H. Orri Stefánsson is Associate Professor (Docent) of Practical Philosophy at Stockholm University, Pro Futura Scientia Fellow at the Swedish Collegium for Advanced Study, and Researcher and Advisor at the Institute for Futures Studies. When individuals cause greenhouse gas (GHG) emission – for instance, by going for a Sunday drive – they risk harming others. Imposing such risk on others is unjust unless in special circumstances that do not seem to apply to individuals’ GHG emission. So, it might seem that justice imposes a very strict demand: we are not to emit any GHG (over and above what is necessary for our sustenance). Some philosophers (e.g., John Broome and William MacAskill) have however argued that meeting this demand is not as hard as it might seem: by offsetting the GHG emission we cause, we do not harm anyone, they argue, and therefore we act justly. One problem for this view is that we have reason to believe that when we emit and offset, the people who benefit from our offsetting are different from those who are harmed by our emission, which means that offsetting does not compensate the victims of our emission. Another problem is that offsetting is not a very efficient way to do good; for instance, the amount it takes to offset an individual’s lifetime emission can be used instead to almost certainly save more than one child’s life (unlike the same amount spent of offsetting). In this talk I consider deontic, consequentialist, and contractualist moral principles that might apply to individuals’ offsetting, and I argue that the aforementioned problems make it hard to find a principled moral justification for the practice of emitting and offsetting. Some moral principles imply that individuals act unjustly by emitting and offsetting, while other moral principles imply that instead of offsetting one should give to charities that do good more efficiently.