Bill Gates is a relative newcomer to the fight against global warming, but he's already shifting the debate over climate change.
Bloomberg's $50 million is not going to revolutionize the electric power industry. But his willingness to fight is already inspiring others to see Big Coal differently.
New York City Mayor Michael Bloomberg, who also happens to be the 10th richest person in America, with a personal fortune of some $18 billion, likes to pick a fight - especially fights where the line between good and evil is particularly stark.
