The climate has always changed. I'm a geologist, I'm a historian of climate and we drill ice cores, we look at the rocks and we see histories of climates. The dinosaurs lived on a world with no ice at the poles and it was really hot at the tropics, and if you don't care about humans and you don't care about the other things on this planet with us, so, it's gonna change, you know, but if you care about humans, we have built for the world that we have. We grow the right crops, we have the right houses, we have the right transportation and so on for the world we have and if that changes that affects us, and so, it's the concern about humans that really makes us concerned about climate. The change early in the 20th century, it was getting warmer for natural reasons. Coincidentally, the sun got a little brighter and the volcanoes sort of quieted down and weren't blocking the sun as much. Late in the 20th century, the volcanoes, the sun didn't do much and our CO2 starts to turn up the temperature and we see warming, but the change late in the 20th century, it's not much bigger than the early one. Our models explain what happened, what nature did, what humans did. The models actually now have been run long enough that they have started making successful predictions. Runs 10 or 20 years ago have proven to be accurate. When we take those and we run them into the future, they say that the changes will get lots bigger unless we change our behavior. The one degree or so that we humans have done could turn into 2, 3, 5, 10 or more in degrees Fahrenheit if we keep doing what we're doing, and so our understanding is that the climate is changing and now that we're mostly in control, but we haven't done much to it less, yet, but we can. It's getting warmer. Over the last century or so, it's warmed by a degree Celsius, just under 2 degree Fahrenheit, and that is having some affects on other things that we worry about. The tropical circulations are getting a little bigger. The world is getting a little more tropical. The tropical circulation, it rains at the equator and then the sinking air dries and makes the Sahara and the Kalahari and other deserts, and those seem to be expanding a little bit. We're seeing warming at the poles, melting of--a lot of the ice on the planet is getting a little smaller, less snow cover, less Arctic Sea ice, fewer glaciers, smaller glaciers. Not everything, the Antarctic Sea ice hasn't changed much yet but primarily we're seeing a lot of changes. Influences? If you're a rare and endangered species, you're seeing where you want to live change and you may have difficulty migrating. If you're a farmer, you probably have had to change a little bit when you plant and maybe what you plant, and so it's starting to show up as an influence on us. It's not an end of the world sort of thing. The change so far is not all that big, but it could get bigger. There's a lot of things we can do to adapt to climate change. We can be smart about our crops. We can look at the forecasts and realize the changes that are happening will accumulate. We can help poor people. Usually, wealthy people who have bulldozers and air conditioners and what have you can handle this, and poor people are the ones that get screwed, and so we can actually look at helping them. We can also look at ways to head off the climate change, and this is tied to the energy issues. We use a lot of energy. You go to the gas station and fill up your car and it's 100 pounds, and you burn that and make CO2 and you enjoy it. You drive with it. You, you know, we heat, we cool, we cook. If we're sick, you take me to the hospital in an ambulance and you breathe for me, you know. We love the use of the energy. A lot of other people in the world would like that too, and right now, at $100 a barrel, there's a lot of people that can't buy the energy because we're buying it, and eventually, we will need something else. Eventually, the oil will run out, the coal will run out. The oil companies are smart. They know where it is. There's a few discoveries to be made, but we sort of know how much is out there and eventually it runs out. To gain the advantages that we get from energy, to make them available to other people, we're gonna need new forms. Some of that will be conservation. If you get more economy out of a given dollar's worth of gas, that's OK. Some of it will be wind, some of it will be solar, some of it will be nuclear, some of it will be biomass. You know, there's all sorts of things that are out there that can be done. We have to change. We have to move away from oil and coal because they will run out. If we burn all the oil and coal and then we change, we'll have it where our grandchildren's grandchildren are living in a really different world that's harder to live in because we've changed the climate, and they'll have to change anyway. And, so the picture is there's a lot of money to be made, there's a lot of good to be made finding energy alternatives. Right now, at $100 a barrel, we import oil at a cost of $500 billion a year. We're spending $1,700 per person in the U.S. per year to bring in oil, and that cost of oil means that poor people elsewhere in the world can't buy it and can't enjoy the benefits from it we get 'cause they don't have $100 a barrel to throw at the oil, and so, there's this Grand Challenge of how do we get more energy or more value for the energy we use for a whole lot of people while not changing the world in a way that our grandchildren's grandchildren look back and say, "What did you do?"