I think our main problem is the huge electricity expense induced by mining and its noxious effect on the climate. This is, to my mind, the only serious argument against Bitcoin.
Alleviating the electricity expense should be one of our priorities. If we do not do it for the sake of the Earth (which we really should) we should at least do it selfishly because governments will not tolerate this forever and they will be right. The more the exchange rate increases, the worse it gets, of course.
Some solutions exist though: first there is proof-of-stake, of course. This technology may be too young to be deemed reliable enough but we should at least start considering it.
If we do not like proof-of-stake I think we could drammatically decrease the electricity expense by stopping monetary creation now. Nowdays Bitcoin is famous enough to remain secure even if miners earned transaction fees only. And if as a whole there are 16.5 M coins instead of 21 M, this does not make much of a difference. That is even good for holders. To make miners agree with that solution, they must be compensated for their lost income. More precisely, active miners must be compensated because they have already bought ASICs. Futures miners do not need to be compensated. Since mining is a competitive industry, future miners will make no profit on average, whatever the reward scheme. To compensate active miners we could decide that the next 2016 blocks yield, say, 100 new coins and then 0 forever. Everybody would win and the Earth above all!
There are probably many other solutions and I wish the community cared a little more about this fundamental issue.
I don’t think that bitcoin has nothing to do with global warming as bitcoin and global warming are entirely two different topics but yes I heard this rumours too about bitcoin then in the coming decade bitcoin is going to use double the amount of electricity as used by the entire world then in turn bitcoin could be responsible for the global warming but I want to say that just once think about this that is it ever possible that bitcoin is consuming that amount of electricity, all I think is that this is a rumour only spread by one of the bitcoin hater.