Depending on how quickly you get ocean rise, you have people who live in river deltas [at risk]. Bangladesh is largely a river delta, and the rising sea level means that when storms come in, the human sanitation is backing up, the ability to farm, it's destructive-type situations like you saw in New Orleans with Katrina. You're increasing the frequency of that stuff in low-lying areas fairly dramatically.

Now we've got that [children's death rate] down to about 5 percent, so we've more than cut it in half, and that's because we're getting vaccines out, economic improvement also helps there, but the vaccines are why we've seen an acceleration in getting that down.

We need to look at less obvious paths, things like the wind in the jet stream, which is very high up. The material science of what type of kite string you would need to connect up to that. That's still at the basic research level.

We're at the point now where the challenge isn't how to communicate effectively with e-mail; it's ensuring that you spend your time on the e-mail that matters most.

I think it makes sense to believe in God, but exactly what decision in your life you make differently because of it, I don't know.

Take agriculture, where we haven't done much, or sanitation; saying, "okay, we will be able to make a really huge effort there." It really energized the foundation and half of what we've gotten done in this last decade is because Warren [Buffett] trusted us.

Software is a great combination between artistry and engineering.