Market-based solutions have become an important focus for international strategies to reduce emissions of carbon dioxide. The commodification of carbon through markets, however, raises a number of questions about the ethics and justice implications of these approaches. They are tied up in a calculative, managerial approach to the environment, which looks for cost-effectiveness, just allocations of carbon allowances and equitable international frameworks. In this paper and using an extended case study of personal carbon trading I argue that current debates have insufficiently focused on the ethical assumptions that underlie these solutions. A universal system of carbon monitoring may not offer the kinds of political debates and imaginations of the good life that will be required for a more thoroughly participatory engagement in climate change debates. Opening up these broader ethical questions is a starting point for a renewed realisation of climate change as being as much of a cultural, moral issue as a technical challenge.