Cities offer us powerful leverage on our most stubborn, wasteful practices. Long commutes in our cars, big power bills from our energy-hogging buildings, shopping trips to buy stuff that'll spend a few short months in our homes and long centuries in our landfills.

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

Cities are responsible for the vast majority of the creation of the economy. They're also places into which we pour the vast majority of resources, the vast majority of energy and the places where a huge percentage of the decisions about how systems are built and how products designed, etc., happen.

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

The planet's biggest problems have to do with sustainability, environmental decline, global poverty, disease, conflict and so forth. Really, they're all interconnected - it's one big problem, which is that the way we're doing things can't go on.

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.

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