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

Cabbies in particular seem to like discussing the fate the Earth.

There is no such thing as garbage, just useful stuff in the wrong place.

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

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.

I think we're going to start to see a new model of civic advocacy where people get together once in a while to protest, but it's more about an ongoing, sustained engagement in issues, networks and communities about which people care.

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