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?
Well, actually bitcoin mining is not harming the environment. Bitcoin mining only produce heat from it, and cost electricity,
and not producing any waste. The only thing concern me about bitcoin mining is the asic company could mining btc secretly and monopolized the profit.