Compared to coal, which generates almost half the electricity in the United States, natural gas is indeed a cleaner, less polluting fuel. But compared to, say, solar, it's filthy. And of course there is nothing renewable about natural gas.

Geoengineering - the deliberate, large-scale manipulation of the earth's climate to offset global warming - is a nightmare fix for climate change.

In reality, Republicans have long been at war with clean energy. They have ridiculed investments in solar and wind power, bashed energy-efficiency standards, attacked state moves to promote renewable energy and championed laws that would enshrine taxpayer subsidies for fossil fuels while stripping them from wind and solar.

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.

One of the big questions in the climate change debate: Are humans any smarter than frogs in a pot? If you put a frog in a pot and slowly turn up the heat, it won't jump out. Instead, it will enjoy the nice warm bath until it is cooked to death. We humans seem to be doing pretty much the same thing.

The coal industry is an even larger part of the Australian economy than it is of the American, and it has an enormous amount of political power.

Nowhere has the political power of coal been more obvious than in presidential campaigns.