In my opinion, mining btc has an impact with respect to power consumption and this will increased the fossil fuel consumption. Fossil fuels are generating more heat and pollution to the environment. Renewable source of energy should be developed further to help lessen the effects of global warming.
Then there must be a regulations not just on bitcoin mining but also to those establishments who are still using fossil fuel, because they tend to be more harmful than bitcoin mining. The ugly side of bitcoin is not just about the mining but also those who are using it because people are the one who controls it and used it into bad things for their own sake. If we want to help the environment then we must start on our own little way and always be responsible wherever you go.