00:00:00 Welcome to this American Chemical Society Satellite Television

00:00:29 Seminar, the first in our series of conversations with Nobel laureates in chemistry.

00:00:35 This program focuses on the work of two of the 1995 prize winners who discovered the

00:00:40 detrimental effects of CFCs, chlorofluorocarbons, on the Earth's protective ozone layer.

00:00:47 We are pleased to have so many high school and college students, teachers and professors

00:00:52 join us today to meet and talk with the Nobel laureates and other distinguished panelists.

00:00:57 I'm your moderator, Megan Beyer.

00:00:59 Our guests are Mario Molina, who is Martin Professor of Environmental Sciences at the

00:01:04 Massachusetts Institute of Technology, and Sherwood Rowland, who is the Donald Bren Research

00:01:10 Professor of Chemistry at the University of California in Irvine.

00:01:15 Professors Molina and Rowland shared the 1995 Nobel Prize in Chemistry along with Professor

00:01:21 Paul Krutzen of the Max Planck Institute of Chemistry in Germany.

00:01:26 To provide additional perspectives on ozone depletion research, two of their colleagues

00:01:31 have also joined us.

00:01:33 Dr. Susan Solomon, who is the Acting Director of the Atmospheric Chemistry Division of

00:01:38 the National Center for Atmospheric Research in Boulder, Colorado, and also a senior scientist

00:01:44 in the Aeronomy Laboratory of the National Oceanic and Atmospheric Administration.

00:01:50 And Dr. Robert Watson, who is currently the Associate Director for Environment with the

00:01:55 White House Office of Science and Technology Policy here in Washington, D.C.

00:02:00 And here to host the program is the President of the American Chemical Society, Dr. Ronald

00:02:05 Breslow, who is the Samuel Latham Mitchell Professor of Chemistry at Columbia University

00:02:11 in New York City.

00:02:13 This program is the first in a series of conversations with Nobel laureates that we plan to broadcast

00:02:18 each year for students and faculty.

00:02:21 We are using discussions with recent Nobel laureates in chemistry to highlight the importance

00:02:26 and excitement of chemical research because the Nobel Prize has become established as

00:02:32 the highest recognition bestowed on chemical researchers.

00:02:36 The founder of the Nobel Prize, Alfred Nobel, was a Swedish scientist, inventor, and founder

00:02:42 of many international industries in the 19th century.

00:02:45 When he died in 1896, he left his fortune to be used for prizes in physics, chemistry,

00:02:51 physiology or medicine, literature, and peace.

00:02:55 A Nobel Foundation was established to manage the estate, and the first prizes were awarded

00:03:00 in 1901, five years after Nobel's death.

00:03:04 The value of the first prizes was more than $40,000 each.

00:03:08 In 1991, it reached $1 million each.

00:03:12 Often a prize is divided between two or more winners.

00:03:16 All nationalities are eligible for awards.

00:03:18 Nominations of candidates for the prize in chemistry may be made only by individuals

00:03:24 and institutions that are qualified according to the Royal Swedish Academy of Sciences.

00:03:29 No person may apply directly for a prize.

00:03:33 The award in chemistry is made by the Royal Swedish Academy of Sciences on December 10th

00:03:39 in Stockholm at the Concert Hall.

00:03:41 The awards are presented to each winner by King Carl Gustaf of Sweden.

00:03:46 And the winners also make presentations about their work and attend a banquet in their honor.

00:03:51 In many instances, the award winners have already been recognized by their professional

00:03:56 peers with many other honors and awards.

00:03:59 However, the high degree of attention and publicity that result

00:04:02 from the Nobel Award can sometimes affect the careers and research directions of the winners.

00:04:08 We will be most interested to hear from Professors Molina and Rowland about their reactions

00:04:13 to winning, in addition to learning about their scientific work and collaborations

00:04:17 with other scientists, and how their work has led to involvement with international policymaking.

00:04:24 As the world's largest professional society for chemists, the American Chemical Society

00:04:29 fosters the advancement of chemistry, promotes research in chemical science, and provides

00:04:35 many vehicles for communication and education about chemistry.

00:04:39 We hope that today's program will help to increase your understanding about one aspect

00:04:43 of chemistry, raise your awareness of the need for all of us to have a basic literacy

00:04:48 in science to function as good citizens, and encourage you to learn some more.

00:04:54 Dr. Breslow, will you start with an overview?

00:04:57 Yes, thank you very much, Megan.

00:04:59 I'm happy to put this into some kind of context, because I think that not everyone understands

00:05:03 that chemistry is a rather unusual science.

00:05:08 It does not have in common some of the aspects that many other sciences have.

00:05:13 It of course is a natural science.

00:05:15 Chemists do go through the world trying to understand the natural chemistry that exists,

00:05:18 for instance, the chemistry of life, it's a very important subject that chemists are

00:05:22 very actively worrying about.

00:05:24 But in addition to that, it has a second part, which is really quite different.

00:05:28 Chemistry is different from most other sciences in that it also is concerned with the chemistry

00:05:34 that chemists themselves create.

00:05:36 And that chemistry is concerned with making new molecules, and inventing new kinds of

00:05:47 chemical reactions.

00:05:49 That part is very important to modern society, and it's rather different from the sort of

00:05:54 thing that goes on in many other sciences.

00:05:56 For instance, it turns out that if you think of astronomy or geology, these are fields

00:06:00 that are actively involved in trying to understand the natural world, but they don't have the

00:06:06 same tendency that chemists have to expand the world as much.

00:06:10 And that expansion of the world, of course, is related to the whole CFC question that

00:06:14 we're now talking about.

00:06:16 Turns out that more than 95% of all chemicals, known chemicals, have been made by chemists

00:06:22 and are not discovered in nature.

00:06:24 And many of these things are very useful.

00:06:27 For instance, new medicines, chemists are the ones who devise and create new medicines.

00:06:32 It takes as many as 10,000 new molecules created by chemists to end up with one useful medicine

00:06:37 that really comes out after all the testing is done.

00:06:40 So it's a tremendously active and creative field.

00:06:43 And for this reason, we do tend to call it the creative science.

00:06:46 It also is called the useful science because so many of the compounds that are made are

00:06:50 really useful for bringing our society and our civilization to its current high level.

00:06:57 Now chemists are sufficiently active in all this that in 1995, more than one million new

00:07:03 chemicals were made by chemists.

00:07:05 To give you another sense of the magnitude of this activity, this chemical activity,

00:07:12 there's a group of industries called the chemical process industries.

00:07:15 And these chemical process industries would include the chemical companies, of course,

00:07:18 but they also include the pharmaceutical companies in which chemists are making new molecules.

00:07:23 They also include the metals.

00:07:25 People don't always think about this, but there are almost no natural metals.

00:07:28 Gold and platinum are some natural metals.

00:07:30 All the other metals are made from metal ores, that is oxides, not the natural metals themselves,

00:07:35 by doing chemistry on them, by learning how to turn iron ore into iron metal and then

00:07:40 turning it into steel.

00:07:42 There also, of course, is the plastics industry, the rubber industry.

00:07:45 All of these use chemistry in processes that are designed by chemists.

00:07:49 In fact, over 30% of U.S. manufacturing, based on the value added, that is a way to estimate

00:07:56 the size of this thing, more than 30% is this chemical process industry.

00:08:01 It's the largest segment in the U.S. economy and also in many other economies.

00:08:05 Many other economies around the world that use chemistry in this way.

00:08:11 It turns out that, for instance, the products of the chemical process industry are heavily

00:08:15 used, of course, in automobiles and airplanes and material science.

00:08:18 If you look around in an automobile or an airplane, it is essentially impossible to

00:08:22 see anything there that isn't the product of this chemical process industry.

00:08:26 So now we get to the question of the CFCs and why they were invented.

00:08:31 Refrigerators need a gas.

00:08:32 They compress a gas and the heat comes out, and that's the heat that comes out of the

00:08:34 back of the refrigerator or out of the hot part of an air conditioner.

00:08:37 And then when that gas is allowed to expand, that liquid that has been compressed and is

00:08:41 allowed to expand, that does the cooling.

00:08:44 And this has been known for a while, but the early refrigerators used sulfur dioxide or

00:08:48 ammonia.

00:08:49 These are both dangerous chemicals, and leaking refrigerators caused serious deaths.

00:08:54 There was a lot of interest, of course, in finding a harmless material that one might

00:08:57 be able to use for air conditioners, for refrigerators, so that one could make food

00:09:05 preservation better, so that with air conditioning we could open up various tropical areas to

00:09:10 a more comfortable human life.

00:09:13 And so the CFCs were developed for this, and they were really remarkable compounds.

00:09:18 They did not have any toxic character to them.

00:09:21 Here's a picture of one of the simple chlorofluorocarbons.

00:09:25 The center black ball is a carbon atom, and then the three large balls are the three chlorine

00:09:30 atoms, and then there's a fluorine atom attached to it.

00:09:33 So we call this trichlorofluoromethane.

00:09:35 This is one of the simplest CFCs.

00:09:38 This kind of material, what turned out to be so harmless to humans because it's so unreactive,

00:09:43 that it was quickly adopted as the material for refrigeration, and then it got into other

00:09:48 uses.

00:09:49 It was used in manufacturing of foamed plastics.

00:09:52 It even became a component of some food products, even used whipped cream and things of that

00:09:57 sort because it was so harmless.

00:09:59 Yet there was one problem with it, and this was a problem that was not appreciated.

00:10:05 And what Roland and Molina did was to set out to try to find out what are the properties

00:10:09 of CFCs in the atmosphere, because they seemed to be harmless to humans or to other animals,

00:10:14 and so was there any problem that one should worry about?

00:10:16 And they set about to try to study the fundamental chemistry of these materials, and what they

00:10:20 concluded is that these CFCs could cause a problem with the ozone layer, that they

00:10:25 were able to destroy ozone.

00:10:28 This was a new concept, really, in chemistry, a new concept in worrying about the environment.

00:10:33 And so people were not ready to accept this instantly, but in fact it turned out they

00:10:37 were right.

00:10:38 The result is that chemists have now said, okay, we have to replace them with other compounds

00:10:42 that don't have that problem.

00:10:43 One of the strengths of chemistry is that we can do that.

00:10:45 We can invent new compounds and replace the ones that aren't good when we finally realize

00:10:49 what the problems are.

00:10:50 And the lesson from all this is that we have to be very smart.

00:10:53 We have to know enough to be able to think of what the problems could be with materials,

00:10:58 but we also have to be prepared to take advantage of the creativity of chemistry.

00:11:02 And if we find a problem with compound A, we just make compound B. This is what goes

00:11:07 on in the pharmaceutical industry all the time.

00:11:09 We have to learn how to do that in general, and that is what has been happening in this

00:11:12 field.

00:11:13 Chemists discovered the problem.

00:11:14 Chemists are now working to solve the problem.

00:11:16 It's really a nice example of the application of fundamental chemistry to create a picture

00:11:23 that was so important to human life that it's really hard to imagine other things that were

00:11:28 more important than this fundamental work and what it led to.

00:11:31 This is one of the reasons that I think chemists all over the world are delighted with this

00:11:34 Nobel Prize.

00:11:36 It was a wonderful award of very good fundamental work, which at the same time had tremendous

00:11:41 implications for human health.

00:11:43 And so we are, and we in the American Chemical Society and chemists around the world are

00:11:47 delighted that this was recognized by the Nobel Prize and that we could present this

00:11:51 to you today.

00:11:52 Thank you, Dr. Bresley.

00:11:53 You've set us up beautifully.

00:11:54 You've given us a great overview.

00:11:56 And now, with some trepidation, Dr. Molina, I'm going to ask you to explain the chemistry

00:12:02 of your research in lay terms for us.

00:12:05 Sure.

00:12:06 I'll be glad to.

00:12:07 Let me start out by describing some physical properties of the atmosphere that explain

00:12:13 the existence of the different layers.

00:12:16 The lowest layer in the atmosphere is called the troposphere.

00:12:20 And that's where most of the mass of the atmosphere resides, about 90% of it.

00:12:24 And above about 10, 15 kilometers starts the second layer, which we call the stratosphere.

00:12:31 What we're showing here in this illustration is a typical temperature profile.

00:12:36 The temperature drops with altitude in the troposphere, but in the stratosphere it increases.

00:12:41 It gives rise to this so-called inverted temperature profile, which makes the stratosphere very

00:12:46 stable, particularly towards vertical movements.

00:12:51 In the stratosphere, the weather is always very nice.

00:12:53 It doesn't rain.

00:12:54 There are very few clouds.

00:12:55 And the first question we can ask is, why is it that temperature increases in the stratosphere?

00:13:00 And that's because there is a chemical species at those altitudes, ozone, which is extremely

00:13:06 important.

00:13:07 It shields the surface of the earth from ultraviolet radiation coming from the sun.

