Among all the tests President Obama faced in his first term, his biggest failure was climate change.

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.

Some studies suggest that the Arctic Ocean may be ice-free by the end of the century.

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.

Bill Gates is a relative newcomer to the fight against global warming, but he's already shifting the debate over climate change.

Obama's record on climate issues is not all bad.

Ethanol doesn't burn cleaner than gasoline, nor is it cheaper.