Calculating individual contributions to climate change: Journal Club with Anton Eriksson

While there is broad consensus about the causes of climate change, it’s more difficult to work out what measures individuals can take to fight it. In this blog post, Grantham Scholar Anton Eriksson unpicks the climate change calculations that he discussed with his fellow PhD students during one of their regular Journal Club sessions.

This week’s paper

How harmful are the average American’s greenhouse gas emissions?‘ by J. Nolt

Anton Eriksson
Anton Eriksson

The scientific community almost unanimously agrees that human-induced climate change is happening and that we need to reduce our global greenhouse gas emissions in order to mitigate it. 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—it’s not as if my purchase of one steak causes the sea levels to rise. This seems like a serious worry that we might need to address in order to get people to take effective action on climate change.

One contribution to this debate has been given by John Nolt, who authored a paper on the harmful contributions individuals make to climate change. This paper was the focus of this week’s Journal Club.

In the paper, Nolt seeks to produce an estimate of how much harm is caused by the average American’s greenhouse gas emissions. By doing so, he wants to defend the claim that individuals do, in fact, cause harm through their emissions. More precisely, he argues that an average American, through their lifetime emissions, causes the death and/or suffering of one or two future people. This figure is the result of a calculation whereby 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, which is then 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 the discussion of Nolt’s paper. 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 very big emissions footprints, while others have very 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.