IF you think that humanity/ energy usage is a bad thing. Specifically when it comes to carbon emissions. Then I think a case can be made that bitcoin is negative through that framing.
I disagree with it but I do believe bitcoin will lead to more energy expenditure per capita globally which likely means more C02 released.
I don’t buy that C02 is really an issue but if you’re someone who does then that argument can be a compelling one.
One of the things I don’t like about the energy argument is that it ignores how much energy the present system uses. That just gets brushed off. And arguably, the present system is less efficient because the energy is generated specifically to run it, whereas you can plop a mining facility in an area where energy is being generated for something else, but in excess and with that excess otherwise going to waste.
That’s why I don’t make that argument in my hypothetical case against it.
I’m saying that after those inefficiencies are cleaned up by bitcoin, energy expenditure per capita will begin to follow the Henry Adams curve again. 
I’d still present “and that’s true for everything else” as a counter.
It’s not a great counter when the current system is clearly limiting the amount of energy expenditure per capita with all of its inefficiencies. Because capital allocation can’t be done effectively a lot of things that would otherwise be built, aren’t getting built because fiat puts productive capital in a wood chipper.
So, I’m one of the people who are convinced that CO2 is a problem. As in, it’s an existential threat to human civilisation. Not the planet, mind you, the planet will be fine.
But that doesn’t make me a Bitcoin hater. See, I don’t believe that energy use is the problem, it’s the mode of generation. When I switch on my laptop, it doesn’t start spewing out CO2.
I believe that the idea to start regulating what energy can be used on is a very slippery slope. Ok, let’s assume that a censorship resistant, global internet money is not worth it (I very much think it is). Why would gaming be exempt? Why would the energy spent in data centres running the ads industry be exempt?
The thing is even if you aren’t directly producing C02 when you turn the laptop on, you are at some point in the supply chain.
Mining, processing the ore, transporting the materials, producing the energy your laptop uses, etc… at some point C02 will be released.
Even if you have an all nuclear grid there are a bunch of things that go into supporting those plants that still require C02 to be produced. (Chemicals needed to support operations must be made, materials for the plants to stay operational must be made, distribution lines must have trees cleared, etc…)
I haven’t seen in any weather patterns that comes close to an existential threat to humanity.
It seems to me there is a contradiction in your logic, if C02 isn’t an existential threat to the biosphere then it isn’t to humans either. I put my money on our ability to engineer solutions even if there are drastic changes to the climate.
C02 is plant food, all it’s done so far is make it easier to grow crops and it’s made the world a little greener 🤷♂️
Regarding the laptop. I realise full well how the supply chain produces CO2, but that’s exactly the point I’m trying to make. In my opinion it’s not the use of energy that’s the problem. Energy generation might be, depending on mode of generation.
Concrete buildings are not the problem, coal being burned in kilns is the problem. I find this distinction really important. By focusing on the wrong thing we’re going to come up with the wrong solutions. Such as banning concrete. Or banning Bitcoin mining.
That’s the thing though, if you want a modern life you will release C02. They are inexorably linked.
You either reduce human population to pre 1900s levels or you continue to use hydro carbons. There is no alternative. 
Regarding CO2 and climate. It so happens that I’ve spent a part of my career working directly with climate related data. Think glacier extent, sea ice extent, sea surface temperature, etc. To me anthropogenic climate change is just a fact.
Plants will be fine, but humans and especially human civilisation are finicky things. Healthy humans start dropping like flies in wet bulb temperature of 35 Celsius. Currently that’s pretty rare, but it’s going to become more and more prevalent during this century.
On top of that add water stress, drought, and rising sea level, and you easily get to around a quarter of humanity living in areas that are going to become increasingly inhospitable. This won’t be a huge problem for, say, the United States. Americans can just move more inland and more north. Also, rich societies can find technological solutions to keep living in inhospitable environments.
The rest? The rest will try to move. This will lead to conflict and the fall of any semblance of international order. Because the places where these people will move to will become increasingly hostile to the newcomers as their numbers soar.
Cold kills roughly 20 times more people every year than heat does.
Humans do fine in the heat, they don’t do well at all in the cold. The dropping like flies claim is not backed up by any evidence. It’s not rare because the earth isn’t hot, it’s rare because humans sweat lol.
Sea levels have not risen at all in the past 200 years and they are certainly not rising at anything close to unmanageable levels if they are rising at all.
I work with this data on a regular basis in my day job as well so the argument from authority doesn’t really work on me.
The catastrophism around anthropogenic climate change is completely unjustified.
Lastly C02 tends to lag temperature changes when you look at the last 800,000 years of ice core data so it’s clearly not the primary driver of global temperature swings. 
You do know why wet bulb temperature of 35 becomes dangerous, right?
Because sweating stops working as a heat management mechanism due to physics.
Yes I am, and yet humans still find ways to cool off in hot areas.
We have been living in every climate of the world for at least 15,000 years. Likely much longer, and even with all of our modern inventions. Cold still kills 20 times more people than heat does.
It’s much easier to escape the heat in some shade than it is to escape the cold when you have no source of heat.
There is no data to date that shows that the earth warming by a degree or two over the next century will lead to far more deaths from heat.
