It's not insignificant. Bitcoin mining already consumes as much energy annually as Denmark – that means the entire country, heating, cooling, industry, everything:
https://arstechnica.com/tech-policy/2017/12/bitcoins-insane-...
https://arstechnica.com/tech-policy/2017/12/bitcoins-insane-...
If websites begin to crowdsource mining on their visitors' PCs using JavaScript, the energy consumption will be even higher.
Let's optimize the real stuff, not some trivialities (like the Christmas lights in the USA pointed out as a reply).
There's 24/7 AC in USA and China in the masses. There's Brazilian and Argentinian agriculture removing rainforests to grow food for the USA or EU that grows cattle. (EU takes unbelievable amounts of rainforest grain/legumes to feed its livestock, an absolute travesty and hipocrisy)
The footprint of these developments is insanely large, yet somehow coin mining is an issue.
We could then jump to optimize the Internet infrastructure too, despite being 1-2% of CO2 equivalent footprint.
Yes, I understand coin mining seems a bit useless but I'm pretty sure heating and cooling is wasted in magnitudes more amounts, being applied in badly designed buildings, or cooling the streets of Las Vegas.
Can it be compared with other Internet services? How much electricity does Facebook consume, for example? What about internet advertisements?
Or 3,5 times what Amazon US-East cluster consumes: https://datacenterfrontier.com/amazon-approaches-1-gigawatt-...
32tWh/yr means roughly 3,6GW, which is output of 1-2 average nuclear power plants.
If we're going to soon need dozens of nuclear reactors to power cryptocurrencies, that's worth discussing at least. You can't brush it away as something insignificant in the grand scheme of things.
Let's say a reactor works for 10 years.
That would give $32,760 billion in trade, and reactor cost would be 0.833% of that.
Not a big fee if you ask me.
Of course, if cryptocurrencies would scale so they become significant between other trades, we can't just built thousands of nuclear reactors. This is where proof of stake will come into play.
https://en.wikipedia.org/wiki/Nuclear_power_phase-out
Reactors are being built primarily for heating and cooling, and eventually vehicle charging.