Copenhagen has done a remarkable job creating streets that are focused on bicycles and pedestrians.

I think there's a gigantic generation gap in terms of how people understand the Internet and how much they think technology is an important factor in social change.

You don't change the world by hiding in the woods, wearing a hair shirt, or buying indulgences in the form of 'Save the Earth' bumper stickers. You do it by articulating a vision for the future and pursuing it with all the ingenuity humanity can muster.

Urban retrofitting: creating different sorts of spaces and uses out of places that are already there.

We have to craft new political realities, not only in places like India, Afghanistan, Kenya, Pakistan, but here at home as well. Another world is possible.

If mass media, social isolation in the suburbs, alienating workplaces and long car commutes create a bunker mentality, the Internet does the opposite.

By looking at climate change as a clean energy generation problem, we're setting ourselves up not to solve it.