American democracy is in grave danger from the changes in the environment in which ideas either live and spread or wither and die.

The insistence on complete certainty about the full details of global warming-the most serious threat we have ever faced-is actually an effort to avoid facing the awful, uncomfortable truth: that we must act boldly, decisively, comprehensively, and quickly, even before we know every last detail about the crisis. Those who continue to argue that the appropriate response is merely additional research are simply seeking to camouflage timidity or protect their vested interest in the status quo.

The heart of the security agenda is protecting lives, and we now know that the number of people who will die of AIDS in the first decade of the 21st Century will rival the number that died in all the wars in all the decades of the 20th century.

I take no pleasure in the fact that the scientific predictions I’ve relayed to popular audiences turn out to be true.

The cost reductions for renewable energy continue downward in a very dramatic way. We're in the early stages of a sustainability revolution in the globe that has the scale of the industrial revolution but the speed of the digital revolution. And you see it with renewable energy and you see it with LED lighting, which takes a fraction of the energy for the existing bulbs. All new lights are going to be LED. Electric vehicles. There are a lot of changes underway right now. I'm excited by the prospect, and I look forward to working in the months and years to come to accelerate this transition.

Mother Nature does not do bailouts.

Political will is a renewable resource, and everyone can have it in abundance if they so choose.