00:13:11 And in fact, it's high energy ultraviolet radiation that makes ozone to begin with.

00:13:16 What we have here is an oxygen molecule, which is the oxygen that we breathe.

00:13:23 Normal one has two atoms of oxygen in each molecule, and it breaks apart with this radiation,

00:13:28 making free oxygen atoms, which rapidly find the normal oxygen molecule to make this special

00:13:34 form of oxygen, which has three atoms.

00:13:36 And that's what we call ozone.

00:13:38 And it is this molecule that has this very important property of heating the stratosphere

00:13:44 and shielding the earth's surface.

00:13:46 Now ozone is very unstable.

00:13:48 There are only a few parts per million in the stratosphere, where it's most abundant.

00:13:52 So it's destroyed by various chemical processes.

00:13:55 And one interesting mechanism that explains how it's destroyed involves catalysis.

00:14:00 This is a process which involves very small amounts of certain compounds, which we call

00:14:05 free radicals.

00:14:06 They have an odd number of electrons, and it functions like an amplification factor.

00:14:12 Small amounts, parts per billion levels of these catalysts, can affect and in fact control

00:14:18 part per million levels of this very important species that we call ozone.

00:14:23 Now I could explain sort of in a nutshell with this cartoon how this CFC, ozone depletion

00:14:30 theory functions.

00:14:32 The CFCs are sufficiently stable so that when they are released in the lower atmosphere,

00:14:38 nothing happens to them.

00:14:39 The normal cleansing properties that the atmosphere has, such as rain or some chemical reactions,

00:14:45 do not affect the CFCs.

00:14:47 That's why they can actually diffuse to high altitudes above the ozone layer, and their

00:14:52 solar radiation affects them, decomposes them, releasing, for example, chlorine atoms.

00:14:57 And these are in fact the catalysts that can affect ozone, very strikingly.

00:15:02 Ozone itself, it was until relatively recently, in 1985, that it was observed that something

00:15:10 very drastic was happening to it, specifically over Antarctica.

00:15:15 And what we have here is a result of measurements originally carried out by Joseph Farman of

00:15:21 the British Antarctic Survey and his team.

00:15:25 We have a typical ozone profile, which shows the measurement in September, which is when

00:15:32 the spring starts in Antarctica.

00:15:36 It shows us how most of the ozone is indeed in the stratosphere at those altitudes.

00:15:39 But in a matter of a few weeks, ozone began to disappear very dramatically, and that's

00:15:44 just happening in recent years.

00:15:47 There have been a number of very important experiments, expeditions.

00:15:51 For example, what we have here is a result of measurements from an aircraft, one of these

00:15:56 expeditions, a colleague of ours, James Anderson, and his team, measuring the concentration

00:16:04 of this free radical, chlorine monoxide, which is involved in this catalytic ozone destruction.

00:16:09 And it shows, strikingly, how is it that ozone disappearance is correlated with these very

00:16:15 high levels of these catalysts.

00:16:17 So we have a very strong case linking chlorine from industrial sources to ozone depletion

00:16:23 over Antarctica.

00:16:24 So you did not start your research trying to figure out why the ozone was disintegrating.

00:16:31 That was just a surprise to you.

00:16:33 You were trying to find out.

00:16:34 You started with the CFCs.

00:16:36 We just wanted to find out what was the fate of these compounds in the environment.

00:16:40 We were not directly thinking of the ozone layer at the beginning, but we were worried

00:16:45 about the possible consequences of releasing large amounts of compounds that are not natural

00:16:51 to the environment.

00:16:52 Well, here, 20 years later, it's common knowledge that CFCs are bad for the ozone layer.

00:16:56 But what was it like for you two scientists to have done all of this work in your little

00:17:01 laboratory?

00:17:02 Was there a day when you looked at each other and said, this threatens our world?

00:17:09 And what are we going to do about it?

00:17:11 Was it that dramatic at all, Dr. Rowland?

00:17:13 It's close to that.

00:17:15 We realized in the middle of December of 1973 that it was a serious problem.

00:17:22 We'd started out as an interesting scientific question, but at that point, we realized that

00:17:27 it was much more than that, that it was a major environmental problem and that we had

00:17:31 to publish and talk about it.

00:17:34 Was that something either of you were comfortable with doing?

00:17:40 We had no choice.

00:17:42 We made a conscious decision that we realized this was a very important problem and we really

00:17:47 had to convince society to do something about it.

00:17:51 So that's not the normal role that the scientists played, but we really did it in a very conscious

00:17:56 way.

00:17:57 It was 1973.

00:17:58 What did you know would have happened had you not made this discovery, and were you

00:18:02 not to go out and go public?

00:18:05 Well, we were worried that if society would have continued releasing these compounds indefinitely

00:18:13 that we could have had a very, very serious problem.

00:18:19 In fact, the serious problem did develop, but fortunately we were able to.

00:18:23 But ultimately, it would have meant the loss of life as we know it on this planet.

00:18:28 Ozone is very important to all of the biological species on the planet because it shields us

00:18:33 from ultraviolet radiation.

00:18:35 And the ultraviolet radiation, particularly what we call ultraviolet B, that causes damage

00:18:42 to human DNA and to DNA and all the other biological species.

00:18:47 Life as we know it did not develop until the Earth had an ozone shield.

00:18:51 Okay, so we are talking very bottom line kind of issue.

00:18:53 Dr. Rowland, we have a short video clip showing your research labs in the 70s and some of

00:18:57 your present activities.

00:18:59 If you wouldn't mind narrating a little trip through the laboratory for us.

00:19:03 All right.

00:19:07 Back in 1973 and 74, we didn't have much laboratory work that we were doing.

00:19:12 There were no measurements of any of the chlorine-containing compounds in the stratosphere.

00:19:19 We were measuring only in the laboratory some of the properties of the chlorofluorocarbons

00:19:23 and trying to figure out what was going to happen to them from what we knew from laboratory

00:19:28 measurements.

00:19:29 Now as we move into the 80s and the 90s, we have much more elaborate measurements.

00:19:34 And what you're seeing here is a measurement by a gas chromatograph which tells us the

00:19:39 identity and concentrations of molecules in the atmosphere.

00:19:44 And elaborating beyond that, we have now in the last decade been putting our instruments,

00:19:49 our apparatus for collecting materials, on board the NASA DC-8, which you're seeing here.

00:19:55 Now you're walking along in a research aircraft with a whole set of experiments being carried

00:20:00 out by a wide variety of different chemical groups.

00:20:04 And right now, you're now swinging in your seat.

00:20:06 We have a lot of canisters to collect air samples there.

00:20:10 That was Dr. Charles Wong who was on board the aircraft.

00:20:13 Now you're looking at the forward camera out of the DC-8 as we approach a burning agricultural

00:20:18 area in Brazil.

00:20:20 This is now South Africa where they're burning off the fires.

00:20:24 And what you can see is all of the smoke and flame.

00:20:28 And we're interested in understanding what's going on in that kind of biology, that kind

00:20:34 of burning, the biology that comes as you destroy all of that cellulose.

00:20:39 We have in the next slide, I think, if you could call up this, we're going back to what

00:20:45 Mario and I started out with.

00:20:47 You have to ask what happens to individual molecules that are released to the atmosphere.

00:20:52 New chemicals, as you heard from Dr. Breslow, are being invented all the time.

00:20:56 What happens to them?

00:20:57 Well, the three main things that happen to them are just summarized here, that either

00:21:02 the sun causes them to break apart or they are dissolved in rainwater and get rained

00:21:07 out or the oxygen or some of the other oxidating materials in the atmosphere cause them to

00:21:13 break apart.

00:21:15 Nothing of these happens to the chlorofluorocarbons.

00:21:18 They don't break apart in sunlight down at the ground level.

00:21:22 They don't dissolve in rain.

00:21:25 They don't oxidize.

00:21:26 And that means they last for a period of time of 50 to 100 years.

00:21:30 That gives them plenty of time to get into the stratosphere.

00:21:33 So one of the things that my research group has been doing is going around the world collecting

00:21:37 air samples.

00:21:38 The next one we'll show, Patricia Rogers, who was on the island of Nauru, she's carrying

00:21:42 a canister to collect an air sample.

00:21:44 And we've been doing that now since 1978.

00:21:48 In 1987, in the measurements that we made from Alaska down all the way to the South

00:21:56 Pole, and you can see that the amount of the chlorofluorocarbons was present was almost

00:22:01 the same everywhere in the world.

00:22:03 That's because even though it's almost all emitted in the northern hemisphere, what happens

00:22:07 is that it mixes from the north to the south very rapidly.

00:22:11 It is carried up into the stratosphere in the equatorial regions, and then we see the

00:22:16 chemistry that Mario had discussed.

00:22:19 And by following this over a long period of time, this graph here shows that the amount

00:22:24 of chlorine has risen by about a factor of five since 1950.

00:22:31 Back then, most of the material in the atmosphere that contained chlorine was a molecule called

00:22:37 methyl chloride, which is natural.

00:22:39 And all of the rest of it are the chlorofluorocarbons and some related chlorine compounds, methyl

00:22:44 chloroform, carbon tetrachloride.

00:22:46 And it is this process over the last 40 years that brought the question of the chlorofluorocarbons

00:22:54 in the stratosphere to the fore.

00:22:56 Dr. Molina, I think we all, as humans, like to think that our lives make a difference,

00:23:01 and both you and Dr. Rowland certainly have the answer to that question.

00:23:07 How does that make both of you feel?

00:23:09 Well, it is certainly very humbling, but the way I look at it, all this was really the

00:23:17 result of efforts of a scientific community.

00:23:21 We were all working together, and I think the community really did a wonderful job and

00:23:27 was able to come up with a crucial experience at the right time.

00:23:30 Okay, well we're going to let some of our viewers in on this.

00:23:34 We're ready to begin taking your telephone calls.

00:23:37 Please call us at 800-368-5781 or 5782.

00:23:42 And for local callers here in the Washington, D.C. area, it's 202-463-3170.

00:23:48 When you call, a volunteer will answer and will ask you for your site number and location.

00:23:54 Your site number is listed on the label at the top of your site license.

00:23:59 You will be put on hold and will hear the program audio on your telephone.

00:24:04 I'll call you by the name of your location, not by your own name, by the name of your

00:24:08 location.

00:24:09 When you hear your location called, talk right into your telephone handset and tell

00:24:13 us your name, what your question is, who the question is for, and we have several telephone

00:24:19 lines available.

00:24:20 If you should get a busy signal, though, please hang up and try it again.

00:24:24 Remember, you have to give us a valid site number to ask a question.

00:24:28 And while we're waiting for the first call to get connected, we'd like to take a quick

00:24:31 tour of your laboratories at MIT.

00:24:33 Dr. Molina, you can now give us a tour on that videotape that you brought and guide

00:24:38 us through.

00:24:39 Sure, I'd be glad to do that.

00:24:43 What we are doing at MIT is some laboratory experiments.

00:24:47 I want to stress here that atmospheric chemistry is very much of an experimental science.

00:24:52 So we carry out measurements in the laboratory to find out how fast reactions take place

00:24:58 that are important in the atmosphere.

00:25:01 And this information, together with information about how the atmosphere functions, is put

00:25:05 together in models of the atmosphere.

00:25:08 And then other very important experiments need to be carried out, namely to go out and

00:25:13 measure in the atmosphere whether these predictions are indeed true, whether all these compounds

00:25:19 that we predict should be there are indeed there.

00:25:22 So in our laboratories at MIT here, we show some of my students investigating the nature

00:25:28 of some of the reactions that we think are important.

00:25:33 For example, we did not really predict that ozone was going to be depleted very severely

00:25:37 over Antarctica.

00:25:38 At the beginning, we just had a general prediction of effects on ozone from the CFCs.

00:25:43 And one point that we did not consider is that there are clouds over Antarctica.

00:25:48 It's sufficiently cold so that these clouds form.

00:25:52 And so there's a very interesting set of chemical reactions which we simulate in the laboratory,

00:25:57 which involve processes on these cloud particles, which convert chlorine from a form that does

00:26:03 not affect ozone to a very active form, these free radicals that I talked about earlier

00:26:09 that are involved in the catalytic cycles.

00:26:12 So we need to continue learning more and more about all these processes in the atmosphere.

00:26:18 So we are carrying out a variety of experiments to try to better predict, particularly what's

00:26:24 happening in the northern hemisphere, where the chemistry is more subtle than in the southern

00:26:28 hemisphere.

00:26:29 There is, of course, also ozone loss in the north, but it's not quite as localized and

00:26:34 as severe over the south.

00:26:37 So we have here just several of my students.

00:26:41 My wife is also a chemist, and she's collaborating with these measurements.

00:26:45 And we're trying just to better predict how the atmosphere functions in these very general

00:26:52 terms.

00:26:53 We have a caller from Anna Cortez, Washington.

00:26:56 You have a question for one of our panelists?

