 Thanks, Chuck. So I'm going to put on my scientific assessment panel hat for this talk. And I'm going to do so because I think there's actually a little bit of a debt of gratitude that needs to be extended to the Nimbus community and the NASA community in general. And NOAA, too. I don't want to exclude NOAA. And I'll get to that point at the end. I think I'll make a very, not quite a scientific point, but a point that I think is quite fair at the end. First, I'm going to give you a short history. Many of you know Nimbus-4 was launched in 1970 with the BUV instrument. I'm going to talk about the ozone instruments in particular because I'm going to keep coming back to the scientific assessment and the Montreal Protocol. And so BUV was one of the fundamental ozone measurement instruments in the early years. Now, there were other instruments measuring temperatures in the stratosphere. Bill's already talked about that a little bit. There were instruments on Nimbus-7 like limbs. Jack talked about the limbs instrument. I'm going to focus on ozone in particular. So the profound, the really interesting thing is in 1974, Mario Molina and Sherry Rowland published a paper in which the identified chlorofluorocarbons as ozone-depleting substances. We all remember CFCs, CFCs, chlorine, fluorine, and carbon. CFCs are very stable molecules. They were wonderful molecules as refrigerants, as solvents. They had just a propellants and hairspray. I think a lot of us still remember that. I think almost all of us maybe. And so this was a very, very powerful study that came out. And when it first came out, it was attacked quite a bit. There was a lot of contentiousness from industry, from people who were skeptical about whether CFCs could actually do something to this stratospheric ozone layer. Of course, we all understand that stratospheric ozone, ozone screens, ultraviolet radiation. So in 1978, NIMBA 7 was launched. There had been a lot of information accumulated about ozone depletion by that time. In 1981, negotiations began on an agreement to actually protect the ozone layer. So that was very early on. And there are a few people in this audience who are actually working on the assessments that we're looking at the impact. And I've kind of blown past it really quickly, but the supersonic transports and the shuttle put in chlorine and NOx into the atmosphere. But in particular, CFCs, again, attacking the ozone layer. So in 1985, there was a real fundamental change in how we looked at the ozone layer. And this was the publication of a study by Joe Farman, Brian Gardner, and John Shanklin that showed that there was very severe ozone loss over Antarctica. This really had a tremendous impact on the stratospheric community because nobody understood why ozone should be just on a downward trajectory toward zero. There were a number of theories that came out. I was a proponent of one theory in particular that unfortunately turned out to be wrong. I actually thought it was a dynamical cause. It was a lifting circulation in the lower stratosphere that could be depressing ozone. And in 1987, there was a field campaign launched to actually go look at, it was the NASA ER-2 and the NASA DC-8 went down to Antarctica to look at these processes. And in one graph, it was a graph produced by the Harvard group, showed very high levels of chlorine monoxide, levels that were well above what you would project if just standard chemistry was going on. So in one graph, they pretty much proved that one ozone was going down and two, it was due to chlorine. And so fundamentally, they demonstrated that this trend here, Farman and Garner and Shanklin actually proposed that it was CFCs, but they didn't have actually their theory of it was incorrect. But the new ideas came along and in fact it turned out that this was due to chlorofluorocarbons. Now just to give you some added information here, there's red points come from Nimbus 7, you can see here, and here's three blue kind of purplish points, this come from Nimbus 4. So you can see, and these are actually the lowest values found in the October average. The black points are the October averages over Hally. The red points and the purple points are the low values that are seen over Antarctica from the satellite image. Now, this trend in and of itself is very interesting to scientists, but what really had a tremendous impact was this first picture. And many of you wonder, why is it called the ozone hole? Well, you know, you try to trace out where the word actually comes from. It's very hard to trace where why it's called the ozone hole. Nobody seems to know, but I'm pretty sure that at the time, it appeared right after this figure was published, and I think it comes about because that's what Sherry Rowland from Molina in Rowland, that's what he called it. He said there's a hole that's formed in the ozone layer. So here's these very, very low values. Here's the, it's a false color image of ozone. And here you can see Antarctica. There's South America, Australia. Here's Africa. And here's this very, very low amount. Now this is PK Bartia down here. PK was the one. He had a huge room. Alf Lag is sitting back here. Alf can probably tell you how big the room was. It contained all the computers that actually helped to produce this particular figure. But this figure had just an incredible impact on the community at that time. The other thing was, and I haven't mentioned this, is a lot of people have said that NASA was this Nimbus data was being thrown out. In fact, it wasn't being thrown out. It was being flagged. And it was flagged because it was well below, these red points were well below the climatology that you expected over Antarctica. And so naturally, what's a natural scientific inclination? You start to get funny values. And your first impression is, oh my God, what have I done wrong? Why is our instrument failing? In this particular case, they were looking into this. PK was. And actually came to the conclusion that, in fact, the instrument was working fine. And he actually put in, in late 1984, the early 1985, he put in a submitted a paper to the IAGA meeting in Prague that was in August of 1985 that was going to show these