A currently popular proposal for fairly distributing emission quotas is the equal shares view, which holds that that emission quotas should be distributed to all human beings globally on an equal per capita basis. In this paper I aim to show that a number of arguments in favour of equal shares are based on a misleading analysis of climate change as a global commons problem. I argue that a correct understanding of the way in which climate change results from the (...) overuse of a global commons shows those who defend equal shares using commons arguments to be harbouring more controversial commitments than might at first appear. I then discuss two options for equal shares theorists who wish to maintain the view in the face of my critique, and attempt to show that one approach holds more promise than the other. (shrink)