00:26:57 Yes, this could actually go to either Dr. Molina or Roland.

00:27:03 But there are apparently conservative media that believe that ozone depletion is not a

00:27:10 problem and that CFCs are not harming the stratosphere.

00:27:15 And I wonder if you could tell us whether or not there are scientists who have doubts

00:27:20 about what's taking place.

00:27:22 And also, if you would deal with the supposedly the fact that you've got natural cycling of

00:27:30 ozone levels that took place long before there was any CFCs around.

00:27:34 Dr. Roland, Dr. Molina?

00:27:37 Yes, there are natural cycles.

00:27:39 The amount of ozone over any given location in the United States varies with the season.

00:27:47 There is also a smaller amount that is variation with the amount of sunspots on the sun.

00:27:58 That's an 11-year cycle.

00:28:00 And so both of those are natural cycles.

00:28:04 But in addition to that, there is a long-term trend that has built up over the period of

00:28:10 time that we have been measuring ozone.

00:28:14 The evaluation of the science of ozone spread very quickly after Dr. Molina and I first

00:28:23 published our paper and the first discussions came up.

00:28:27 It became necessary to have an independent evaluation of this.

00:28:33 And a committee was appointed by the National Academy of Sciences to look into the ozone

00:28:39 problem.

00:28:40 And it was reported in 1976 that the chemistry that we were talking about made sense and

00:28:46 was a serious problem.

00:28:48 And the National Academy of Sciences continued to report in 1979, 1982, 1984.

00:28:55 And then it turned to the World Meteorological Organization and NASA.

00:28:59 And Bob Watson, who is here, was very important in all of this.

00:29:04 The evaluations done by international scientific panels.

00:29:08 And those reports came out in 1986 and 89 and 91 and the most recent one in 95.

00:29:15 And all of them substantiate the understanding of the ozone, which we have said is perfectly

00:29:25 straightforward.

00:29:26 And now if you go to the scientific meetings of the American Geophysical Union, you don't

00:29:30 see anybody raising the question of whether ozone depletion is real.

00:29:35 It's only out in the lay public and, as you say, with conservative, some of the conservatives

00:29:41 that don't follow what actually goes on in the scientific community.

00:29:45 Okay.

00:29:46 Well, Dr. Rowland, you certainly had your answer to that question.

00:29:50 We're going to Cuyahoga Heights High School in Cleveland, Ohio now.

00:29:53 You have a question?

00:29:55 Yes.

00:29:56 I'm a student at Cuyahoga Heights and we'd like to know what is the most recent data

00:30:03 about the amount of CFCs in the atmosphere today?

00:30:06 What is the current status of CFCs?

00:30:08 The most recent data, yes.

00:30:11 Well, perhaps I could start with that, but the CFCs have been banned, so they are regulated

00:30:20 now by the end of 1995.

00:30:22 They are no longer being produced in industrialized countries.

00:30:27 But one can actually measure their amount in the atmosphere and, indeed, the amounts

00:30:32 correspond very closely to the industrial production.

00:30:36 But it's clear that in very recent months, one has been able to show a decline in the

00:30:43 rate at which they are being placed in the environment.

00:30:48 So with other words, measurements of the amount of CFCs throughout the atmosphere now are

00:30:54 providing a clear indication that these regulations are having an effect and that the industry

00:31:00 is, in fact, no longer producing them.

00:31:02 But they are going to remain at high levels in the atmosphere for several decades because

00:31:08 the residence time in the environment is, indeed, very long.

00:31:11 And Dr. Rowland has something to add, don't you?

00:31:13 Well, I think if you look at the slide that is supposed to come up now, these are the

00:31:17 measurements that have been made by the National Oceanic and Atmospheric Administration for

00:31:22 the molecule fluorocarbon-11 at a number of sites all over the world.

00:31:27 And their measurements started 15 or 20 years ago.

00:31:30 And as you can see, by looking in the last several years, everything has flattened out.

00:31:35 And the reason it's flattened out is because the Montreal Protocol was established which

00:31:41 calls for regulation of the emissions of chlorofluorocarbons.

00:31:44 And we know from these measurements made in the atmosphere itself that the Montreal Protocol

00:31:50 is taking effect.

00:31:52 But the countries of the world are going ahead and finding replacements and no longer

00:31:58 manufacturing the CFCs.

00:31:59 So in that sense, it's a success story that the amounts in the atmosphere are leveling

00:32:05 off the total amount of chlorine probably reached a maximum last year or this year because

00:32:10 of the controls, especially on methyl chloroform and the CFCs.

00:32:13 Thank you, Dr. Rowland.

00:32:14 And you know, we have a lot of calls coming in.

00:32:16 So we're going to be trying to get through your calls a little bit more quickly.

00:32:22 We have a call now from Marblehead, Massachusetts.

00:32:24 Hello.

00:32:25 I was wondering if the Clean Air Act has had an effect on the ozone.

00:32:31 And if so, has it been significant?

00:32:34 We might also want to talk about some of the global agreements that may have had an impact.

00:32:39 Dr. Rowland or Melina?

00:32:42 Perhaps I should start out by clarifying that we have two ozones, the good ozone and the

00:32:48 bad ozone, as we call it.

00:32:51 Ozone is a product of smog.

00:32:55 If you consider hydrocarbon fragments and nitrogen oxides, which come from combustion,

00:33:01 like in automobile engines, and the sunlight, that makes ozone at low altitudes.

00:33:07 And that ozone is bad for you because you breathe it.

00:33:10 The ozone that the CFCs destroy exists in the stratosphere, but it's very good for us

00:33:15 because it shields ultraviolet radiation.

00:33:18 The Clean Air Act actually has something to do basically with ozone in smog, but I think

00:33:25 indirectly it also is connected with the CFCs.

00:33:29 Perhaps we could let Bob Watson talk more specifically about the details of the Clean Air Act.

00:33:36 Yes, the Clean Air Act indeed is used as a legislative vehicle in the United States to

00:33:42 regulate the use of chlorine and bromine-containing compounds.

00:33:47 So we try and align our U.S. regulatory actions with the international actions under the Vienna

00:33:53 Convention for the Protection of the Ozone Layer and the subsequent protocols that were

00:33:57 negotiated in Montreal, London, Copenhagen, and Vienna.

00:34:01 So as Mario Melina says, the Clean Air Act is very important to reduce tropospheric ozone

00:34:06 and also to reduce the CFCs and the halons and other chlorine and bromine-containing

00:34:11 compounds that destroy stratospheric ozone.

00:34:13 We have another call from Overland Park, Kansas.

00:34:16 You have a question for one of our panelists?

00:34:18 Yes, I was thinking, what do you think the ozone layer will look like in the year 2000?

00:34:24 Where are we headed on the ozone layer?

00:34:27 Because of the Montreal Protocol, the amounts of chlorine in the lower atmosphere are reaching

00:34:34 a maximum this year or next, and as we move into the next decade, we don't expect that

00:34:43 amount to change, won't increase very much over what it is now.

00:34:46 And then, very gradually, over all of the next century, the amount of chlorine that

00:34:52 is in the lower atmosphere, and that controls the amount in the stratosphere, will gradually

00:34:57 recede.

00:34:58 But because the lifetimes of the chlorofluorocarbons are the order of 50 to 100 years, they will

00:35:04 last through, appreciable amounts will last all through the 21st century.

00:35:11 And a call from Atlanta, Georgia.

00:35:12 You have a question for one of our panelists?

00:35:14 Yes.

00:35:15 What's the reason that extreme cold or cold weather accelerates the chain reaction of

00:35:21 the chlorine atoms with the ozone molecule?

00:35:24 This might be a question for Dr. Solomon.

00:35:26 I'm sure any of us could easily answer that question, but I can do it.

00:35:31 Let me just interrupt and say that Susan Solomon led an expedition to Antarctica when she was

00:35:39 30 years old, and was directly concerned with this particular problem.

00:35:43 And she's the ideal person to give the answer for this.

00:35:47 Well, thank you, Sherry, for that generous introduction.

00:35:51 I guess in this context, it's not so much the fact that I went to Antarctica as the

00:35:55 fact that I also was one of the first people to suggest that reactions on the surfaces

00:36:00 of polar stratospheric clouds might be the reason for the Antarctic ozone hole.

00:36:05 And basically, what happens there is that the chlorine from CFCs gets liberated in the

00:36:10 stratosphere, but can also get tied up to some extent in molecules like hydrochloric

00:36:15 acid and chlorine nitrate.

00:36:16 So, to the extent that those molecules can hang onto the chlorine, ozone is protected.

00:36:21 What happens on the surfaces of polar stratospheric clouds that form only at extremely cold temperatures

00:36:27 is that that chlorine gets liberated again.

00:36:30 So, it turns back into the very active form and goes on to destroy ozone much more effectively

00:36:34 than in those parts of the atmosphere where no surfaces exist.

00:36:38 Okay.

00:36:39 You know, we might want to take a step back and find out what led you to, you know, we

00:36:43 know what happened as of 20 years ago.

00:36:45 You were in the lab.

00:36:46 You started looking at CFCs.

00:36:47 What did you do before that?

00:36:49 Give us a little background on, you know, where you were and how you got there.

00:36:56 My training was at the University of Chicago, and I worked for Professor Willard Libby,

00:37:02 who invented what is known as carbon-14 dating.

00:37:07 It's the use of radioactivity in the atmosphere to tell you something about the world, and

00:37:13 in particular, revolutionized archaeology.

00:37:16 My own training then was in using radioactivity, but not in the atmosphere.

00:37:21 And that was the major part of my career for the first 20 years.

00:37:26 And then, in the time period around 1970, I started being interested in something, doing

00:37:34 something a little bit different without leaving behind the other, but expanding it a little bit.

00:37:39 And there's a question, what could we do in the environment?

00:37:44 When you work with radioactivity, you're working with trace substances, very, very small concentrations.

00:37:50 And, of course, that's what the atmosphere is.

00:37:51 It is nitrogen and oxygen and, for the most part, a lot of very trace concentrations of other compounds.

00:37:58 And when I heard about the chlorofluorocarbons, I became interested in it,

00:38:03 proposed to the U.S. Atomic Energy Commission that we could just try to find out what was going to happen

00:38:11 to these compounds that had been made by man.

00:38:14 And then a very bright postdoctoral joined my research group.

00:38:19 We talked about various kinds of research that he might do.

00:38:23 And Mario chose to, let's say, well, let's look into the chlorofluorocarbons.

00:38:27 And what has your background been? What have you been doing?

00:38:31 What I have been doing before that, my PhD, was in a very academic field.

00:38:35 I was investigating chemical lasers.

00:38:38 And essentially, I was interested in that, to understand at the very fundamental level,

00:38:42 how chemical reactions take place, how do they occur, and so on.

00:38:47 But I was quite interested in applying this knowledge

00:38:50 and seeing whether there was something that could more directly impact society.

00:38:54 And one of the very good attributes of atmospheric chemistry is that we have been able,

00:38:59 on the one hand, of course, to do something very applied.

00:39:02 But it's still a very fundamental science.

00:39:04 We're very close to basic science that has repercussions for other branches of chemistry as well.

00:39:09 Okay, we have another call from Bridgeport, Connecticut.

00:39:12 You have a question for one of our panelists?

00:39:15 I was wondering, how have EPA regulations helped to correct the ozone depletion problem so far?

00:39:22 And how much of the real problem is based on Freon number 22, the central air conditioning refrigerator?

00:39:31 Yes, maybe I can start to answer.

00:39:34 Freon 22 is less stable than the CFCs.

00:39:39 It has a hydrogen atom in the molecule.

00:39:41 And consequently, a good fraction of its release to the environment gets destroyed before it gets into the stratosphere.

00:39:49 In fact, some of the replacement compounds for CFCs, which we call HCFCs,

00:39:55 have precisely that property of being less stable, and consequently they carry less chlorine into the stratosphere.

00:40:01 EPA actually played an important role early on in terms of regulations within the United States.

00:40:06 For example, the use of CFCs as propellants for spray cans was banned in 1978.

00:40:11 But in more recent years, it was really an international agreement.

00:40:15 It's a truly global-scale problem, so it required the agreement of all the industrialized nations and most developing nations as well.

00:40:24 So at that stage, of course, it's the United States as a country that participated in these negotiations.

00:40:30 And, oh, Dr. Breslin?

00:40:33 I wonder if I might say something about this, because people don't always recognize how much the chemical industry welcomes reasonable restrictions from the EPA.

00:40:42 Not only on chemicals, but also on manufacturing processes.

00:40:47 Most good chemical companies want to operate in such a way as not to damage the world.

00:40:51 They live in the same world we live in. They're not interested in destroying it.

00:40:54 But if you don't have any sensible regulations,

00:40:57 then some of the people who will cut corners will be able to make compounds more cheaply or sell compounds that could be damaging.

