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

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

By fundamentally changing how we design the places and systems that enable our daily lives, we can slash emissions way beyond the immediate carbon savings - because our own personal emissions are just the tip of a vast iceberg of energy and resources consumed far from our view.

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.

Clean air and water, a diversity of animal and plant species, soil and mineral resources, and predictable weather are annuities that will pay dividends for as long as the human race survives – and may even extend our stay on Earth.

We get so little news about the developing world that we often forget that there are literally millions of people out there struggling to change things to be fairer, freer, more democratic, less corrupt.