“unlike traditional commodities, which sometimes during the course of their market exchange must be delivered to someone in physical form, the carbon market is based on the lack of delivery of an invisible substance to no one.”
Mark Schapiro (apparently) in Harper’s in early 2010 [I found it here https://www.integrity-research.com/wanted-independent-research-to-assess-carbon-offsets/ but the link back to Harper’s is broken, as is a similar link in another piece quoting it; perhaps Harper’s pulled it; this piece attributes it to Mark Schapiro: https://www.reddeeradvocate.com/columns/air-travel-major-contributor-to-climate-change/].