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.. . . .. I’m going to talk today about energy and climate. And that might seem a bit surprising because my fulltime work at the foundation is mostly about vaccines and seeds,about the things that we need to invent and deliver to help the poorest two billion live better lives. But energy and climate are extremely important to these people,in fact,more important than anyone else on the planet. The climate getting worse means that many years that many years,their crops won’t grow . There will be too much rain,not enough rain,things will change in ways that their fragile environment simply can’t support. And that leads to starvation,it leads to uncertainty,it leads to unrest. So, the price of energy is very important to them. In fact, if you could pick just one thing to lower th e price of, to reduce poverty, by far you would pick energy. Now ,the price of energy has bee down over time. Really advanced civilization is based on advances in energy.The coal revolution fueled the Industrial Revolution, and,even in 1990s we’ve seen a very rapid decline in the price of electricity, and that’s why we have refrigerators,airconditioning, we can make modern materials and do so many things. And so ,we’re in a wonderful situation with electricity in the rich world. But, as we make it cheaperand let’s go for making it twice as cheapwe need to meet a new constrain,and that constrain has to do with CO2. CO2 is warning the planet, and the equation on CO2 is actually a very straightforward one. If you sum up the CO2 that gets emitted,that leads to a temperature increase, and that temperature increase leads to some very negative effects: the effects on the weather, perhaps worse, the indirect effects,in that the nature ecosystems can’t adjust to these rapid changes, and so you get ecosystem collapses.Now, the exact amount of how you map from a certain increase of CO2 to what temperature will be and where the positive feedback are, there’s some uncertainty there,but not very much. And there’s certainly uncertainty about how bad those effects will be, but they will be extremely bad. I asked the top scientists on this several we really have to get down to near zero? Can’t we just cut it in half or a quarter? And the answer is that until we get near to zero,the temperature will continue to rise. And so that’s a big challenge. It’s very different than saying “We’re a twelvefoothigh truck trying to get under a tenfoot bridge, and we can just sort of squeeze under.” This is something that has to get to zero. Now,we put out of a lot of carbon dioxide every year, over 26 billion tons. For each American, it’s about 20 tons。 for people in poor countries,it’s less than one ton. It’s an average of about five tons for everyone on the planet.And, somehow, we have to make changes that will bring that down to zero. It’s been constantly going up. It’s only various economic changes that have been flattened it at all, so we have to go from rapid rising to falling, and falling all the way to zero. This equation has four factors, a little bit of multiplication: So, you’re got a thing on the left,CO2,that you want to get to zero,and that’s