Ethics, Policy and Environment Vol. 14, No. 1, March 2011, 31–33 OPEN PEER COMMENTARY Beware of Averages: A Response to John Nolt’s ‘How Harmful are the Average American’s Greenhouse Gas Emissions?’ RONALD SANDLER Department of Philosophy & Religion, Northeastern University, USA In ‘How harmful are the average American’s greenhouse gas emissions?’ John Nolt (2011) correctly points out that the claim that an individual’s contribution to total atmospheric greenhouse gas levels and associated harms is negligible is usually made without adequate evidence (Jamieson, 2007; Sandler, 2010; Sinnott-Armstrong, 2005). The percentage of total emissions that an average American is responsible for is, in large part, an empirical question. 1 Nolt attempts to calculate this percentage. Nolt also attempts to calculate the total harm that will be caused by anthropogenic global climate change. Given these values he believes that he can calculate, in a rough but informative sense, the harm caused by the average American’s greenhouse gas emissions. This, in turn, provides a sense of the ‘moral significance’ of an average American’s ‘complicity in a greenhouse-gas-intensive economy’ (Nolt, 2011, pp. 3–10). In this commentary, I raise concerns about Nolt’s approach to determining the harm associated with an average American’s emissions. How much harm an average American’s emissions cause is not, as in Nolt’s calculation, the amount of total harm caused by climate change times the portion of total anthropogenic emissions for which an average American is responsible over her lifetime. (On Nolt’s calculations this is, roughly, somewhere in the range of 2–4 billion sufferings/deaths times, roughly, one two-billionth of total emissions—that is, 1 or 2 harms.) Rather, it is the amount of harm caused by anthropogenic climate change minus the amount of harm caused by anthropogenic climate change if total atmospheric levels of CO 2 emission were reduced by the amount of the lifetime emissions of an average American. Let us take Nolt’s figure for an average American’s greenhouse gas emissions, 1584 metric tons. To determine how much harm is caused by those emissions, we would need to know the harm caused by climate change on the scenario when those emissions occur and the harm caused Correspondence Address: Ronald Sandler, Department of Philosophy, 371 Holmes Hall, Boston, MA 02115, USA. Email: r.sandler@neu.edu 2155-0085 Print/2155-0093 Online/11/010031–3 ß 2011 Taylor & Francis DOI: 10.1080/21550085.2011.561591