth sciences, choosing to continue in the field after taking his class. One woman, who was relatively quiet and unassuming during the semester, surprised him by asking for an independent project. She ultimately went on to work in his research lab and now serves as a research scientist on a prestigious study.

“I wouldn’t take credit for her success,” Berkelhammer says. However, given what we know about systems, it is more than likely that the introduction of a passionate and caring professor into a classroom “system” might have something to do with students blossoming and thriving.

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