U.S. counties where the population places a high value on purity also tend to have lower household carbon footprints, according to a new study. The findings call into question the assumption that purity is a conservative moral value, and suggest a strategy for tailoring climate change messages to local audiences more effectively.

In the study, researchers investigated geographical patterns of household carbon footprints and climate change attitudes through the lens of Moral Foundations Theory, which holds that people have deep intuitions about care, fairness, loyalty, authority, and purity that shape their moral judgements and political points of view.

Moral values are known to vary from place to place, as do environmental attitudes. Research has also shown a link between people’s moral values and their beliefs and actions around climate change. But few studies have investigated relationships between a community’s moral values and climate beliefs and actions at a collective level.

To explore this, researchers analyzed 106,465 responses to an online Moral Foundations Questionnaire collected between 2012 and 2018. They juxtaposed these results with data from opinion surveys including 12,061 participants conducted between 2008 and 2013, measuring beliefs about the reality, human causation, and negative impacts of climate change.

The researchers sorted their data by U.S. county and controlled for other variables such as the severity of local climate impacts, the education level and political leanings of the local population, and how urban or rural the county is.

Not surprisingly, the strongest influence on the prevalence of climate-friendly attitudes in a county is the political leaning of its residents. But the second-strongest influence is the degree to which the population embraces fairness values, the researchers report in the journal PNAS Nexus.

Counties with high levels of education and those where purity values predominate are also more likely to embrace climate-friendly attitudes. Meanwhile, conservative counties, counties where authority values are prevalent, and richer counties show less support for climate-friendly attitudes.

The researchers also analyzed the relationship between county-level moral values and household carbon footprints, using modeled carbon footprint data provided by the University of California, Berkeley CoolClimate Network. After the researchers controlled for factors such as county political leanings, green attitudes, and climate change impacts, the prevalence of purity norms emerged as the factor with the strongest relationship to smaller household carbon footprints.

“While political orientation strongly predicts environmental attitudes, moral values appear to be a more important factor in predicting carbon footprints,” the researchers write.

Meanwhile, counties where authority and care values are prevalent, as well as more conservative ones, tend to have larger household carbon footprints.

Across both analyses, “counties where purity and fairness norms are prevalent show higher environmental concern and lower emissions, while those where authority norms dominate tend to have higher emissions and less green engagement,” the researchers write.

Although purity is normally thought of as a conservative value, the findings suggest that liberals may value purity in the sense of keeping the Earth sacred and unharmed.

This, in turn, could aid in the design of more effective climate action strategies that tap into the moral values held by different communities. “Overall, framing environmental action in terms of purity or sanctity (e.g. keeping the Earth pure and untainted) might be an effective strategy in certain areas, especially those where these norms are strong,” the researchers write.

Source: Karimi-Malekabadi F. et al. “A value-based topography of climate change beliefs and behaviors.” PNAS Nexus 2025.

Image: Based on an image by Paul Downey via Flickr.