 We need energy. It's absolutely crucial to human well-being, but at the same time the system we have is not going to work into the future. I think the biggest risk is that the energy system that we built that did such a wonderful job taking us through the first and second industrial revolutions, it turns out that energy system is also, in a way, making our lives unsustainable in that the waste products from that energy, the carbon dioxide that we're putting into the atmosphere, and actually other things, particulates, number one are making it so the world is getting warmer. And number two, there are local air pollution issues that particularly in the developing world where they don't have good regulations are a significant risk for the health of local populations. So I focus most of my time on climate change because I think that is the biggest, hardest challenge. So for the last 15 years or so I've worked on technology called carbon dioxide capture and storage and the basic idea is that instead of allowing carbon dioxide to go into the atmosphere that you capture it you scrub it out of the smokestack of a power plant, for example, and you take it and you compress it into a liquid and you pump that deep underground where it can be permanently trapped. Many studies are now showing that it's not going to be enough to simply reduce emissions from existing sources, that in fact we're going to need to start taking carbon dioxide out of the atmosphere if we're going to be able to have emissions reductions that are large enough, quickly enough. And the idea is that we could combine bioenergy with carbon capture and sequestration. So we grow plants, they take carbon dioxide out of the atmosphere. We then convert that into energy and in the process strip off the CO2 so we can actually have negative emissions. One of the questions people have today is well do we really need to mitigate climate change? Maybe we should just adapt. Well all I can say is we haven't seen anything yet that we are at the very very early stages of a world that is going to warm in ways that we can't fully anticipate. So I don't think we have a choice to just say let's adapt. I think we have to mitigate as hard as we can do and we're going to be adapting to. We don't have a choice. That's my view.