00:41:03 And that really, of course, represents an unfair competition to the people who are operating sensibly.

00:41:08 So it's very important to have sensible regulations based on science that really do, in fact, protect us against unpleasant activities of what we might call renegade producers.

00:41:21 Well, we also have a question from Oakwood, Georgia. You have a question?

00:41:24 Yeah, my name is Adam Reynolds from Gainesville College.

00:41:28 And my question was, since the oceans of the world constantly put off tremendous amounts of chlorine,

00:41:34 how can ozone depletion be attributed to mankind?

00:41:38 And since the oceans will continue to produce chlorine, how is eliminating man-made CFCs going to stop the ozone depletion?

00:41:49 Dr. Rowland?

00:41:51 When I first discussed earlier in the program the things which happen to most molecules that are put into the atmosphere,

00:41:58 I talked about the question of molecules that can dissolve in rain water.

00:42:06 And obviously, the things which are in the ocean are soluble in water.

00:42:11 So the ocean has a lot of sodium chloride in it.

00:42:14 And the spray will throw sodium chloride up into the atmosphere.

00:42:17 And that gets washed out by the rain.

00:42:20 And that's true for all of the polar molecules.

00:42:24 The molecules that are soluble in water, they get carried out long before they ever get into the stratosphere.

00:42:30 And you even have a graphic of it.

00:42:32 It's on the middle of this graphic.

00:42:34 It shows for hydrogen chloride, and that would also be for sodium chloride as well, which is in the ocean.

00:42:41 And we have now measurements coming from the stratosphere which show that the total amounts of such inorganic chlorine,

00:42:50 such as hydrogen chloride or sodium chloride, are very small compared to the total amount of chlorine that's carried up there in the organic forms.

00:42:58 The first of those measurements came from the space shuttle back in 1985.

00:43:02 The U.R. satellite has given some very good results in the 1990s.

00:43:08 It's quite clear that almost all of the chlorine that's in the stratosphere is carried up there in the form of being bonded to carbon as CFCs,

00:43:16 man-made molecules, plus methyl chloride, which is the one natural component.

00:43:22 We have another caller, but I'd like to remind everybody, when you do call in, turn the sound down on your set because you'll get feedback if you don't.

00:43:30 And our next caller is from Cheyenne, Wyoming.

00:43:33 Do you have a question?

00:43:34 Yes, I do.

00:43:35 Thank you.

00:43:36 This question is actually in two parts.

00:43:38 The first diagram that you showed in your presentation shows oxygen absorbing UV radiation.

00:43:44 What is the difference in absorption between oxygen and ozone, particularly in regards to UVB?

00:43:51 And the second part of my question is, if UVB flux at the Earth's surface is the main threat to the ecosystem,

00:43:57 are we measuring UVB flux at the surface, and what do these measurements tell us about the change in flux with time?

00:44:04 UVB meaning the ultraviolet rays.

00:44:06 Ultraviolet B.

00:44:08 What I can do is let me take the first part, and then I'll let Sherry continue.

00:44:14 Oxygen molecules indeed absorb ultraviolet radiation, but of short wavelengths, wavelengths around 200 nanometers.

00:44:20 That's a type of radiation that does not penetrate even to the lower stratosphere.

00:44:26 But ozone has a very important property of absorbing longer wavelengths.

00:44:31 Between about 200 and 300 nanometers, it absorbs extremely efficiently.

00:44:37 So even though there's a lot less ozone than oxygen, it's really what absorbs all that extremely efficiently.

00:44:43 So we have two different types of radiation.

00:44:46 And, of course, it's UVB, wavelengths a little longer than 300 nanometers, the ones that can penetrate to the Earth's surface.

00:44:52 Dr. Rowland?

00:44:54 The measurement of UVB can be done in two ways.

00:45:02 One is to do it in an absolute way of actually measuring the amount at each wavelength.

00:45:08 But the standard measurement for ozone that was invented back in the 1920s compares the amount of UVB.

00:45:16 All right, this is the Dobson spectrometer.

00:45:19 If you look at that, it shows an instrument at the surface of the Earth on the lower right looking at the sun and measuring two wavelengths,

00:45:28 one of which is in UVA, which is not absorbed very strongly by the ozone, and one is in UVB, which is absorbed, but not completely.

00:45:37 And you measure the ratio of UVB to UVA.

00:45:40 And that's the standard measurement of ozone is, in fact, a measurement that you have changed the quality of the UV radiation.

00:45:48 If you say there's more UVB radiation, what you say is there's less ozone, because the relationship between UVB and ozone is that tight.

00:45:57 Now, in very recent years, really meaning late 1980s on, we have had direct UVB measurements in Antarctica, in southern Argentina, and in San Diego, California.

00:46:10 Well, that was a very good question, and I hope the guy's doing a paper on it, and he's got it from the horse's mouth.

00:46:15 Central Point, Oregon, can we take your call?

00:46:18 Hello. Yes.

00:46:20 I was wondering, did not Nikola Tesla prove that ozone is repulsed by magnetic fields, such as the north and south poles of a magnet,

00:46:28 which would explain the hole in the ozone over Antarctica, and also shore up theories that ozone runs through natural cycles in the atmospheric concentrations,

00:46:39 causing very hot peaks in temperature in warm, wet periods and ice ages, all dealing with how it absorbs radiation?

00:46:47 Either doctor, what else?

00:46:50 The quick answer is no.

00:46:53 Okay. Dr. Molina.

00:46:55 Yeah, I would say ozone is essentially not affected at all by magnetic fields, and we can show that very strikingly in the laboratory.

00:47:02 So I think the laboratory experiments coupled with atmospheric measurements really show very strikingly that that's not the case at all.

00:47:11 Okay. Stone Mountain, Georgia, we've got a question for one of our panelists.

00:47:15 Yes, I do. My name is David Gibson.

00:47:17 I would like to know, is it possible to make ozone to replace the lost ozone?

00:47:23 Can we patch it up?

00:47:25 Let me just start out by mentioning that the amount of energy that ozone absorbs from the sun shielding it from the Earth's surface is much larger than the amount of energy that mankind uses.

00:47:37 So it's a very large natural system.

00:47:39 It's really not easy to think of ways to replace that ozone.

00:47:43 There are some conceivable ways of adding some other chemicals to the stratosphere that would perhaps compensate for these catalytic effects.

00:47:51 But it's sufficiently complicated that the most likely effect is to actually damage some part of the atmosphere.

00:47:57 So the short answer is no, we cannot yet engineer the entire global system.

00:48:02 Would it be worth any research into that?

00:48:04 I'll just expand it briefly if I can.

00:48:07 Mario explained earlier about the catalytic effect of chlorine.

00:48:12 What the catalytic effect means is that one chlorine atom can cause many thousands of ozone molecules to decompose.

00:48:19 You can do that because it is downhill in energy.

00:48:22 And you don't need energy to make the reaction go.

00:48:25 But to create ozone is uphill, and you have to put in a lot of energy.

00:48:30 It's back to this reaction scheme here.

00:48:33 Making ozone costs you energy, and the only energy source that we have that makes ozone now is the fact that you have the sun shining on the atmosphere.

00:48:45 And as Mario said, that's a very powerful chemical engineering system, and it's not possible for us to intervene on that scale.

00:48:52 We want to take one more call.

00:48:53 That's from Chapel Hill, North Carolina, before we break.

00:48:57 Hi, yes.

00:48:58 This is for Dr. Rowland.

00:48:59 My name is Alan Potts.

00:49:01 I'd just like to have you talk a little bit or explain about your role in influencing more scientific work in the area of atmospheric chemistry

00:49:11 and, furthermore, about your role in bringing faculty together at the University of California, Irvine to work on these problems.

00:49:18 I think I'll pass that second question, Alan.

00:49:22 But I think the whole business of atmospheric chemistry is an interesting area, and it's still very early.

00:49:33 Susan had called at one point that we were in the golden era of this, because it's the combination of instrumentation and interest that has allowed us now to get answers to questions that were raised a thousand years ago and two thousand years ago.

00:49:51 So it's a very exciting time, because the ability of science to get information now on a quantitative basis has led to a lot of interest here, all of the things we're talking about, but also a whole set of problems having to do with the fact that we can now understand the chemistry of individual molecules.

00:50:13 Well, we have so many calls that are still coming in, and I hate to tell you it's time to conclude the question period, but please, we will be continuing.

00:50:22 We will take your calls, so come back with us.

00:50:24 Hold your unanswered questions for the question periods in the second part of our program.

00:50:28 We want to take a moment to thank the local site coordinators at each of the participating locations.

00:50:33 These programs would not succeed without you.

00:50:36 Whether you are at a university, college, school, or company, or with an ACS local section or student affiliate group, we know that you have gone out of your way to make today's program a success for your group.

00:50:47 Please join me in applauding your local site coordinator for arranging your group to receive this program.

00:50:53 During the stretch break coming up, we'll show you two short video news releases pertaining to ozone depletion research and chemicals.

00:51:00 The first was provided by NASA about research on the ozone hole over Antarctica.

00:51:05 The second by the American Chemical Society Inside Science Program on the search for replacements of halons for fire-suppressing gases.

00:51:14 These two pieces give added perspective to the work that we're discussing today, so please take a look at them while you relax during the break.

00:51:22 We'll be back for more discussions with our distinguished panelists in a few minutes.

00:51:26 Ozone is an invisible upper atmospheric gas that protects all forms of life on Earth from most of the sun's damaging radiation.

00:51:55 Radiation that can cause skin cancer, eye damage, and suppression of the immune system.

00:52:01 The harvesting of fish and plant life are also affected.

00:52:05 A vast amount of aquatic life has its beginnings in the oceans near Antarctica.

00:52:11 False color imagery of the South Pole from NASA's Nimbus-7 satellite provides scientists with a road map of daily changes in the ozone.

00:52:22 By tracking this imagery for the past nine years, they have discovered a trend.

00:52:26 Each spring over Antarctica, a hole in the ozone develops, and it has been getting larger year by year.

00:52:34 To date, as much as 50 to 60 percent of the ozone in this area has been lost.

00:52:40 These discoveries prompted a coordinated series of Antarctic ozone experiments.

00:52:45 Last fall, an international effort, including some 150 scientists and engineers from NASA, National Oceanic and Atmospheric Administration,

00:52:55 National Science Foundation, and industry worked together for four months to study this alarming environmental issue.

00:53:03 Scientists used ground-based instruments and launched balloon-borne payloads to sample air chemistry at McMurdo Station in Antarctica.

00:53:12 At the same time, NASA's DC-8 flying laboratory studied the lower atmosphere, making long missions from Punta Arenas, Chile, into the area of ozone depletion.

00:53:23 NASA's high-flying ER-2 plane, carrying a single pilot and a handful of sampling instruments,

00:53:30 flew directly into a layer of atmosphere where the ozone was depleted.

00:53:35 A number of activities contributing to ozone loss have been pinpointed by the scientific and policy community.

00:53:42 No longer do canned aerosol products contain chlorofluorocarbons, or CFCs,

00:53:48 but these harmful gases still get into the atmosphere because they are used as refrigerants, fire retardants, foam-blowing agents, and solvents.

00:53:57 As long as this persists, ozone will continue to be lost.

00:54:01 Initial findings from the summer's ozone expedition verified that there is a complex interplay between CFCs,

00:54:08 chlorine-containing gases, and the meteorology in certain parts of the world.

00:54:13 Ice crystals in the upper atmosphere convert the gases into a byproduct that destroys ozone.

00:54:20 These ice crystals usually only form in the atmosphere of the South Pole because it gets so cold.

00:54:26 This may explain why other parts of the world aren't dramatically affected by the depletion.

00:54:31 Scientists still do not understand all the mechanisms of change,

00:54:35 but thanks to the work of so many, we will soon have a more complete understanding of ozone loss and its threat to the world environment.

00:54:43 In the early 1990s, a new generation of atmospheric satellites will probe even further into the problem.

00:54:56 While U.S. troops are putting out the fires of armed conflict all over the world,

00:55:00 scientists back home are studying new ways to extinguish the genuine fires of combat.

00:55:05 The reason? Pressure to replace the ozone-destroying chemical halon, the world's best firefighting agent.

00:55:12 The same thing that makes it so effective in chemically attacking a fire also is what makes it chemically attack the ozone layer.

00:55:19 Although halon remains perfectly legal to use, it is no longer legal to manufacture,

00:55:24 which is why the Department of Defense initiated an aggressive campaign to find a replacement for all future military and commercial aircraft.

00:55:32 That effort involved all the armed services and the FAA, who together chose two new chemical compounds,

00:55:38 an environmentally benign fluorocarbon that's not nearly as efficient as halon, and CF3I, a chemical with a split personality.

00:55:47 There's no question on a performance basis, there's nothing out there right now in terms of a conventional chemical that's anywhere close to CF3I.

