This is where I part company with many environmentalists. With 6.5 billion people going to 9 billion, much of the environment is unsavable. But if we warm significantly more than 2°C from pre-industrial levels -- and especially if we warm more than 3°C, as would be all but inevitable if we keep on our current emissions path for another decade or so -- then the environment and climate that made modern human civilization possible will be ruined, probably for hundreds of years. And that means misery for many if not most of the next 10 to 20 billion people to walk the planet.

Joseph Romm