extremely low values over Antarctica. But the British Antarctic Survey publication appeared a couple months before that. And actually, the BIS guys had been looking at the problem for about a year. So we have the, there's the urban legend that NASA was throwing data into the bit bucket. It's absolutely an urban legend. And actually the story, the real story is actually better. That the Nimbus people, PK and others, were looking at the data carefully before they rushed out and put something into press. So don't believe the urban legend. The true story is actually a better scientific story. Okay. So these particular, this particular image that you see over here appeared in this three volume set, Atmospheric Ozone 1985. This is a pretty good size book. It's about, I don't know, three, four inches thick, three volumes. This book with these images in it, this was the science that formed the basis for the 1987 Montreal Protocol. A lot of people say, the ozone hole, that's what led to the Montreal Protocol. Well, all the negotiators had that in the backs of their heads. But they're actually looking at this volume, this huge scientific assessment. The work of hundreds of scientists from around the world. In fact, there's another one that's coming out. It'll be appearing in January 1st of 2015. And there's a number of people here at Goddard who are still working on these assessments. So now, this is where we are now with the ozone hole. You see, it actually was plunging. And in the 1990s, it kind of hit bottom. And, you know, if you kind of look at it here, maybe with a little bit of a filter in your eyes, it maybe looks like there's some hints that things are getting better. Here's what the picture looked like in 1979 of the ozone hole. That's an October average. And this is the average from last October. Now, we're in the middle of the ozone hole season right now. These are actually a series of pictures. Here's one of the old BUV pictures. You didn't get any backscattered sunlight, so that's a data void right there. But you can see these low values and how it got worse. And now, there's maybe a hint that it's not as bad as it was in, say, 2001. So there's some hints now that things are getting better. But here we are in September 2014. And there's still a very, very big ozone hole over Antarctica. Okay? And why is that? That's because chlorofluorocarbons, these gases, the CFCs, have very long lifetimes. Lifetime of CFC 11 is about 55 years. The lifetime of CFC 12 is about 102 years. Okay? Now, can you start that? I'm going to show you a little movie here of what would have happened. This is actually the model that Jack K. worked on back in the day. This is the evolution of that to a modern model. On this top left picture, it shows the levels of chlorine and bromine in the stratosphere. So you can think about this. This is the level of chlorine and bromine available for destroying ozone. Here, you can see a little red point. You can follow this trajectory. And in the other model simulation, it keeps going up and up and up. I call that the world avoided here. And you can see very, very low values over there. It's going through each month. This is global total ozone. So just average over the entire thing. You can see that ozone is going down as chlorine goes up with this black point there and that black point there. And you can actually see the difference between the ozone simulation here, which is this, and the ozone simulation here, which is that. And if actually you look up here, this is now at 2030, you can see there's every year an Arctic ozone hole forms. And so as you go through here, you can see as chlorine continues to climb up from the model simulation here, ozone continues to go down. And the global amount goes down and down and down. The normal amount for global is about 300. And you can just see the values as chlorine continues to go up, how ozone continues to plunge downward. Now this is a modern model. This model has the chemistry impacts the radiation. There are greenhouse gases that are going up in this model. The radiation changes temperatures. Temperatures change the wind patterns. Wind patterns blow things around differently. This is a complete interactive modern model. So you can see by the year 2065, globally we're now less than 100 dobs units. So about two-thirds of the ozone layer is gone by the end of the simulation here. And this is because of the Montreal Protocol. The ozone depleting substances went up and they're slowly falling off because CFCs are very long-lived gases. If nothing had been done, there had been no Montreal Protocol and things had been going up and up and up. By the end of the simulation, ozone's virtually gone. And of course, UV levels. You can take this ozone, you can compute UV. UV indexes have tripled around the world. So typically in the Washington, D.C. area, we get a UV index of something like 12 during July. A fairly high UV index. And here it would be something like 36 or so, 3640. So you would have huge UV levels. Now one thing I will mention about this. So UV levels, you're going to get a fast sunburn. But there are other things that happen. For example, skin cancers are directly proportional to your cumulative UV exposure. Melanoma is related to acute, the blistering kinds of burns that you get. More importantly in this simulation, what you find though is crop yields plummet. You get huge damages to crop yields. And actually by the year of about 2015, here's 2010, so 2015 is about here. Chlorine has gone up a lot. Ozone has declined. There is considerable crop damage by the year 2015. Considerable crop damage. Now right now in this world we produce enough food to feed the planet. So mainly. If you can imagine something like a 15 to 20% loss of crops. By this year, if we had done nothing for chlorofluorocarbons, you can imagine what would have happened in terms of just feeding the planet. And I'll come back to that in a little while. So now I'm going to go on. Come back to the history here. Negotiations. 