The most popular and most valuable cryptocurrency is also the least eco-friendly - data shows that Bitcoin mining generates the same amount of carbon emissions as the entire country of Thailand. According to nonprofit Fair Planet, 96 million tons of carbon dioxide emissions come from Bitcoin mining every year. Now, a consortium of climate activist groups is calling on the Bitcoin industry to cut its energy use by making changes to its software code. Michael Brune, former executive director of the Sierra Club, joins Cheddar News' Closing Bell to discuss.