“We have started to clean up your mess. And we will not stop until we are done.” – Greta Thunberg

In 2018, teenager Greta Thunberg held her first school strike; she skipped school to camp outside the Swedish parliament, asking politicians to take immediate climate action. What began as an individual student's demand for change has now grown into global climate strikes in which activists and youth around the world gather outside their local parliaments to demand that the government address the climate crisis. But what psychological factors could help explain Thunberg’s contribution to global climate activism?  How broad is her impact? Is she simply preaching to the choir or is she reaching diverse audiences?

Based on a nationally representative survey of over 1,300 U.S. adults, we found that Americans who report greater familiarity with Greta Thunberg also feel more confident that by working together with others, they can mitigate climate change. They are also more willing to take collective actions such as signing petitions, pressuring elected officials, and making donations to address climate change. We call this the “Greta Thunberg Effect.”

By the Greta Thunberg Effect we of course do not mean to imply that a single exposure to Greta Thunberg causes people to turn into climate activists. Instead, we documented a potentially important pattern of relations that may explain why Thunberg has been able to mobilize collective action: people who report being familiar with her feel more empowered to make a difference, which in turn correlates with their willingness to act on climate change. 

Why the Greta Thunberg Effect?

Typically, well-established figures (such as Pope Francis or James Hansen) have mobilized climate action presumably in part due to their religious and academic authority. But Greta Thunberg lacks any authority or elite status. How then has she been able to empower more than 10 million people worldwide?

To feel empowered, people need to believe that change is possible. Thunberg proclaims that “there is still time to change everything around.” Moreover, her Fridays for Future campaign mobilizes students to take part in climate strikes every Friday for the sake of their shared future on this planet. The campaign exemplifies that anyone—even young students—can make a difference through civil action. Most importantly, Thunberg’s actions live up to her words—she challenges powerful leaders and institutions at various international platforms, such as the United Nations.

Therefore, Greta Thunberg embodies what psychologists refer to as “collective efficacy,” or demonstrating that by working with others, anyone—even someone without elite status or authority—can contribute to change.

We also wanted to understand how prevalent the Greta Thunberg Effect was among various audiences. Thunberg is often considered a youth icon, and her demands align with liberal policy preferences. Could young and left-leaning Americans relate more to her than older or more conservative Americans, and therefore be more strongly influenced by her?

Surprisingly, we found that the Greta Thunberg Effect is similar across age groups, although we did not survey children and teens, who we suspect might be most strongly influenced by Thunberg because she began her activism as a school student. We also found that the Greta Thunberg Effect was present across the political spectrum, although it was stronger among liberals than conservatives.

Correlation Does Not Equal Causation

How can we be sure that our findings reflect Greta Thunberg’s unique influence, and are not just the result of people’s general support for the environment? Although we cannot be entirely sure, we found that the effect of people’s familiarity with Greta Thunberg remained relevant even after taking into account their general support for climate activism and their political ideology. Political ideology is strongly related to people’s concern about climate change. Therefore, being familiar with Thunberg appears to have a unique influence on people’s willingness to take action, even after accounting for these other motivations.

But what if the direction of influence went the other way? Is it possible that people already motivated to take climate action are more likely to be familiar with Greta Thunberg? Although this is possible, our analysis did not support this “reverse-effect” well.  Of course, reality may be even more complex and dynamic; being engaged in climate activism might well lead to more exposure to Greta Thunberg, which in turn might lead to even more activism.

What Does This Tell Us About Climate Action?

The patterns in our data suggest that people may feel motivated to take action when they are exposed to inspirational leaders such as Greta Thunberg who provide hope and evidence that change is possible. How can activists further amplify their impact? Considering political differences on climate change, they must appeal to people across the political spectrum. The Greta Thunberg Effect tells us that calls to action need not remain within echo chambers—they can reverberate globally, empowering millions to work together to make a difference.

For Further Reading

Sabherwal, A., Ballew, M. T., van der Linden, S., Gustafson, A., Goldberg, M. H., Maibach,     E. W., Kotcher, J. E., Swim, J. K., Rosenthal, S. A., & Leiserowitz, A. (2021). The Greta Thunberg Effect: Familiarity with Greta Thunberg predicts intentions to engage in climate activism in the United States. Journal of Applied Social Psychology. doi: 10.1111/jasp.12737. https://onlinelibrary.wiley.com/doi/10.1111/jasp.12737

Roser-Renouf, C., Maibach, E. W., Leiserowitz, A., & Zhao, X. (2014). The genesis of climate change activism: From key beliefs to political action. Climatic Change125(2), 163-178. https://doi.org/10.1007/s10584-014-1173-5

Swim, J. K., Geiger, N., & Lengieza, M. L. (2019). Climate change marches as motivators for bystander collective action. Frontiers in Communication4, 4. https://doi.org/10.3389/fcomm.2019.00004


Anandita Sabherwal is a doctoral student in the Department of Psychological and Behavioural Science and the Grantham Research Institute for Climate Change and the Environment at the London School of Economics and Political Science.

Sander van der Linden is Professor of Social Psychology in Society and Director of the Cambridge Social Decision-Making Lab at the University of Cambridge. He is also a research affiliate with the Yale Program on Climate Change Communication.

Janet K. Swim is a Professor of Social Psychology at the Pennsylvania State University and chair of the Pennsylvania State University College of Liberal Arts Sustainability Council.