1985, I didn't mention this, but the Vienna Convention is the agreement that called for cooperation, research and data exchange. But it didn't impose any obligations. The ozone hole was discovered. The Montreal Protocol was adopted. It established control measures on CFCs. It didn't actually stop the production of CFCs. It just controlled the production of CFCs. But as further science comes along, we had more of these assessments that I've talked about that kept strengthening the regulation in George Bush Sr., President Bush Sr., actually banned the production of CFCs in the United States in the early 1990s. And so now, after 2010, there is no allowed production of CFCs or halons in the world. Every country of the world has now signed on to the Montreal Protocol. It's the only agreement in the world that has 100% compliance. And this includes, name the country, Andorra, the little tiny countries of Europe. They've all signed this. Even the quote, the axis of evil has signed this agreement. So it's a universally agreed upon agreement to regulate chlorofluorocarbons. Now, this is another plot that I'm going to show. This is the SBUV data. And so this is from, it goes back to the BUV instrument. And then there is the SBUV got to 1993 on Nimbus 7. And then this is the continuation on various NOAA satellites. In fact, there's a little melding of some of the satellites. And the black line is the smooth version. This is average 60 south to 60 north. So it doesn't include polar losses. But you can see that ozone was going down through the 90s. This big low here is due to Mount Pinatubo. Turns out volcanoes can actually lead to enhanced ozone destruction. The particles that are formed by the sulfate aerosols in the stratosphere can enhance ozone loss. And it appears that over the last few years, if you kind of look here from this period on, it looks like there may be a slow upward drift. And I'm going to show actually a plot that appeared. I talked about this new assessment that comes out in 2015, or January 1st. But we already released what's called the Assessment for Decision Makers. It's a scientific, the short scientific document that goes to the parties themselves and will be discussed in Paris in about a month. And this actually, you can see this is 1979 to 1997. This is a trend as a function of altitude. This is the northern hemisphere mid-latitude, so straight above us here. You can see from 1979 to 1997, ozone was decreasing in the upper stratosphere. And now, if you look from over this 2000 to 2013 period, you can actually see that ozone is going up. These are uncertainties. This tells you that it's actually different from zero. So we can now, in the upper stratosphere, discern that ozone is increasing. So ozone-depleting substances are on the decline. We measure those all over the place. And now we can see that from an instrument like the BUV-SBUV series, that ozone is in fact starting to increase in the upper stratosphere. Now, one thing I don't mention here of this is due to the decline of OD, of ozone-depleting substances like CFCs. About half of it is due to climate gases, in particular CO2. CO2 cools off the upper stratosphere, and that actually slows down the ozone loss process. So about half of this increase is due to OD, to CFCs, and about half of the increase is due to climate gases. So just a quick summary. The observations from Nimbus IV and Nimbus VII had this tremendous impact, I think, on the Atmospheric Science community. Although the ozone hole wasn't the driver behind, that huge document I'm talking about was the real driver behind the signing of the Montreal Protocol, the ozone hole sat in the back of all of these negotiators' heads. You can talk to them. I go to these meetings twice a year, and you talk to these folks, and even today, those ozone hole pictures still have a dramatic impact on the negotiators and gives them the emphasis to continue to go forward with regulations. And as I already mentioned, ozone-depleting substances, they're declining. We have lots of observations of this, and the ozone layer is beginning to show signs of recovery. And now I'm going to one last thing. It was negotiated in 1987, ratified by the U.S. Senate in 1988, and I just as a point, the Montreal Protocol, this is a famous liberal who said this, the Montreal Protocol is a model of cooperation as a product of the recognition and international consensus that it was a global problem. Both in terms of its causes and effects, it is a monumental achievement. This is one of the famous liberals that have been presidents of our country, Ronald Reagan. Now, I'm going to add one thought here, and this is, I think, in, you know, I was, I did a lot of work on the Nimbus data over the years as a scientist here at Goddard, and for that, I'm actually a proud and grateful. But I want to add a little thought here. I mentioned that if the Montreal Protocol had not been assigned, agreed to, signed by all the nations of the world, we'd be in a real mess right now. There would be tremendous food shortages. The human impact would be rather modest, but the tremendous huge shortages, when, in fact, if you go back to what happened in Tunisia a few years back, they started having riots over the increase of food prices. This is the first thing that would have happened. As food shortages began, food riots and political instability would begin. They don't give out metals for solving problems that didn't appear, okay? So no scientist is going to get a medal for all of this, although Mario Molina and Sharon Rowland did get the Nobel Prize. But for all the people who supported Nimbus, who made these early observations allow us to understand what happened to Ozone and the continued work on that, nobody's going to get credit for having avoided these food riots, the emergence of politicians who would exploit this for their own political purposes and leading to a lot of instability around the world. Nobody's going to get credit for having stopped that stuff. But I think NASA, the Nimbus program and the continuing work on that, the scientists can take a lot of, and the engineers behind it, all the people who designed these satellites and worked on, can take a lot of, I think, quiet pride in the world that was avoided by massive Ozone losses. So with that, I'll close. And thank you to all of you who worked on that. Thank you.