There is reason to be concerned about the environmental impact of digital currencies. As the popularity of cryptocurrencies such as bitcoin and ether has grown, so has the number of mining operations around the world. Each individual mining rig necessitates massive amounts of computational power, which necessitates requires large amounts of electricity.
What's important to remember is that the value of mining for a cryptocurrency almost always outweighs the real-world cost of completing that mining operation.
Furthermore, many cryptocurrencies, including bitcoin, have established hard limits on the total number of tokens that can be mined. Individuals will no longer be able to mine for new tokens or coins after this point, and the costs of the computational power required to mine that currency will be dramatically reduced.
Don't forget that the modern financial and banking system, from office lights to computer servers to electronic payment networks, consumes a lot of electricity on a daily basis.
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