At the end of the day, no amount of investing, no amount of clean electrons, no amount of energy efficiency will save the natural world if we are not paying attention to it - if we are not paying attention to all the things that nature give us for free: clean air, clean water, breathtaking vistas, mountains for skiing, rivers for fishing, oceans for sailing, sunsets for poets, and landscapes for painters. What good is it to have wind-powered lights to brighten the night if you can't see anything green during the day? Just because we can't sell shares in nature doesn't mean it has no value.

If you don't have an ethic of conservation, you basically have a license to drive a Hummer through the Amazon.

If I were advising President Obama, since he's the one running, I would have made his campaign very simple. I promise that in four years, I will get more Americans, as many as I possibly can, the opportunity and access to some form of post-secondary education. I want more of them to graduate high school with the skill-set of post-secondary education and I want more of them to be able to obtain that post-secondary education. This is the only way we are going to close the income gap.

Pessimists are usually right and optimists are usually wrong but all the great changes have been accomplished by optimists.

Even if America tomorrow - and it won't happen overnight - but if we did reduce our demand for gas and natural gas and crude oil by a significant degree, that does have an exponential effect on producers in the Middle East, everything else being equal. But if China's demand is growing and India's demand is growing, they are not going back.

If e-mail had been around before the telephone was invented, people would have said, 'Hey, forget e-mail! With this new telephone invention I can actually talk to people!'.

Remember, the difference between the world frozen over, in an ice ball, and the warming period we're in now is just 6 degrees centigrade. A change of just 1 degree can have a huge effect.