Share prices of major coal mining companies in the United States have collapsed in the last two years. Investors have lost billions. The lack of any solution to the high levels of climate pollution from coal burning is dimming the industry prospects for a growing number of investors. Amazingly this gutting of market capitalization over the last two years has happened while US coal production fell just 6%. It's not today's relatively small decline that has spooked investors. Instead it is a rapid change in what the future looks like for American coal. Just a few years ago the accepted future was one of decades of growth. This has quickly morphed in many investors' minds into a scenario of long term decline. That popping sound is not from champagne corks anymore.