We know the rate at which bitcoin are mined, and we know exactly how much a bitcoin is worth, so it is straightforward to calculate how much money the miners are making -- namely, 17 billion USD per year at the current price of bitcoin. Since there are no barriers to entry to becoming a miner, we can expect that the effort spent on mining to match the rewards from mining almost exactly (since bitcoin miners are economically rational). We don't know what fraction of that $17 billion of effort (spending) consists of electricity, but basically all spending damages the environment. If some miner for example decides to pay researchers to come up with a more efficient mining algorithm, well, it takes a lot of carbon emissions (and other environmental harms) to raise, educate, feed and otherwise maintain a researcher. (It takes a lot of carbon emissions to raise, educate and maintain any person, even Greta Thunberg.)
If the price of bitcoin were to double, the (collective) rewards to mining double, too, and so does the environmental damage. In about 4 years, the reward for mining a block is scheduled to halve, and the environmental damage will at that time be about half of what it is now (a few months after the previous halving) provided the price of bitcoin does not change. All the miners know exactly when the reward is going to halve, so as the halving-date approaches, about 4 years from now, miners will invest less and less in mining hardware and other capital improvements, which "smooths out" the damage so that it decreases somewhat smoothly between now and then instead of suddenly halving on the day the reward halves.
If the price of bitcoin were to double, the (collective) rewards to mining double, too, and so does the environmental damage. In about 4 years, the reward for mining a block is scheduled to halve, and the environmental damage will at that time be about half of what it is now (a few months after the previous halving) provided the price of bitcoin does not change. All the miners know exactly when the reward is going to halve, so as the halving-date approaches, about 4 years from now, miners will invest less and less in mining hardware and other capital improvements, which "smooths out" the damage so that it decreases somewhat smoothly between now and then instead of suddenly halving on the day the reward halves.