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.

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.

For carbon-neutral cities, there are things worth talking about in how our consumption patterns can change - sharing goods, etc. - but those are a fraction of the impacts of transportation and building energy use. If we need to choose priority actions, the most important things are to densify, provide transit, and green the buildings.

There are a lot of different ways of building a prosperous society, and some of them use much less energy than others. And it is possible and more practical to talk about rebuilding systems to use much less energy than it is to think about trying to meet greater demands of energy through clean energy alone.

Remember, our focus should remain on development because it is development alone that can transform this nation as well as the lives of its people.

A lot of my nonfiction is very strong environmental stories - I was the first guy to write about the dolphin killings in Japan.

By the time we see that climate change is really bad, your ability to fix it is extremely limited... The carbon gets up there, but the heating effect is delayed. And then the effect of that heat on the species and ecosystem is delayed. That means that even when you turn virtuous, things are actually going to get worse for quite a while.

I'm extremely positive about investment in Africa. Africa has a wonderful climate, wonderful people, and amazing possibilities. Africa has been called dark and hopeless, but today it is neither of these. Africa is awakening. It's a huge market of almost a billion people with huge resources and a young population. It's the best place to invest.