From the article I quoted:
"One user (@khannib) found that 10 years of Bitcoin mining has produced the equivalent energy consumption as all American cars in three or four days."
A least most of the electricity used in mining comes from clean or renewable energy sources, not producing dirty emissions that would require you to wash your car sooner than you would like too - you are essentially comparing apples and oranges.
I may be wrong but isn't most mining electricity still coming from traditional sources rather than solar, wind, and hydro.
America could easily cut down emissions if they had more public transport systems instead of everyone owning a car.