This argument certainly has some validity (see also Ensmenger's project to understand the environmental role of computing in general: http://homes.soic.indiana.

This argument certainly has some validity (see also Ensmenger's project to understand the environmental role of computing in general: http://homes.soic.indiana.edu/nensmeng/enviro-compute/dirtybits.html http://homes.soic.indiana.edu/nensmeng/enviro-compute/dirtyb...). However, it only goes so far, since other consensus mechanisms could have lower energy requirements. Proof of stake, e.g., (if it ever gets off the ground) could change the game. Similarly, if the economics of proof of work were re-jigged, it isn't impossible that the energy required for mining could be dramatically lowered. But, as it stands, Bitcoin, in particular, has a shamefully large environmental footprint.