Nolt climate change calculation

Calculating individual contributions to climate change by Anton Eriksson

While there is consensus about the causes of climate change, it’s difficult to work out what individuals can do to fight it. Here, Grantham Scholar Anton Eriksson unpicks John Nolt’s climate change calculations.

Anton Eriksson
Anton Eriksson

The scientific community almost unanimously agrees that human-induced climate change is happening. And they agree that we need to reduce our global greenhouse gas emissions in order to mitigate it.

Individual impacts on climate change

Some people take this to imply that we each have reason to act against climate change. Perhaps we should eat less meat, choose public transportation, or otherwise try to reduce our individual emissions of greenhouse gasses.

Others however, argue that individual efforts to combat climate change are futile. Since individual actions have such small impacts, the reasoning goes, they make no global difference. For example, it’s not as if my purchase of one steak causes the sea levels to rise.

Overall, we need to address this disagreement in order to take effective action on climate change.

How harmful are the average American’s greenhouse gas emissions?

John Nolt authored a paper on the harmful contributions individuals make to climate change. This paper ‘How harmful are the average American’s greenhouse gas emissions?‘ was the focus of our Journal Club.

In the paper, Nolt estimates of how much harm is caused by the average American’s emissions. By doing so, he wants to defend the claim that individuals do cause harm through their emissions.

Specifically, Nolt argues that an average American, through their lifetime emissions, causes the death and/or suffering of 1 or 2 future people. To reach this figure, Nolt takes the total American greenhouse gas emissions and divides it by the US population. This figure is then related to the American share in the total amount of harm caused by climate change. And then this is again divided by the US population.

Naturally, all of these steps rely on a number of contentious assumptions. Some of these were the focus of our discussion of Nolt’s paper.

Issues with Nolt’s paper

The first cohort of Grantham Scholars
The Grantham Scholars of 2015.

One issue raised by other Grantham Scholars was that by dividing the total emissions of the US by the number of Americans, Nolt fails to take into account how emissions are distributed among them. Some Americans are bound to have huge emissions footprints, while others have small ones. It can therefore be asked how useful such an estimate is for the purpose of showing that particular individuals make a difference to climate change.

Another topic that we discussed was that any estimate of the total harm caused by climate change will be problematic. Since much of the harm and suffering which results from climate change will take place in the future, the figures used by Nolt can at best be seen as very crude approximations.

In sum, the general sentiment of the discussion seemed to be that Nolt’s project, although flawed and relying on a set of problematic assumptions, might still have some merit. Some of the points that Nolt’s paper provoked might come to guide further research on the topic. The Grantham Scholars all seemed to agree that the topic of individual responsibility for climate change is an important one. A reliable estimate of the individual impacts of everyday actions might be a powerful tool to engage people to take action against climate change.


Journal Club is meet up of Grantham Scholars to discuss publications from a multidisciplinary perspective. It is part of the Grantham Scholar training programme.

Edited by Claire Moran. Photo by RODNAE Productions from Pexels.