I have felt for a long time that the pathway to solving the climate crisis is through the building of a massive grassroots army of men and women who will go out there and win the conversation on climate, and persuade businesses, and universities, and towns to switch to renewable energy and to reduce emissions. And the big change from ten years ago is that people are way more receptive, not only to the message that we have to act, not only to the message that now we can act, we have the solutions now - that's the biggest change - but also willing to make a commitment that we will act.

The climate crisis requires a bottom-up, grassroots demand for solutions because the elites in many parts of the world are under the influence of old industry.

It is just human nature to take time to connect the dots, I know that. But I also know that there can be a day of reckoning when you wish you had connected the dots more quickly.

There's lots about politics I don't feel comfortable with. To talk about the politics of future ideas is impossible in soundbite form.

There is an air of unreality in debating these arcane points when the world is changing in such dramatic ways right in front of our eyes because of global warming.

I don't have the illusion that there's any position or role in the world with as much potential for bringing about change as that of president of the United States.

What changed in the United States with Hurricane Katrina was a feeling that we have entered a period of consequences.