Mark Ruffalo, aka the Incredible Hulk, is the natural gas industry's worst nightmare: a serious, committed activist who is determined to use his star power as a superhero in the hottest movie of the moment to draw attention the environmental and public health risks of fracking.

Extracting oil from the tar sands is a nasty, polluting, energy-intensive business.

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.

When it comes to climate and energy, Gates is a radical consumerist. In his view, energy consumption is good - it just needs to be clean energy.

One thing you can say about nuclear power: the people who believe it is the silver bullet for America's energy problems never give up.

In reality, studies show that investments to spur renewable energy and boost energy efficiency generate far more jobs than oil and coal.

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.