'Invisible substances': Can we trade them? Of course we can...

Today I heard the leader of the federal opposition, Tony Abbott, describe the government's proposed change to an emissions trading scheme, as:

A market in the non-delivery of an invisible substance to no-one.

This position is not new, and Mr Abbott has for some years described carbon in terms such as an 'invisible, odourless, weightless, tasteless substance'. Regardless of the science or the economics involved in characterising carbon and the effectiveness of a carbon market per se, what interests me is the problematising of a market in an 'invisible substance'. It also surprises me in light of the law's unambiguous acceptance of intangibles as property, which supports the commodification and therefore marketisation of a host of 'invisible, odourless, weightless, tasteless'...non-substances.