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MIT Better World

By Kara Baskin

The hard part is getting them to fight it. Why? Even as temperatures climb and natural disasters rage, the phenomenon seems overwhelmingly complex, distant, and abstract, says John D. Sterman PhD ’84, the Jay W. Forrester Professor of Management and faculty co-director of the MIT Sloan School of Management Sustainability Initiative.

“A lot of people still hold a mental model that says, ‘Let’s wait and see how badly climate change is going to hurt us before acting,’” he notes. “Folks think it’s like putting the kettle on the stove to boil water. They think you can wait until you hear the whistle to take the kettle off the flame.” But climate change isn’t like your tea kettle. Every effort to “turn down the heat” takes time, from implementing climate-friendly policies to seeing declines in greenhouse gas (GHG) emissions.

We can’t wait for the kettle to boil over, Sterman says. By the time the damage is clear enough to motivate strong action, it will be too late. That’s why Sterman and colleagues have developed interactive climate policy simulation models grounded in peer-reviewed science; each lets people experience firsthand how various decisions affect the fate of humanity.

Created by the MIT Sloan Sustainability Initiative together with the nonprofit think tank Climate Interactive, the simulations are frequently used in role-playing games and workshops for policy makers, leaders in business and civil society, educators, and laypeople. C-ROADS (Climate Rapid Overview and Decision Support), launched in 2009, focuses on how changing national and regional emissions affects climate outcomes. En-ROADS (Energy Rapid Overview and Decision Support), released in 2019, explores what actions and policies can cut emissions quickly and deeply enough to limit global warming and climate change.

People can use both models, which are freely available online, to experiment with different policies and see immediate results. Through the MIT Climate Pathways Project, Sterman along with fellow MIT alumni Michael Sonnenfeldt SB ’77, SM ’78, the Sustainability Initiative’s Bethany Patten EMBA ’13; Drew Jones SM ’97; and Ben Wolkon MBA ’16 have facilitated interactive En-ROADS briefings with senior policy makers and negotiators around the world, including dozens of US senators, members of the House of Representatives, governors and other elected officials. To date, more than 100,000 people in over 90 countries have used the simulations.

The power of simulation

The success of both simulators is rooted in psychology, Sterman says. “People learn best from experiment and experience,” but experiments are often impossible, he notes. “Today, whether it’s learning to fly an aircraft, perform surgery, or tackle climate change, experience comes too late. In such settings, people learn best in simulations.”

Simulations are especially important because evidence alone rarely changes human behavior, Sterman adds. Explaining research-based facts and then assuming policy will change—what Sterman describes as the “deficit model” of science communication—is futile, he warns. The “deficit model” says the public suffers from a deficit of understanding that only experts can fill.

But while science and evidence are essential, Sterman notes, with a hint of irony, “Research shows that showing people research doesn’t work.” The Covid-19 crisis provides a clear example: scientists caution against large gatherings and urge mask wearing, but adherence has tragically fallen short.

In contrast, hands-on simulations allow people to come to their own conclusions by experimenting with scenarios they choose and receiving instant feedback about the likely consequences.

Both simulations are easy to use. In En-ROADS, for example, users swipe sliders to try different policies, such as pricing carbon pollution, slashing deforestation, or promoting energy-efficient buildings and transportation. Players build scenarios and immediately see the likely effects on energy demand, production, and prices; GHG emissions; global warming; sea level rise; and other factors. Users can also change a wide variety of assumptions, from future population growth to the timeline for retiring coal plants, and see what happens.

President Joe Biden has identified climate change as a priority in his administration, and more nations and businesses have pledged to become carbon-neutral by mid-century. “These changes are great news,” Sterman says, but he emphasizes that “pledges aren’t policies.” Real change, he stresses, requires broad bipartisan support for legislation, regulations, and incentives strong enough to boost energy efficiency, deploy renewables faster, and build a vibrant economy while cutting GHG emissions and keeping the remaining fossil carbon in the ground.

En-ROADS is designed to help people discover which actions work well and which do not, and it reveals how policies interact (try En-ROADS yourself at

Complex dynamic systems often generate counterintuitive behavior, explains Sterman, who is director of the MIT Systems Dynamics Group and a leading authority on system dynamics, a methodology that examines complex systems and their myriad interactions. He is also the author of Business Dynamics, the key textbook in the field. Intuitively appealing actions often fail or even worsen the problems they were intended to solve, because the best points of leverage are far removed from where the pain emerges, he says. (For example, traffic congestion often leads to building more roads, but new roads increase the attractiveness of driving, soon worsening congestion.) System dynamics provides a way of looking at such issues not by providing answers, but by helping people change their mental models, as Sterman puts it.

Interactive simulators like En-ROADS work, Sterman says, because they give users autonomy to design and test their own climate solutions. People can subsidize nuclear power or promote renewables, put a price on carbon pollution or ban coal power.

Sterman and colleagues use C-ROADS and En-ROADS for facilitated group-learning experiences such as the Climate Action Simulation. In this game, participants play the roles of delegates to an emergency UN climate summit, and they negotiate policies to limit warming to the goals set out in the 2016 Paris Agreement. Each “stakeholder” has a different agenda, and together they represent a range of interests, from clean tech to the fossil-fuel industry, from Indigenous peoples to superpowers.

Evaluations based on a sample of more than 2,000 participants from diverse nations, ages, and backgrounds found the experience not only boosted participants’ knowledge about climate change and what can be done to limit it, but more importantly, generated strong emotional responses, Sterman says.

According to Sterman, those emotions are critical. “Motivating people to act isn’t just about information. The evaluative studies showed it’s that emotional engagement that drives people’s desire to learn more and to take action.”

Notably, the experience is effective with people across the political spectrum: “liberals and conservatives, environmentalists and business people. That’s important,” he says, “because everyone is needed.”

“We are rigorously nonpartisan,” Sterman explains. “Participants try the policies they want to explore, learning for themselves about the economic, health, and national security threats of climate change—and, even more importantly, what we can do to build a safe, healthy, and prosperous world.”

Beyond denial and despair

That’s the real benefit to the simulators: they offer a way forward. “Climate communication is too often passive, complex, and overwhelming, leading many to denial or despair,” he says. Building sustainable scenarios in C-ROADS and En-ROADS fosters what Sterman calls “grounded hope,” hope rooted in science.

“Hope isn’t naïve optimism—the belief that some technological breakthrough will save us, without the need for us to change,” Sterman concludes. “Hope is the belief that what we do matters, that, although there’s no time to waste, it’s not too late. It’s the belief that working together, we can create a better world.”

*Sources include the Yale Program on Climate Change Communication