00:55:54 CF3I is the closest to a drop-in replacement that we've had. We published in 78 about how good it is.

00:56:01 It's very close to CF3VR, Halon 1301. The problem is, it is significantly more toxic.

00:56:08 Which means CF3I cannot be used near people.

00:56:12 Leaving the Navy with ships full of sailors, and the Army with tanks and personnel carriers packed with soldiers, searching for other halon alternatives.

00:56:21 Although research has not yet found the answer in solving all of our halon problems,

00:56:27 with all this work going on, with all these good people doing the work, we're really confident that we'll find a solution in the near future.

00:56:35 Until then, these two chemicals, when it comes to aircraft, will have to do.

00:56:41 This is Randy Atkins reporting.

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00:59:57 Welcome back to the second part of the ACS Satellite TV Seminar on CFC's and the ozone layer disrupting a delicate balance.

01:00:05 During the first hour we learned a little about the work

01:00:08 that led to the award of the 1995 Nobel Prize in Chemistry to Professors Mario Molina and Sherwood Rowland.

01:00:15 We also talked about their backgrounds and what led them into scientific careers.

01:00:19 During this hour we are going to delve into the varied research related to Rowland's and Molina's conclusion

01:00:25 that CFC's cause ozone depletion in the stratosphere and the political actions that have resulted.

01:00:31 In part one of this program you reviewed some of the chemical reactions of CFC's with ozone.

01:00:37 We know that you worked together from the inception of the ozone depletion research

01:00:42 and can you describe now how it got started and review some of the events that followed during the 20 years or so

01:00:49 since you were in that laboratory making these incredible conclusions.

01:00:52 I think the place to start actually, I have a slide that will show the starting point for all of this.

01:00:59 It began with an English scientist named Jim Lovelock who invented a very sensitive detector,

01:01:05 electron capture detector, which turns out could be used to measure things in the atmosphere

01:01:12 and one of the things that could be measured was trichlorofluoromethane, one of the CFC's.

01:01:17 He proceeded, first he put it at his home in Ireland and then later on he put it on board a ship that was headed for Antarctica.

01:01:26 The green dots on this show the results that he got from that trip to Antarctica,

01:01:33 that every air sample that he put into his apparatus he was able to find trichlorofluoromethane present.

01:01:40 He said correctly that this was a very good way of tracing the motions of air as the air went back and forth.

01:01:51 But it was that knowledge that this compound was there in the atmosphere that triggered the question,

01:01:59 here's something that mankind has put in, can we figure out what's going to happen to it?

01:02:05 It was that that started us out.

01:02:10 One of the consequences of that was that the calculations that Mario and I did

01:02:18 showed that we could expect in the atmosphere, and this will be the next slide,

01:02:24 that there should be a vertical distribution of these chlorofluorocarbons.

01:02:30 If you actually went to the stratosphere and made measurements,

01:02:33 then you should find that as soon as you got in the stratosphere that the concentrations began to decrease.

01:02:38 That was in 1974.

01:02:40 In 1975, two research groups in Boulder, both of which Susan is representing here today,

01:02:48 made measurements that confirmed that the chlorofluorocarbons did get into the stratosphere and did decompose there.

01:02:56 You were looking at the cause, and so immediately there was evidence of an effect.

01:03:01 It was clear that they got up there.

01:03:04 Then I think the place I would jump ahead is to the Antarctic ozone hole,

01:03:10 which was the big change in the whole picture.

01:03:15 That was first discovered by the British Antarctic Survey people, by Joe Farman,

01:03:21 but the place that most people have seen it is in the results coming from the total ozone mapping spectrometer of NASA.

01:03:29 The next slide will show a measurement made in October of 1979.

01:03:35 This is an instrument that sent back hundreds of thousands of measurements of ozone every day for 15 years,

01:03:42 starting in late 1978.

01:03:45 What this is, is putting those numbers into a color code,

01:03:51 in which on this graph, the picture here, South America is at 1 o'clock, if you look at that as a clock face.

01:03:59 Antarctica is, of course, right there in the middle.

01:04:02 The blue color on that showed that it was between 250 and 275 Dobson units at that time.

01:04:08 A Dobson unit is about one part per billion.

01:04:11 300 is average for the world.

01:04:14 Progressively, over a period of time from 1979, the next one will show 1983.

01:04:21 That's maybe 1987.

01:04:27 It jumps ahead eight years.

01:04:29 What you see is that, in fact, instead of 250 to 275, the low value was of the order of 125.

01:04:38 It was this progressive development over the period of time of eight years that said something very strange had happened over Antarctica,

01:04:46 and it very much needed investigation.

01:04:48 The smoking gun.

01:04:49 At that time, Bob Watson was working for NASA and was in charge of putting together the experiments to try to investigate this.

01:05:00 Bob got a group of four scientific research groups, and he put Susan in charge of it.

01:05:08 Susan took this group to Antarctica in 1986 and again in 1987.

01:05:14 Rather than have me tell you what she did, why don't you have her tell you?

01:05:18 You were 30 at the time.

01:05:21 For all these students out here watching, what an exciting thing to do at the beginning of your career.

01:05:26 Going to Antarctica is exciting at any stage in one's career.

01:05:29 It's a wonderful, wonderful place.

01:05:31 What happened when you got there?

01:05:33 I'd like to start by showing you the historical data from the British Antarctic Survey.

01:05:38 I have a slide illustrating that.

01:05:41 They've been measuring total ozone in Antarctica since about 1957.

01:05:47 For about the first 20 years or so, you see some variability.

01:05:51 We were asked by a caller earlier in the show about natural variability.

01:05:54 You can certainly see that in Antarctica, but you can also see that sometime around the mid to late 70s, the ozone began dropping.

01:06:01 By 1985, it was down to about two-thirds of what it had been earlier.

01:06:07 Now it's down to less than a half of what it had been earlier in the month of October, which is Antarctic spring.

01:06:13 There were a lot of theories about why this was happening, but clearly whatever theory one uses has to make use of the fact that it was only happening to that extent in Antarctica.

01:06:24 I want to just show you what those polar stratospheric clouds that we talked about earlier actually look like.

01:06:30 They're very beautiful, very highly colored clouds.

01:06:33 In fact, sometimes at sunset, they're really quite spectacular.

01:06:37 They look like little rainbows.

01:06:39 Those clouds allow surface chemistry to take place, which activates the chlorine and makes it much more damaging to ozone than it would otherwise be.

01:06:48 That happens most efficiently in Antarctica because it really is the coldest place on Earth.

01:06:53 The mission that I led to Antarctica started out in New Zealand.

01:06:59 This is just a picture of the group getting ready to get on the airplane.

01:07:03 The airplane that took us to Antarctica was a ski-equipped C-130, which flew about nine hours and landed on the snow.

01:07:11 This picture was taken August 22, 1986.

01:07:15 That's the end of the Antarctic winter, and the ozone hole is just about to develop.

01:07:20 One of the things that was measured was chlorine monoxide.

01:07:25 We talked already quite a bit about chlorine monoxide earlier, but this just shows you a composite not only of the aircraft data by the Harvard University group to discuss,

01:07:34 but also ground-based microwave measurements by the group from the State University of New York at Stony Brook.

01:07:41 You can barely see the line at the left-hand side there showing you what you'd expect to see if only gas phase reactions were happening in the stratosphere.

01:07:48 The chlorine would be very, very low.

01:07:50 What you actually see is about 100 times that level.

01:07:54 It's enhanced in a very specific altitude range from about 12 to 24 kilometers, which is the coldest part of the Antarctic stratosphere,

01:08:01 exactly the height range where the clouds are observed to occur.

01:08:05 Let me just then quickly compare this chlorine monoxide profile to the ozone profile that we also observed.

01:08:11 A group from the University of Wyoming did this work, showing you the ozone profile at the end of August still looking quite normal,

01:08:18 but by early October, basically all the ozone was gone between 15 and 20 kilometers, and about, as I said, about 30 to 50 percent of the column was removed.

01:08:28 That's kind of an altitude picture that allows you to see how the chlorine monoxide depletes the ozone in height,

01:08:36 just as we showed earlier the chlorine monoxide versus ozone with latitude.

01:08:41 You can really look at it in many, many different ways and strengthen your picture.

01:08:45 To me, it's really quite ironic that the coldest and most remote place on Earth

01:08:50 also happens to be the first place that ozone depletion was definitively measured, and it's associated with chlorofluorocarbons.

01:08:58 You would think of it as being over a city or something.

01:09:02 The average Joe.

01:09:04 One would guess that.

01:09:06 Now, Dr. Watson, your fingerprints have been all over this research as it develops,

01:09:11 and then suddenly you have someone like Susan who's finding out just how bad this hole is.

01:09:17 How does this reflect in policy?

01:09:19 There's no question that the research of Mario Molina, Sherry Rowland, Susan Solomon, and others

01:09:25 have had profound implications on the political process and on society at large.

01:09:30 The first thing that the work of Sherry and Mario did was to stimulate a major research program literally throughout the world.

01:09:36 Not only government programs, but industry put a significant amount of effort in trying to gain and improve scientific understanding,

01:09:43 and to a large extent, these programs were actually well coordinated nationally and internationally.

01:09:48 As we've already talked about on this program, the consequences for society of ozone depletion

01:09:54 are increased levels of ultraviolet radiation at the Earth's surface,

01:09:58 and this can have significant adverse consequences for human health.

01:10:01 An increase in melanoma and non-melanoma skin cancer, a suppression of the immune response system, and an increase in eye cataracts.

01:10:09 While eye cataracts may not be a big deal in the United States, in Africa it's the major leading cause of blindness.

01:10:15 In addition, increased ultraviolet radiation leads to decreased productivity of ecological systems.

01:10:20 So the consequences for society are really quite profound, things we care about.

01:10:24 Basically, the research these people have done have had profound implications,

01:10:28 both at the national and international level on policy formulation,

01:10:32 which basically is regulations on chlorine and bromine-containing compounds.

01:10:37 In the late 1970s, the U.S. government and a few other governments around the world

01:10:42 rapidly banned the use of CFCs as aerosol propellants.

01:10:46 They felt that the use of CFCs as aerosol propellants was not adequate,

01:10:50 and, in other words, the risk to society did not warrant their further use.

01:10:54 So if we use a spray can today, we don't have to feel guilty.

01:10:56 Absolutely. No CFCs in those spray cans, except occasionally with drug inhalants.

01:11:01 If it's absolutely essential to mankind, then we do in some cases still use it.

01:11:05 A very, very small, minute use.

01:11:08 So in the late 1970s, we actually started to ban CFCs in certain uses,

01:11:12 the so-called non-essential uses.

01:11:14 But, unfortunately, industry, being innovative,

01:11:16 rapidly increased the use of solvents, foam-blowing agents, and many other uses.

01:11:20 And so the increase in the atmosphere of the CFCs inexorably went on.

01:11:25 As the scientific knowledge improved, governments and industry started to get concerned.

01:11:30 It no longer became an issue of the scientific community and the environmentalists.

01:11:33 It became an issue for industry and governments.

01:11:35 How was that leap made?

01:11:37 Largely, the governments took the work of people like Sherry, Mario, Susan.

01:11:42 We used both national assessments and international assessments,

01:11:45 where we brought hundreds of scientists together from all stakeholder groups.

01:11:49 They include academia, government scientists, and industry scientists.

01:11:53 And we assessed whether or not these theories that had been proposed were real or not.

01:11:56 By 1985, the governments of the world were convinced that ozone depletion was a real issue.

01:12:02 And there was then the Vienna Convention to effectively protect the ozone layer.

01:12:06 By 1987, we had effectively observed the Antarctic ozone hole,

01:12:11 but we had not fully proven the cause and effect.

01:12:14 And in 1987, the governments of the world agreed there should be legislation

01:12:18 to limit the amount of fluorocarbons and halons.

01:12:21 They're the bromine compounds put into the Earth's atmosphere.

01:12:24 When we listen to this story today, it sounds so dramatic

01:12:27 how in a relatively short period of time, something that has been in our environment so pervasively,

01:12:34 and industry is using, could be limited and an agreement could be made.

01:12:39 Is this fairly dramatic?

01:12:40 It's both a short and a long time.

01:12:42 In some respects, you could argue we waited too long.

01:12:45 We waited until we proved that fluorocarbons were destroying stratospheric ozone.

01:12:50 Hence, we will have ozone depletion with us for at least half a century.

01:12:54 Some people could argue that we should have taken the work of Sherry, Mario, and others

01:12:59 and acted much quicker.

01:13:00 But isn't it tough to get a consensus politically?

01:13:03 Very tough.

01:13:04 And on the ozone issue, in some ways it was simple.

01:13:07 There was only 19 manufacturers of CFCs across the world.

01:13:10 But they had very important uses, as has already been said.

01:13:13 They're totally non-toxic, so they were safe to society.

01:13:16 They were a safe refrigerant.

