A lot has been said about mining and about the electricity consumption of the activities related to bitcoin mining. However, I have thought of the alternatives and how other systems produce not just energy waste, but also plenty of useless work and "human waste".
To have a network that can ensure the completeness of transactions, the global accessibility and all the features that bitcoins, and many alts, have at the moment, would probable produce a huge carbon footprint. Just think of the VISA system or the banking system... the amount of people working on it, the waste of commuting to works, the infrastructure.
Thinking of all that, would you still say Bitcoin is bad for the environment?
Then start finding or sourcing out an alternative source of electricity such as putting mining farm in an open field in which they can cater establishing a solar panel farm just to sustain their environmental source of electricity so that they will not have to use that much of their money paying for a large electricity bill to support the operating power for mining of Bitcoin. Also, there are already lots of sources that have already proven and tested in which I think thry can already afford to purchase for the reason that it is also for their own sake.