Obama wants to be thought of as the president who freed us from foreign oil. But if he doesn't show some political courage, he may well be remembered as the president who cooked the planet.

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.

Americans don't pay much attention to environmental issues, because they aren't sexy. I mean, cleaning up coal plants and reining in outlaw frackers is hugely important work, but it doesn't get anybody's pulse racing.

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.

Have we failed to slow global warming pollution in part because climate and environmental activists have been too polite and well behaved?

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

Australia is the only island continent on the planet, which means that changes caused by planet-warming pollution - warmer seas, which can drive stronger storms, and more acidic oceans, which wreak havoc on the food chain - are even more deadly here.

With nine degrees of warming, computer models project that Australia will look like a disaster movie. Habitats for most vertebrates will vanish. Water supply to the Murray-Darling Basin will fall by half, severely curtailing food production.

In any crass political calculation, drilling for oil will always win more votes than putting a price on carbon. But if I recall what I was taught in fifth-grade American government class, we elect presidents to do more than crass political calculations.

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.