Why We Overestimate the Positive Impact of Our Actions on the Climate

Published on 3 Aug 2026

Carbon competence refers to the ability to accurately assess the impact of different individual actions on greenhouse gas (GHG) emissions. A high level of carbon competence enables people to identify the most effective ways to reduce emissions, both individually and collectively, thereby contributing to climate change mitigation. Yet several studies show that carbon competence remains limited across the general population, including among people who are highly concerned about environmental issues.

As a result, people tend to overestimate the climate impact of relatively modest actions, such as recycling or printing double-sided. While these behaviours are beneficial, their effect on greenhouse gas emissions remains limited. By contrast, people often underestimate the impact of far more effective actions, such as giving up air travel or reducing car use.

The most overestimated low-impact behaviours are, in order: recycling, using recycled materials, purchasing more energy-efficient household appliances, improving home insulation, and teleworking.

Thirty-two climate actions analysed

Based on a sample of nearly 3,000 participants, a team from UNIGE examined the psychological barriers that explain these misperceptions. The effectiveness of three measures designed to improve carbon competence was also tested.

“We selected 32 individual actions, ranging from low-impact behaviours to those with much greater environmental benefits. We then analysed how participants estimated the positive impact of these actions when adopted by an average person,” explains Mario Herberz, postdoctoral researcher at the Consumer Decision and Sustainable Behaviour Laboratory at the Faculty of Psychology and Educational Sciences of UNIGE, and first author of the study. “To our knowledge, this is the first study to examine such a broad range of actions with this level of detail.”

Two psychological biases

Among the 32 actions studied, the most overestimated low-impact behaviours are, in order: recycling, using recycled materials, purchasing more energy-efficient household appliances, improving home insulation, and teleworking. By contrast, the most underestimated high-impact behaviours include giving up air travel, living without a car, switching to an electric vehicle, avoiding long-haul flights, and purchasing renewable electricity.

According to the research team, this gap in carbon competence can be explained by two psychological biases: the ‘availability heuristic’, a mental shortcut whereby people judge an action as more effective if it easily comes to mind, and ‘motivated reasoning’, which serves to preserve a positive self-image. “In the first case, the more an action is present in the media or discussed at school, the more easily it comes to mind, and the more likely people are to consider it effective,” explains Mario Herberz. “In the case of motivated reasoning, individuals tend to believe that the actions they already engage in are more effective, because this perception allows them to preserve a positive self-image.”

The researchers also show that individuals with strong pro-environmental values tend to be overly optimistic and to overestimate the impact of environmental actions in general. By contrast, those with a stronger capacity to handle numbers tend to provide more accurate estimates and are less influenced by these biases.

The limits of ‘one-size-fits-all’ solutions

To correct these misperceptions, the research team tested several interventions. In particular, they assessed the effect of simply providing a list of high-impact actions on participants’ estimates of greenhouse gas emissions. They also examined whether participants could improve their estimates by relying on two indicators: the behavioural cost of an action (the more effort, time, or financial resources it requires, the more likely it is to have a high impact) and its social prevalence (the rarer it is within the population (e.g., the U.S.), the greater its potential to reduce carbon emissions tends to be).

“The results show that the effectiveness of these interventions varies considerably from one individual to another, particularly depending on their ability to use behavioural cost or social prevalence as a cue of an action’s actual impact,” reveals Mario Herberz. “The challenge is therefore to tailor awareness campaigns to different population profiles — which still need to be defined — in order to better correct these biases and encourage the adoption of climate actions and support for policies that are most effective in reducing greenhouse gas emissions.”