01:13:18 So in some ways, it was a major challenge.

01:13:20 And this is always the balance we scientists and policymakers now have.

01:13:23 How much evidence do you need before you enact either national or international regulations

01:13:27 to protect society from environmental damage?

01:13:30 And it's a real challenge.

01:13:31 And you're the guy who has to explain it on a policy level to those who make the decisions.

01:13:36 One amongst many, many hundreds.

01:13:37 It's a combination of politicians in Congress, within the administration, scientists, industry,

01:13:43 and at an international level.

01:13:44 The key issue here is a global issue.

01:13:46 No one country alone can move on its own.

01:13:49 Therefore, this is an issue of how both the developed and the developing countries can move ahead.

01:13:53 I'm thinking about some of the people in our audience who may be choosing a career.

01:13:57 This certainly would be a different kind of chemistry career.

01:14:00 But certainly one that would make great change in the world.

01:14:04 It's crucial that the scientific community learns to communicate in an understandable way

01:14:09 to policymakers and industry and environmental organizations.

01:14:13 It takes all stakeholders together to move forward so you can have economic growth

01:14:17 and environmental protection.

01:14:20 Okay.

01:14:21 Well, it's time to take phone calls from the audience again.

01:14:23 Remember, this is your part of the program.

01:14:26 We want to hear from you.

01:14:27 Please give us a call at 800-368-5781 or 5782.

01:14:32 And for local callers here in Washington, D.C., it's 202-463-3170.

01:14:38 Be sure to tell the volunteer who answers the phone your site number and location.

01:14:42 We have a call now from Carson, California.

01:14:45 Would you like to ask a question of our panelists?

01:14:48 Hello, yes.

01:14:49 My name is Hwang Pham from the California Academy of Math and Science.

01:14:53 And I understand halon production in the U.S. ended in 1993 because it contained bromine,

01:14:59 which contributed to ozone depletion.

01:15:02 What makes bromine more effective in destroying the ozone layer than chlorine?

01:15:10 Susan?

01:15:11 Sure.

01:15:12 And, again, any one of us could have answered that question.

01:15:14 It's a very good question, though.

01:15:16 For anyone who's taken basic chemistry, you know that fluorine is more tightly bound than chlorine

01:15:22 so that when you add the CFCs to the stratosphere, the fluorine ends up being tied up in HF.

01:15:28 Hydrochloric acid is less tightly bound than HF,

01:15:31 so the chlorine is free to some extent and gets even freer when it can hit the surface of a polar stratosphere cloud.

01:15:37 Bromine is not very tightly bound at all,

01:15:40 so basically every molecule of halon that you put in ends up yielding the active form of bromine to a very great extent,

01:15:50 therefore being much more damaging to the ozone layer than the chlorine or fluorine would be.

01:15:55 Okay.

01:15:56 The calls are piling up.

01:15:57 We've got a call from Argonne, Illinois.

01:15:59 You have a question for our panelists?

01:16:01 Hello.

01:16:02 This question is directed to Dr. Fowler.

01:16:04 What effect does the space shuttle have and FST flights have on ozone depletion?

01:16:12 I'd actually like to pass that one to Dr. Watson, if I may.

01:16:16 I believe the question was what is the influence of supersonic transport?

01:16:20 The space shuttle in particular.

01:16:21 The space shuttle.

01:16:22 Okay.

01:16:23 We do have to care about both the space…

01:16:24 Since you are our government representative…

01:16:26 Not only a government representative, I once worked for NASA.

01:16:29 The amount of chlorine that is emitted by the space shuttle per flight is extremely small,

01:16:35 and therefore although the space shuttle does indeed contribute chlorine directly into the stratosphere

01:16:41 and hence adds to the chlorine loading,

01:16:43 the amounts it adds are absolutely minuscule,

01:16:46 and even if you did a calculation, it would be far less than one-tenth of one percent ozone depletion.

01:16:52 So you're right.

01:16:53 We should care about the effluence of space shuttle,

01:16:55 but to be honest, they're so small, they're insignificant.

01:16:58 If, of course, we had space shuttle flights once a day,

01:17:01 then we would have to indeed care about the chlorine that was emitted from the rocket boosters.

01:17:07 And another caller from Flint, Michigan.

01:17:09 You have a question for our panelists?

01:17:11 Yes.

01:17:12 In your opinion, is the U.S. investing enough money in basic research,

01:17:16 not only in your field but in all areas of science?

01:17:20 Well, we'll be talking to Dr. Watson about that in a minute, but Dr. Molina?

01:17:24 Yes.

01:17:25 Well, I am indeed worried about budget cutting in recent times.

01:17:30 I think it's important to continue investing in research about how the entire Earth system functions,

01:17:38 and we are worried that some cuts to some of the federal agencies,

01:17:43 perhaps trying to protect basic versus applied research,

01:17:46 actually is not being done sufficiently carefully to really ensure that we continue to understand how the Earth functions.

01:17:54 Well, Dr. Bresley, you might have something to add.

01:17:56 Yes.

01:17:57 We've been very much concerned about this because the basic research,

01:18:01 it's sort of a thing that people say about everything, but this one I think is really true.

01:18:06 Basic research is the seed corn of our future economic strength.

01:18:09 The United States is not going to be, we hope, the low-salary producer.

01:18:14 We don't expect to do that.

01:18:15 That's not our future.

01:18:16 Our future is going to be being the high-technology society,

01:18:19 and if we're not the high-technology society, I think we're going to get into trouble.

01:18:22 So the question is how do we do that?

01:18:24 We've got to do it with basic research, and the government has a major role to play

01:18:28 because basic research often produces results that some one company can't anticipate would contribute to their profit.

01:18:35 In fact, sometimes the basic research creates the companies.

01:18:38 Discoveries are made that create whole new industries.

01:18:41 So there's no industry waiting to support that stuff.

01:18:43 And it saves humanity like these guys.

01:18:45 That's right, and so it is absolutely critical.

01:18:46 Not to mention that.

01:18:47 It's absolutely critical that the federal government continue to support it.

01:18:50 Now, they've got to balance the budget, but they can't end up with a balanced budget

01:18:53 and a deficit account in our future.

01:18:56 All right.

01:18:57 Dr. Watson's from the White House.

01:18:58 Very quickly, how tough a sell is it?

01:19:00 There's no question this administration cares very much about both basic and applied research and technology development.

01:19:06 In the area of environment and natural resources alone, we spend about $5 billion a year.

01:19:11 My belief is we need to spend even more.

01:19:14 And at this moment, there's an ideological split between the administration and the Republicans in Congress

01:19:19 who do not believe that the government has such a large role in either basic research or in technology development.

01:19:25 I believe we need to spend more money both in basic research and the National Science Foundation and NIH

01:19:30 and also in the more applied agencies like NASA, NOAA, DOE.

01:19:35 It's essential that that research is competitive and the university scientists get this money

01:19:40 so they can understand our environment, and that will allow us economic development.

01:19:44 In tough budget times, though.

01:19:45 It is tough, I guess.

01:19:47 We can't afford not to invest in this type of research.

01:19:49 Okay, good.

01:19:50 We've got the last word from you.

01:19:51 Arlington Heights, Illinois, you have a question?

01:19:53 Yes, from World Research University.

01:19:56 And we have a question.

01:19:58 Other than the halting of production and patiently waiting,

01:20:01 is there anything that can be done to speed up the breakdown of these harmful molecules?

01:20:06 And if not, what research is being done?

01:20:11 Who wants to take that?

01:20:14 No one has devised a good scheme for destroying the chlorofluorocarbons in the atmosphere,

01:20:23 and it doesn't seem very likely that they will.

01:20:27 These compounds were manufactured to be inert, unreactive,

01:20:35 and finding something that you can put into the atmosphere or shoot through it

01:20:39 that will affect only the unreactive materials and not any of the other compounds

01:20:44 is a very daunting chemical task.

01:20:46 And with 20 years of experience on it,

01:20:48 no one has come up with a good attack that would come even close

01:20:55 to getting rid of the chlorofluorocarbons from the atmosphere

01:20:58 on a scale relative to what happens to it naturally.

01:21:01 2% of the chlorofluorocarbon-11 goes away naturally every year,

01:21:05 and about 1% of fluorocarbon-12.

01:21:08 That means that they will last for 50 or 100 years,

01:21:11 but that's still a very large amount of material being eliminated regularly every year.

01:21:16 Okay, another caller from Anacartes, Washington.

01:21:20 Do you have a question for one of our panelists?

01:21:22 Yes, earlier I think we understood you to say that CFC levels have peaked out or stabilized,

01:21:30 and then Dr. Watson mentioned that there may be cataracts and cancers

01:21:34 and things like that resulting from ultraviolet light.

01:21:38 I have heard that amphibians may be threatened with extinction in some places,

01:21:43 but perhaps because of ultraviolet light damage to the eggs,

01:21:47 can we anticipate making some other unpleasant discoveries

01:21:53 about what ultraviolet light might do to the surface of the earth

01:21:56 and what would have happened if you folks hadn't gotten involved

01:22:02 in policy changes to reduce CFCs?

01:22:05 That's the scary side.

01:22:07 That's a difficult question.

01:22:08 Perhaps I could start by saying not enough research has been really carried out

01:22:12 to understand all the possible effects of increased ultraviolet radiation at the earth's surface.

01:22:18 The community that studies these effects is actually rather small.

01:22:22 So what we have is at least a few very clear examples of damage to biological systems,

01:22:29 and that was sufficient to really make sense out of phasing out the CFCs.

01:22:34 But indeed, we do have a worry as to what will actually happen to many of these systems.

01:22:39 Unfortunately, it's very difficult to establish clearly whether what is happening to amphibians

01:22:46 is actually coming from increased levels of UV.

01:22:49 It could be multiple stresses, but that's certainly no excuse not to do something about this problem.

01:22:55 So I'm certainly all for continuing research on the ecology, how it functions,

01:23:01 and how it can be affected by ultraviolet radiation.

01:23:04 Dr. Rowland.

01:23:05 If we can call up the slide that shows this.

01:23:09 This shows ultraviolet measurements that have been made in three locations.

01:23:17 One of them is in San Diego, California.

01:23:20 One of them is on Palmer, which is in the Antarctic Peninsula,

01:23:24 and the third is at the South Pole.

01:23:26 All of these measurements were made in 1993,

01:23:29 and they're measurements taken for the peak of one particular day.

01:23:34 And on that one particular day there, which was October 26th of 1993,

01:23:40 the intensity of the ultraviolet radiation in the Palmer Peninsula, that is in Antarctica,

01:23:46 was greater than on the most intense day in San Diego.

01:23:50 The South Pole results are the most intense day in the South Pole, which are not as great as San Diego,

01:23:55 but the fact that we have, on occasional times now, in Antarctica,

01:24:00 ultraviolet radiation that's more intense than you have in Southern California

01:24:04 says that the conditions in Antarctica have changed very, very sharply as a result of the Antarctic ozone hole.

01:24:12 It's those conditions which may affect the biology in the Antarctic region,

01:24:19 and we have ozone depletion also in the northern hemisphere not as serious as that,

01:24:27 and so we have to be concerned about ultraviolet effects in the north temperate regions as well.

01:24:33 And a question from Elk Grove, Illinois. A question?

01:24:37 Hello, this is Elk Grove High School.

01:24:39 We would like to know at the current rate of depletion,

01:24:42 approximately how many years would it take for the ozone layer to be depleted

01:24:46 to the point of seriously affecting the typical American lifestyle,

01:24:50 and is there any hope at all of having high levels returned?

01:24:56 It's for you all.

01:24:57 Yes, perhaps I'll start the game here by first explaining that

01:25:01 ozone is continuously being produced by the sun and continuously being destroyed,

01:25:05 so the timescale for this production destruction process is relatively fast

01:25:10 compared to the timescale for the presence of CFCs in the atmosphere.

01:25:14 So that's why what we expect to happen is when the CFCs slowly disappear at the rates that we just heard,

01:25:21 namely 50 to 100 years, the ozone layer will recover

01:25:25 because ozone will be replenished by its annual production from the sun.

01:25:30 In the next decade or so where the chlorine levels will be largest,

01:25:36 it's going to be difficult to predict what the levels of ultraviolet radiation will be.

01:25:42 For example, in the northern hemisphere, we could have some very bad years if it's cold like this last year,

01:25:47 and perhaps others will be not so bad,

01:25:50 but we expect at least that we put a cap on ozone depletion if we take a long-term view.

01:25:57 We have an illustration here that we frequently use to try to explain it

01:26:04 because ozone is made all the time and goes away all the time,

01:26:09 and so the analogy we use here is that if you had a bathtub in which the tap was open and the plug was open,

01:26:18 water would be running all the time into the tub, water would be running out of the tub,

01:26:23 and there would always be some there,

01:26:25 and what we've done in the equivalent by putting in the chlorine is to open another hole in the tub,

01:26:31 and the tap is still running, both holes are open, we're always going to have water in the tub,

01:26:37 and it's going to continue that way until we close that hole that is caused by the chlorofluorocarbons,

01:26:43 and the way to close that is to get rid of them, but that time scale is 50 to 100 years.

