The models that have been constructed agree that when, as has been predicted, the level of carbon dioxide or its equivalent in other greenhouse gases doubles from pre-Industrial Revolution concentrations, the global average temperature will increase, and that the increase will be 1.5 to 4.5 degrees Celsius or 3 to 8 degrees Fahrenheit... In Dallas, for instance, a doubled level of carbon dioxide and other gases like methane, would increase the number of days a year with temperatures above 100 degrees from 19 to 78 each year.

There's always the danger that people will simply sign online petitions, the way they used to just mail in checks, and there's the greater possibility we'll just spend our whole lives staring at screens and never get anything done.

A voluntary simplification of life-styles is not beyond our abilities, but it is probably outside our desires.

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."

The consumer culture in general has washed over our civilization. For the last 50 years, if you've had a credit card and some access to money, you don't really need neighbors around you. And as a result, they dwindled. The average American has half as many close friends as they did in 1950. Three quarters of Americans don't know their next-door neighbor. They may know their name, but they have no real relationship with them. That's an utterly new place for human beings to find themselves in - I mean, we're a socially evolved primate.

The idea that China and India will just abandon climate action is not true, because they're doing it for more reasons than we are.

[The Maldives] they've become deeply politically engaged - just for instance, the president taught his whole cabinet to scuba dive so they could hold an underwater cabinet meeting along their dying coral reef and pass a 350 resolution to send to the U.N.