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.

The more technology we introduce into society, the more people will aggregate, will want to be with other people: movies, rock concerts, shopping.

As I've said before, I'm a big fan of social media because it allows players and fans to interactive but it can have its pitfalls.

Like most successful businesses, you and your employees have a vast knowledge base and expertise in your vertical, as well as a lot of great video and text content to prove it. So, why not monetize your expertise and create digital products and membership courses?

Open source is a beautiful way of collaborating; but what's happening on the free Internet is more akin to the 'crowdsourcing' of journalists and other content creators by advertisers who no longer have to pay them - only the search engines that parse their articles.