Offsetting and Past Emissions

Abstract

Our past emissions continue to do harm. What are the moral implications of this fact? In this paper I argue that the long atmospheric lifetime of carbon dioxide in particular has profound impacts on our justice-based climate duties. It necessitates reaching the point of ‘lifetime net-zero’ emissions rather than just ‘present net-zero’ emissions. Since for almost all of us this is only possible by achieving ‘net-negative’ carbon footprints for a period of time, and we can only go ‘net-negative’ by offsetting, it implies a justice-based duty to offset. I furthermore argue that while reaching ‘lifetime net-zero’ is demanded by a duty of justice to harm as little as possible, there is no way to fully stop harming by emitting once one has emitted in the past.