Warren Buffett's big railroad buy is also a huge bet on coal

If the Sage of Omaha is truly an oracle of future returns and a leading indicator for where the market is going, it's hard not to think that U.S. carbon emissions will continue to grow apace and that the budding green revolution will be more bang than bucks.

Why? On Tuesday, Buffett paid a hefty 25 percent premium to acquire the remaining 77 percent interest in railroad giant Burlington Northern Santa Fe (BNI) that his company, Berkshire Hathaway (BRK.A), did not already own. The fate of Burlington Northern is closely tied to shipments of coal.