How does the carbon footprint for x amount of Bitcoin (in, say, $ terms), compare with the carbon footprint of both printing and maintaining a similar amount of traditional currency?
Not to mention losses due to counterfeiting and outright destruction.
And transportation.
Only three to eight percent of fiat currency is held in cash.
True, but that's still a substantial amount of physical stuff that needs to be made and maintained...
Also I wonder how it compares to the carbon footprint of the mining industry of gold.
Meh. Use it as a preheater for your furnace. Don't mine in the summer.