The habits of the West in terms of consumption.

We finally know where the red line for climate really is. After the rapid melt of arctic ice in the summer of 2007, our best scientists, led by NASA's Jim Hansen, went back to work and produced a series of papers showing that with more than 350 ppm (parts per million) of carbon dioxide in the atmosphere, we couldn't have a planet "similar to the one on which civilization developed and to which life on earth is adapted."

I don't spend a huge amount of time fixated on climate denial because I don't think that their objections, though sometimes couched in science, are based in science. I think they're based in ideology. And I don't think there's anything you can do.

For the first time in 150 years, the USDA reported there were more farms in America, not fewer. That has to make you happy.

If there's horrible flooding in Pakistan or a horrible heat wave in Texas, we're no longer able to call it an act of God, or a natural disaster, or something like that, the way we could have through all of human history until 35 or 40 years ago.

We just see a sort of cascading amount of data of the damage that is being done by those increased temperatures.

All the things that we've done as a species have had a limited scope. We're talking about melting the ice caps, raising the level of the seas dramatically, changing the distribution of every other species on Earth, perhaps wiping out one-third or half of them. The changes at work are geologic in scale. The level of change required to deal with it is enormous, too. It will require change in every country. It will require a degree of global cooperation that we haven't seen before.