Probably nothing that we have ever managed to do quite equals the basic undermining of the physical stability of the planet on which most of the world's poor people depend.

The real negotiation is between humans on the one hand and chemistry and physics on the other. And chemistry and physics, unfortunately, don't bargain.

In 50 years, no one will care about the fiscal cliff or the Euro crisis. They'll just ask, "So the Arctic melted, and then what did you do?"

But tolerance by itself can be a cover for moral laziness.

In the States, I think, the syllogism goes like this: 'free markets solve all problems. Free markets aren't solving global warming, QED global warming is not a problem'. It's not a very good syllogism but it's emotionally comforting if you're in that world.

We believe that we live in the 'age of information,' that there has been an information 'explosion,' an information 'revolution.' While in a certain narrow sense this is the case, in many important ways just the opposite is true. We also live at a moment of deep ignorance, when vital knowledge that humans have always possessed about who we are and where we live seems beyond our reach. An Unenlightenment. An age of missing information.

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.