The personal carbon footprint of the richest people in society is grossly underestimated, both by the rich themselves and by those on middle and lower incomes, no matter which country they come from. At the same time, both the rich and the poor drastically overestimate the carbon footprint of the poorest people.

An international group of researchers, led by the Copenhagen Business School, the University of Basel and the University of Cambridge, surveyed 4,000 people from Denmark, India, Nigeria and the United States about inequality in personal carbon footprints—the total amount of greenhouse gases produced by a person's activities—within their own country.

Although it is well-known that there is a large gap between the carbon footprint of the richest and poorest in society, it's been unclear whether individuals were aware of this inequality. The four countries chosen for the survey are all different in terms of wealth, lifestyle and culture. Survey participants also differed in their personal income, with half of participants belonging to the top 10% of income in their country.

The vast majority of participants across the four countries overestimated the average personal carbon footprint of the poorest 50% and underestimated those of the richest 10% and 1%.

However, participants from the top 10% were more likely to support certain climate policies, such as increasing the price of electricity during peak periods, taxing red meat consumption or subsidizing carbon dioxide removal technologies such as carbon capture and storage.

The researchers say that this may reflect generally higher education levels among high earners, a greater ability to absorb price-based policies or a stronger preference for technological solutions to the climate crisis. The results are reported in the journal Nature Climate Change.

Although the concept of a personal carbon or environmental footprint has been used for over 40 years, it became widely popularized in the mid-2000s, when the fossil fuel company BP ran a large advertising campaign encouraging people to determine and reduce their personal carbon footprint.

"There are definitely groups out there who would like to push the responsibility of reducing carbon emissions away from corporations and onto individuals, which is problematic," said co-author Dr. Ramit Debnath, Assistant Professor and Cambridge Zero Fellow at the University of Cambridge. "However, personal carbon footprints can illustrate the profound inequality within and between countries and help people identify how to live in a more climate-friendly way."

Previous research has shown widespread misperceptions about how certain consumer behaviors affect an individual's carbon footprint. For example, recycling, shutting off the lights when leaving a room and avoiding plastic packaging are lower-impact behaviors that are overestimated in terms of how much they can reduce one's carbon footprint. On the other end, the impact of behaviors such as red meat consumption, heating and cooling homes, and air travel all tend to be underestimated.

However, there is limited research on whether these misperceptions extend to people's perceptions of the composition and scale of personal carbon footprints and their ability to make comparisons between different groups.

The four countries selected for the survey (Denmark, India, Nigeria and the US) were chosen due to their different per-capita carbon emissions and their levels of economic inequality. Within each country, approximately 1,000 participants were surveyed, with half of each participant group from the top 10% of their country and the other half from the bottom 90%.

Participants were asked to estimate the average personal carbon footprints specific to three income groups (the bottom 50%, the top 10%, and the top 1% of income) within their country. Most participants overestimated the average personal carbon footprint for the bottom 50% of income and underestimated the average footprints for the top 10% and top 1% of income.

"These countries are very different, but we found the rich are pretty similar no matter where you go, and their concerns are different to the rest of society," said Debnath.

The researchers also looked at whether people's ideas of carbon footprint inequality were related to their support for different climate policies. They found that Danish and Nigerian participants who underestimated carbon footprint inequality were generally less supportive of climate policies. They also found that Indian participants from the top 10% were generally more supportive of climate policies, potentially reflecting their higher education and greater resources.

"Poorer people have more immediate concerns, such as how they're going to pay their rent, or support their families," said first author Dr. Kristian Steensen Nielsen from Copenhagen Business School. "But across all income groups, people want real solutions to the climate crisis, whether those are regulatory or technological. However, the people with the highest carbon footprints bear the greatest responsibility for changing their lifestyles and reducing their footprints."

After learning about the actual carbon footprint inequality, most participants found it slightly unfair, with those in Denmark and the United States finding it the most unfair. However, people from the top 10% generally found the inequality fairer than the general population, except in India. "This could be because they're trying to justify their larger carbon footprints," said Debnath.

The researchers say that more work is needed to determine the best ways to promote fairness and justice in climate action across countries, cultures and communities.

"Due to their greater financial and political influence, most climate policies reflect the interests of the richest in society and rarely involve fundamental changes to their lifestyles or social status," said Debnath.

"Greater awareness and discussion of existing inequality in personal carbon footprints can help build political pressure to address these inequalities and develop climate solutions that work for all," said Nielsen.