There are already plenty of incentives for improving energy generation, reducing waste, and getting better at efficient delivery: people are willing to spend money for electricity for useful purposes other than speculation.

If anything, bitcoin mining is a disincentive in making a more energy efficient green economy: instead of reducing waste and reducing power production as needed, we now have a way to turn excess power production into money directly. While a carbon tax could have shut down a coal plant, now the coal plant could instead get a bitcoin mining rig and power that, as long as the carbon tax is lower than the (extremely volatile) value of bitcoin.

To avoid the most apocalyptic effects of global warming, we have to close down most fossil-fuel based energy generation today, literally. Bitcoin is actively working against that by driving up the price of electricity to fuel a speculative bubble.