I would be plausibly intrigued by a cryptocurrency where the proof of work is something (a) physically tangible and (b)…

I would be plausibly intrigued by a cryptocurrency where the proof of work is something (a) physically tangible and (b) positive, e.g. “I planted a tree: its GPS coordinates are X,Y: it can be monitored here: this coin will be deleted/garbage-collected if/when the tree dies”. https://t.co/oVa7M78c71

—Charlie Stross (@cstross)