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The Psychology of Hothouse Earth

Preventing climate disasters requires changing concepts, beliefs, and values.

The scariest article I've read this year argues that scientists may have been underestimating the effects of global warming on human life (Steffen et al. 2018). An international group of scientists argues that interactions among factors such as glacier erosion, permafrost melting, and ocean currents may turn our planet into Hothouse Earth. By the end of the century, temperature increases greater than the 2°C limit currently aimed at may produce increasing amounts of severe weather events and flooding from sea level rise.

Hothouse Earth is not inevitable, because there are political, economic, and technological strategies that can stabilize temperatures. But the authors of the article acknowledge that forestalling disaster will also require transformation of values, principles, and belief frameworks. So the problem of dealing with climate change is partly psychological.

The psychological project of getting people and governments to deal with the threats from climate change is both cognitive and emotional. The cognitive side of educating people about global warming requires attention to central concepts such as mechanisms, tipping points, and self-reinforcing feedbacks. These concepts are important for climate change in order to appreciate why the Earth is not getting warmer in an obvious, steady way.

Tipping points occur when slow gradual changes lead dramatically to rapid transformations. A psychological example is when a person becomes gradually more annoyed then suddenly explodes in fury. Similarly, gradual changes in global temperature that pass a tipping point can lead to cataclysmic climate events.

One of the reasons that quantitative changes can lead to large qualitative transitions is that there are feedback loops among factors such as ice sheets, forests, permafrost, and the jet stream. In psychology, the term feedback tends to mean comments that people receive from each other, as in "I appreciate your feedback about my presentation." But in climate science, feedback means that factors influence each other—for example, when melting sea ice warms temperature enough to melt the permafrost, which in turn warms temperature enough to melt more sea ice. This kind of interactive feedback is also common in human relationships, as when one person's kindness and affection for another can prompt reciprocal kindness and affection, producing a loop that eventually leads to a transition from liking to loving.

In addition to concept acquisition, psychology is relevant to understanding how people can change their beliefs. Climate scientists have collected an enormous amount of empirical evidence showing that global warming is occurring, that human production of greenhouse gases is responsible for warming, and that stopping production of greenhouse gases can prevent disasters. Psychology can help to understand the mental processes that lead to revisions and beliefs about global warming. Another major psychological concern about climate change is its likely effect on mental health, which is beginning to be studied.

Psychology also has an important role in understanding resistance to belief change about global warming. Emotion and motivation are major factors in explaining why many leaders in government and industry do not accept scientifically backed hypotheses about the causes and remedial measures for climate change. The Hothouse Earth hypothesis is scary, and the economic and political changes to prevent it are daunting. The motivations that people have to disbelieve that humans are responsible for global warming lead them to ignore relevant evidence, and sometimes not to think about the issue at all.

As the authors of the Hothouse Earth paper acknowledge, values are crucial to debates about how to deal with climate change. Values such as human survival, equality, and democracy are emotional mental states that can be understood as neural processes. So changing values can require both revising concepts such as equality and changing the emotional attachments that people have to them. Overemphasis on a narrow set of values such as individual freedom and economic growth can obscure values such as human survival and flourishing that are important for the long-term development of the inhabitants of our planet.

Another important transition in values requires people to think not only of current generations but also of many generations to come. If Hothouse Earth happens by the end of the century, billions of people not yet born will suffer enormously from problems such as flooding, famine, and intolerable temperatures. I argue in my forthcoming book, Natural Philosophy, that the reason for caring about future generations is the same as the reason for caring about people beyond your own self and family. Using empathy and imagination, we can appreciate that future people might end up suffering in ways that we would not want to suffer ourselves. Caring about future humans is crucial for taking the political and economic steps needed to prevent the development of Hothouse Earth.


Lewandowsky, S., Oberauer, K., & Gignac, G. E. (2013). NASA faked the moon landing—therefore,(climate) science is a hoax: An anatomy of the motivated rejection of science. Psychological Science, 24(5), 622-633.

Ranney, M. A., & Clark, D. (2016). Climate change conceptual change: Scientific information can transform attitudes. Topics in Cognitive Science, 8(1), 49-75. doi:10.1111/tops.12187

Steffen, W., Rockström, J., Richardson, K., Lenton, T. M., Folke, C., Liverman, D., . . . Crucifix, M. (2018). Trajectories of the Earth System in the Anthropocene. Proceedings of the National Academy of Sciences,

Thagard, P., & Findlay, S. D. (2011). Changing minds about climate change: Belief revision, coherence, and emotion. In E. J. Olsson & S. Enqvist (Eds.), Belief revision meets philosophy of science(pp. 329-345). Berlin: Springer.

Thagard, P. (2019). Natural philosophy: From social brains to knowledge, reality, morality, and beauty. Oxford: Oxford University Press.

Van Lange, P. A., Joireman, J., & Milinski, M. (2018). Climate change: What psychology can offer in terms of insights and solutions. Current Directions in Psychological Science, 27(4), 269-274.