01:26:48 But we're not going to get rid of ozone.

01:26:51 Ozone is being made all the time.

01:26:53 We're going to have ozone, it's just we're going to have less of it until the chlorofluorocarbons are gone.

01:26:57 And that was a very good question because that's what the average Joe is thinking,

01:27:00 and that's the first chart I've understood today.

01:27:03 Cuthbert, Georgia.

01:27:05 Do we have another question?

01:27:07 Yes.

01:27:08 Has there always been an ozone layer, and are there any theories on how it formed initially?

01:27:17 Dr. Molina.

01:27:18 Sure.

01:27:19 Anyone of us, again, can answer this question.

01:27:22 Before there was an ozone layer, of course, oxygen had to be present in the atmosphere,

01:27:27 and that resulted out of life moving to the Earth's surface.

01:27:32 But for life to evolve the way we know it, the ozone layer really had to be formed.

01:27:38 And we know how it was formed.

01:27:40 It's by this process that I explained earlier of high-energy radiation from the sun breaking oxygen molecules and making ozone.

01:27:48 And so this mechanism was present very early on, and, again, it allowed biology to evolve at the Earth's surface

01:27:57 because in the presence of this very harsh ultraviolet radiation, the molecules that make life would have been easily destroyed.

01:28:06 Let's take a look at the future, the future in policy, the future, some of the projects you're working on right now.

01:28:14 Have you found anything else that's going to destroy humanity that you'd like to tell us about today?

01:28:20 Dr. Rowland, do you want to start?

01:28:22 Well, my own research group has been concerned very much lately about what's going on in the lower atmosphere.

01:28:30 From the standpoint of the research scientist, there are lots of things that are very interesting.

01:28:36 And now that we have the ability to analyze what's in the atmosphere, and as we increase that ability, we can start looking at different questions.

01:28:46 And some of these questions have to do with the gases that come out of the ocean from oceanic biology.

01:28:52 Others of these questions, as I mentioned briefly earlier, had to do with what comes out when you burn the agricultural wastes in South America and in Africa,

01:29:01 or if you're clearing the forests in order to make room for agriculture.

01:29:06 There are a lot of chemistry that goes on, and so that is now accessible to us, and it is those areas that we are particularly interested in.

01:29:16 One last thing is that we can't analyze what's present in the cities, and as pollution becomes a more increasing problem all over the world,

01:29:27 we become fascinated with trying to see what we can do about pollution in cities like Los Angeles and Mexico City and Johannesburg, and so on.

01:29:37 Okay, and Dr. Watson?

01:29:39 There's one other major issue that we have to contend with, with respect to ozone depletion,

01:29:43 and that is effectively whether the advent of the supersonic transportation, supersonic aircraft, could potentially lead to a loss of stratospheric ozone.

01:29:52 Aircraft companies in Europe, North America, and Japan, super-type of concourse, much larger airplanes flying at a faster speed, flying at a higher altitude.

01:30:02 At this moment, one of the real research challenges is to see whether these planes can be economically viable and whether they will be environmentally safe,

01:30:09 so that's one key challenge with respect to ozone depletion.

01:30:12 The other issues which are very, very important for society are climate change, human-induced climate change, our energy policies and land-use policies.

01:30:20 Are you talking about the greenhouse effect?

01:30:21 The greenhouse effect. Are we changing our climate?

01:30:23 It has profound effects on socioeconomic systems, ecological systems, and human health.

01:30:28 And the other big issue is the loss of biological diversity.

01:30:31 We're losing species, we're losing genetic variability, and we're changing our ecosystems.

01:30:36 This could have profound effects on the way our society evolves, our sources of food, medicine, fiber,

01:30:42 and the way we have clean air, clean water, and the way effectively we control our whole environment.

01:30:47 This whole CFC issue seems to have been addressed fairly quickly,

01:30:51 although you say it should have been faster than 20 years that we had an international policy.

01:30:55 But does that give you any hope that as we address these other issues, there will be the consensus,

01:31:01 and that there's an enlightenment on the part of countries that they've got to start putting in some regulations and watching things more closely?

01:31:08 I have mixed emotions.

01:31:10 I believe that there is a reasonable amount of research being done to try and understand the issue,

01:31:14 so I believe the scientific community is doing its part to try and understand and improve knowledge.

01:31:19 We have to recognize, though, that ozone depletions are a much simpler scientific and political and technical issue.

01:31:26 And yet a smoking gun, the whole.

01:31:28 Yes, climate change is much more complex politically.

01:31:30 You would have to change the energy policies of the world and the land use policy of the world.

01:31:34 Loss of biodiversity has to get to grips with, again, poverty, terrible poverty in some parts of the world, and land use practices.

01:31:42 I'm optimistic we now have international conventions on biodiversity and on climate,

01:31:47 but there's a big step between having a framework convention that says we should try and limit climate change,

01:31:52 limit the loss of biological diversity, and solid actions by governments to really move in the right direction.

01:31:58 We are moving in the right direction, but it's slowly.

01:32:01 And the clock is ticking away.

01:32:02 The clock is definitely ticking.

01:32:03 Okay, we have a call from Austin, Texas.

01:32:05 Would you like to ask a question of one of our panelists?

01:32:08 Yes, this question is for Dr. Rowland or Dr. Molina.

01:32:11 In 1974, you proposed that CFCs would further disassociate if exposed to UV radiation.

01:32:19 How did you prove this?

01:32:23 Dr. Rowland?

01:32:24 The measurements that show that these compounds break apart with absorption of ultraviolet radiation is something that's very standard in the laboratory.

01:32:35 If you have an ultraviolet source and every laboratory has an ultraviolet spectrometer,

01:32:41 then you put in measured amounts of the chlorofluorocarbons and see whether the light gets through.

01:32:48 And what you find is that these compounds absorb.

01:32:51 And then, in addition, you look to see whether you get the products.

01:32:55 And if that happens in the laboratory, then it's also going to happen for the same molecules when exposed to the same wavelength of light up in the stratosphere.

01:33:05 And we have a call from Duarte, California, from Baxter Healthcare.

01:33:09 Yes, we're hosting some high school students as part of our Earth Day celebration.

01:33:12 Good for you.

01:33:13 And this question is from Arcadia High School.

01:33:16 Is there any relationship between the Gaia hypothesis and the depletion or the holes that have formed in the ozone layer?

01:33:24 I was just about to ask that question.

01:33:26 Dr. Molina.

01:33:28 Well, the Gaia hypothesis, if I can sort of summarize it, it states that the Earth has a mechanism, feedback mechanism,

01:33:37 so that it protects itself from any damage that you do to it.

01:33:41 And that does not necessarily include preserving the human species.

01:33:45 But if you look at it in general, if you look at the details, the Gaia hypothesis is really more poetry than science.

01:33:53 Of course, we do understand many of these feedback mechanisms.

01:33:56 We understand the details.

01:33:58 But there are limits to this concept that the Earth functions as a living organism.

01:34:03 So from a practical point of view, we still have to do the same job, namely understand the science very well

01:34:08 and take some specific actions to try to prevent damage to the Earth system.

01:34:13 Dr. Rowland.

01:34:14 Yeah, I'd make just a comment that they also owe, both of those owe something to Jim Lovelock

01:34:20 because Jim Lovelock was the one that invented the electron capture detector that allowed the detection of the chlorofluorocarbons.

01:34:26 And he's also the creator of the Gaia hypothesis.

01:34:29 And if you just look at what's in the Earth's atmosphere, you realize that it is controlled by biology,

01:34:35 that the composition of our atmosphere is very strongly reflecting the fact that there are all these living creatures down at the surface of the Earth.

01:34:44 Okay, another call from Galesburg, Illinois.

01:34:47 This question is for Dr. Rowland.

01:34:49 What method do you use to collect air samples and detect CFC concentrations?

01:34:55 We take – we will – we have stainless steel canisters in the laboratory,

01:35:01 which we can evacuate and take to a remote location, and you open it up and collect it there.

01:35:09 So if we're collecting individual samples, then we just open it to atmospheric pressure, whatever it is there.

01:35:16 If we're going toward the airplane, because we go to higher altitudes, we need to be sure we get enough samples,

01:35:20 so we have pumps that pump the air into that.

01:35:23 But then the analysis is done back in the laboratory,

01:35:25 and some of that analysis was shown in the clips from my laboratory at the beginning.

01:35:31 I've been wondering as I'm sitting here.

01:35:33 We wake up, the rest of us, and go to work and, you know, see our family and take care of our kids,

01:35:39 and you all see so many things that we don't see.

01:35:44 And you have communicated to the world a problem and have changed the environment that we live in because of your work.

01:35:51 What is your sense for the future?

01:35:53 We've had a lot of questions based on sort of fear.

01:35:56 There is fear out there.

01:35:57 When someone hears you talking about this, something that you deal with every day, it sounds very –

01:36:03 you're comfortable talking about it, you're comfortable, you've accepted it.

01:36:06 Do you see us two or three generations down the road, are we going to be okay?

01:36:12 I mean, this is scary stuff for the average person.

01:36:15 Well, here again, I would also have mixed emotions about this.

01:36:18 On the one hand, I'm an optimist, and again, looking at the stratospheric ozone problem,

01:36:24 we see that there are ways in which society can actually solve this type of global problems.

01:36:30 Different segments of society talk to each other, industry, scientific community, policymakers, and so on.

01:36:36 So things can be done.

01:36:38 On the other hand, we are really facing some enormous challenges.

01:36:41 If we consider some of the problems we were talking about just a minute ago,

01:36:45 if you consider, of course, that developing countries are going to continue developing,

01:36:49 and, of course, population is going to continue increasing.

01:36:52 We really need to change things in a very significant way.

01:36:55 It cannot be the case that they use energy the same way that Western civilization has done it up to now.

01:37:02 So it's going to be very important that we consider the health of the entire planet

01:37:06 and that we begin to move very soon in the right direction.

01:37:10 Senator Watson is nodding profusely.

01:37:12 Do we need, though, sort of a grassroots understanding of this?

01:37:15 Should these guys be on Oprah?

01:37:16 I mean, do we need the general public to be more aware of these things?

01:37:19 Yes, absolutely.

01:37:20 The general public must be part of understanding the issues and hence be part of the solution.

01:37:25 This morning I was meeting with a number of people from China

01:37:28 talking about an issue called sustainable development.

01:37:30 How can we have an increase in population?

01:37:33 How can we have an increase in economic growth and yet live in a sustainable world

01:37:38 so future generations have the same natural resources as we have today?

01:37:42 And the answer is we can move there.

01:37:44 We do have to take care of population growth.

01:37:46 We can also have economic increases, which we must have in developing countries from an equitable standpoint.

01:37:52 We have to use technologies much wiser.

01:37:54 We have to use renewable energies rather than fossil energies, and that's certainly possible.

01:37:58 We've got to stop producing waste, and we have to have pollution prevention.

01:38:02 I think if we can bring together government, industry, and society at large,

01:38:07 we can solve these problems, but it needs forward planning,

01:38:10 and all the stakeholders have to be involved, the science community, industry, and government, and the local person.

01:38:16 Right, the person who votes.

01:38:18 San Francisco, California, we have a question.

01:38:22 Good afternoon.

01:38:24 Dr. Rowland, earlier you mentioned the TOMS, or the Total Ozone Mapping Spectrometer.

01:38:32 I understand from our studies here that the Nimbus-7 satellite on which it resides is basically out of commission,

01:38:40 and so those observations are no longer possible.

01:38:43 And I'm wondering what's going to replace the loss of the information provided by TOMS,

01:38:49 and without that dramatic graphic representation, are we going to be okay?

01:38:55 The TOMS instrument was designed to last for a year or possibly two, and it went almost 15.

01:39:02 So that was a remarkable success on the part of NASA.

01:39:06 A second instrument that was put up on the Meteosat, that is a Russian satellite, lasted for about its two-year design.

01:39:15 There's another one ready to go as soon as we have a launcher in there.

01:39:18 But meanwhile, there are other satellites that can make measurements of ozone, not as many as the TOMS instrument,

01:39:25 but sufficient that we are able to track what's going on.

01:39:30 And, of course, we always have these ground-based measurements at the established stations.

01:39:35 So we don't have the same graphic pictures that TOMS provided for us for 14 or 15 years,

01:39:42 but we do have measurements of ozone that are going on and tell us what's happening.

01:39:46 Okay, Alton, Illinois, you have a question?

01:39:48 That's right. We're calling from Pensypia College, and we had a question for Roland and Molina.

01:39:53 And we were wondering if you could talk to them about the proposed solution by Alfred Wong at UCLA.

01:39:59 He proposed a blimp charged with chlorine-free radicals,

01:40:06 and that would somehow pick up some of the harmful chemicals in the ozone.

01:40:10 And we're wondering if you could talk to them about that.

01:40:12 What about the blimp idea, Dr. Molina?

01:40:14 I guess I would give again the same answer I gave before.

01:40:17 I did discuss years ago the details of the solution with Professor Wong,

01:40:22 and from my point of view, he was really miscalculating what is needed to prepare the ozone layer.

01:40:28 So if you look in great detail realistically at what has been done,

01:40:31 I don't think it's coming anywhere close to solving the problem.

01:40:36 His idea was actually a bit more complicated.

01:40:39 He was trying to move the chlorine atoms with some electric fields, first ionizing them and so on.

01:40:44 If you really begin to compute the amount of energy that you need to do this, it just doesn't work.

01:40:50 I would add that the atmosphere is bombarded constantly by cosmic radiation

01:40:58 and by natural radioactivity that's drifting out of the earth,

01:41:03 so that we're creating ions all the time in the atmosphere.

01:41:07 We're knocking electrons loose.

01:41:09 And that happens throughout the troposphere.

01:41:12 It happens throughout the stratosphere.

01:41:15 Thousands of ions, thousands of electrons are being knocked loose in every cubic centimeter every second.

01:41:21 And so the atmosphere is constantly bombarded in that way,

01:41:25 and it isn't taking the chlorofluorocarbons out.

01:41:28 So the onus on somebody suggesting that by adding electrons you can clean the atmosphere

01:41:34 is that they have to demonstrate how you can compete on a global scale.

01:41:41 And I haven't seen anything that comes anywhere close.

01:41:43 Too bad. It sounded like a neat idea.

01:41:45 Redwood City, California. You have a question?

01:41:48 Yes, hi. I have a two-part question.

01:41:51 We were wondering that if the Wong process is not feasible,

01:41:54 are there any other things being researched now that might speed up the taking out of these chlorine atoms from the atmosphere?

01:42:03 And our second question is whether you have any advice for students

01:42:07 if they want to help address this or other serious environmental problems.

01:42:11 For example, do you recommend certain schools or programs?

01:42:16 I think it would be inappropriate to recommend certain schools or programs.

01:42:22 That's something that you need to investigate.

01:42:25 I think what one should say is that there are hundreds of scientists in the United States,

01:42:31 thousands if you go around the world, that are very competent scientists that are working on these problems.

01:42:37 And what you need to do is to ask questions to find out which of these that you might like to work with.

01:42:43 If a thousand scientists all wanted to work with Mario, that would be very hard on Mario.

01:42:48 It would be better for one of them to work with Mario and one with each of the thousand others

01:42:53 so that they could get some close study and learn how to do science.

01:42:59 That would be my answer.

01:43:01 I think the educational system in the United States is strong enough that you can go to many universities

01:43:07 and get good environmental applications, good techniques.

01:43:13 And you may not want to work on ozone depletion.

01:43:16 You may want to work on the problem that's going to be important in the year 2010.

01:43:21 And that means you have to get a very good education and start asking your own questions.

01:43:26 If I can add just my own advice, very briefly, is that this is a fascinating field.

01:43:33 You can combine science, basic science, applied science.

01:43:36 So I would certainly encourage all of you to work in the fields like this that relates environmental issues

01:43:44 to basic science and to benefits to society.

01:43:47 We have another question from Argonne, Illinois.

01:43:50 Hi, Dr. Molina. My name is Tanisha Redmond, and I'm from Hillcrest High School.

01:43:56 Hi, Tanisha.

01:43:57 I was wondering, can the lost ozone artificially be replaced by man?

01:44:02 Well, the short answer is that it's very difficult to replace.

01:44:07 We have concluded in the scientific community that there is really only one solution to this problem,

01:44:13 which is to stop the release of the CFCs and other compounds that affect the ozone layer.

01:44:19 So you have to realize once they get into the environment, they become very dilute.

01:44:23 They are present at parts per billion molecules.

01:44:26 Only one out of every billion molecules has chlorine that gets to the stratosphere.

01:44:32 So it's very, very difficult to recover them once they are there.

01:44:35 But you can tell from these questions that's what everybody wants to do.

01:44:38 Let's fix it. Susan?

01:44:40 Yeah, I'd like to comment on that.

01:44:42 As has already been explained, there are ways to make ozone.

01:44:46 We know how much energy it takes to break up an oxygen molecule and make two ozone molecules out of it.

01:44:52 But it's a lot of energy, and the ozone hole is really big.

01:44:55 It's twice the size of the continent of the United States, and it's the thickest amount ever.

01:44:59 So if we put the United States' largest power plant to work doing nothing but making ozone,

01:45:04 it would actually take 12.6 years to make enough ozone to fill the ozone hole.

01:45:09 Now, that's just from an energy point of view.

01:45:11 It doesn't even begin to address how we would get it up there.

01:45:13 Now, the problem is the ozone hole forms every year, though.

01:45:16 So if we want to fill it every year, we would need about 150 of those power plants.

01:45:20 And you can begin to get a concept of how expensive that would be.

01:45:23 So it's not the case that we don't really, in principle, know how to do it.

01:45:27 It's just that it would be unbelievably difficult to do.

01:45:30 Very good answer, Dr. Solomon.

01:45:32 That really helps to explain the predicament we're in.

01:45:36 Anna Cortez, Washington, you have a question?

01:45:40 I was wondering if there's any information that we can access from this high school about monitoring the ozone.

01:45:55 Through the Internet? Is there any way to pipe into NASA or something?

01:45:59 I would suggest that if you got on the Web and have a good search engine and look for the word ozone,

01:46:06 you would be quite amazed by the number of hits that you would get.

01:46:10 You would find everything from answers to common questions about ozone to last year's ozone to measurements of chlorofluorocarbons.

01:46:18 Just try it. You guys know how to use that kind of stuff.

01:46:20 I'm so envious.

01:46:22 Back when we were doing papers, we had to go to the library and go to these federal agencies.

01:46:26 You don't have to do that.

01:46:27 Elk Grove, Illinois, you have a question for us?

01:46:30 Okay, hi. This is Elk Grove Village again.

01:46:32 It was stated before that you couldn't flush a gas to bond with the CFC, so it didn't bond with the ozone.

01:46:38 Why couldn't you put hydrogen ions into the troposphere to bond with the CFC before it reaches the ozone?

01:46:46 Okay, here again, the short answer is that there are many other things in the atmosphere besides CFCs that are much more abundant.

01:46:53 So if you put something in the atmosphere that is very reactive, that would somehow or other actually be able to attack the CFCs,

01:46:59 it would be destroyed long before it would find the CFC molecule because the CFCs are remarkably stable.

01:47:06 So what you need is something that is very, very selective.

01:47:10 You would need a process that would seek out the few CFC molecules that exist in a given parcel of air, and that's just impractical.

01:47:18 There's no simple way that you can selectively destroy these particular molecules.

01:47:25 Okay, and one last question from Arlington Heights, Illinois.

01:47:29 You have a question for one of our panelists?

01:47:35 We're waiting for your question.

01:47:38 Roosevelt University?

01:47:40 Anybody out there?

01:47:43 Okay, what about Omaha, Nebraska?

01:47:45 Maybe that'll be our last call.

01:47:48 Yeah, we were wondering, did the nuclear bombs or any other nuclear testing affect the ozone layer in any way through radioactive waves?

01:47:56 And talk about maybe volcanoes, too, right?

01:47:59 Okay.

01:48:01 That's a very good question.

01:48:04 People have been worrying about the possibility of ozone depletion from nuclear bombs for a long time,

01:48:10 and that's partly because some of our initial interest in ozone depletion actually had to do with the chemistry of reactive nitrogen,

01:48:17 which can also be enhanced from nuclear explosions.

01:48:20 It turns out, though, that as we've gotten smarter over the years,

01:48:23 we've recognized that the chlorofluorocarbon problem is certainly more acute than the nitrogen oxide problem,

01:48:30 and that, in fact, it's not at all clear that nitrogen oxides, it depends on what altitude you inject them at,

01:48:37 but the depletion from those is going to be small.

01:48:40 The depletion from chlorine is much, much bigger.

01:48:42 We've never really detected any evidence that the nuclear bomb tests of the 60s caused any change in the ozone layer.

01:48:49 I do want to mention, though, Megan referred to the problem of volcanoes, which is very interesting.

01:48:55 Recent work by a number of people, including myself, has now, I think, shown that volcanoes,

01:49:02 which can inject sulfur dioxide into the stratosphere if they're very, very explosive,

01:49:07 actually enhance the amount of surface area everywhere, not just in Antarctica.

01:49:12 So just like the polar stratospheric clouds in Antarctica, volcanic eruptions can enhance chlorine's ability to deplete ozone.

01:49:19 I want to emphasize that nothing would happen without the man-made chlorine,

01:49:22 but with the man-made chlorine there, you do get quite substantial extra enhancement in ozone loss,

01:49:27 even at mid-latitudes after a major volcanic eruption.

01:49:30 Okay, it's unfortunate, but it's time to conclude the discussion.

01:49:33 Before we close, though, I thought we would get a summation from each of you, starting with Dr. Molina, about a minute's worth.

01:49:40 Well, what I would say is that the importance of the CFC and stratospheric ozone depletion issue is that,

01:49:49 first of all, it has really shown us that mankind is quite capable of affecting the environment on a global scale.

01:49:56 The atmosphere of the entire Earth is being affected in this way.

01:49:59 But in second place, it's also shown us that society can actually come together and begin to solve this type of global problems,

01:50:06 and that different countries indeed talk to each other, and that for these very important issues,

01:50:12 there can be international agreements and that they are actually working.

01:50:16 Dr. Rowland?

01:50:17 I think I would emphasize the importance of curiosity, that science depends on individuals thinking about problems,

01:50:27 thinking about questions, that they don't know what the answer is.

01:50:32 And if you go back 20, 25, 22 years or so, at the beginning of this problem,

01:50:39 you'll find that Mario and Susan and Bob were all just in graduate school or undergraduate school at that time,

01:50:46 looking around for what they might do.

01:50:49 I was in that position a few years before that, and the question of what you do depends on whether or not you use your imagination.

01:50:58 And if you do use your imagination, then there's some very exciting things that you can do.

01:51:04 Chemistry is a very creative process, isn't it?

01:51:07 Dr. Solomon?

01:51:08 I'm going to keep my message fairly short.

01:51:11 I think what I'd want to say to students is that if you look at human history,

01:51:16 people have been on this Earth for a long time, a lot of centuries, I guess about 350 of them.

01:51:22 And it's only in this last century that we've finally begun to realize that we can actually modify the planet on a global scale.

01:51:29 In the next century, population growth is going to lead to the need to understand what modifications we can do

01:51:36 and what we can do about it in a very, very acute way that we've never faced before.

01:51:40 I think there's a broad range of environmental problems that are going to be coming our way,

01:51:44 and it's people who are students now who are going to be primed and in position to address those problems in the next 20 or 50 years.

01:51:52 Dr. Watson?

01:51:53 Yes, advances in science and technology will be absolutely essential if our world is to become sustainable.

01:52:00 While scientific knowledge does not answer all of the questions and all of the challenges posed by population growth and growth in economics,

01:52:08 science can inform the policy process.

01:52:11 We need informed scientists working with lawyers, business leaders, economists,

01:52:16 working together so that our world can develop sustainably all the way from the city level, the state level, the national level, and the global level.

01:52:25 Science is going to be very important. We need more scientifically literate people.

01:52:29 Dr. Breslow?

01:52:30 Yes, I think I would say that we don't want mindless fear, and we don't want mindless optimism, as mindlessness is the enemy, really.

01:52:39 What's clear from all of this is that we can actually take a problem, learn about it, and do something about it.

01:52:45 This is not the first one that we've solved, faced and solved.

01:52:48 DDT came up, and it was a wonderful insecticide, and then people discovered there was a side effect of it,

01:52:53 not an ozone effect, but an effect on reproduction of birds.

01:52:57 And at that point, scientists then, knowing that information, addressed the question and did something about it.

01:53:02 It can be done. There's no reason to be fearful of the future.

01:53:06 We certainly can't go back to a world in which we don't have refrigeration to preserve our foods or food or air conditioning.

01:53:11 We don't have to go back to that.

01:53:12 What we have to do is to understand the problem and address it, and you students can contribute to it.

01:53:17 You don't have to be simply passive observers.

01:53:19 There's plenty of room for contribution in the future by scientists studying now, you out there in the audience studying now,

01:53:25 to come in and play a role in trying to use science and technology to make this a better world.

01:53:30 Thank you, Dr. Breslow, and thank all of you for joining us today.

01:53:34 We've come to the end of this ACS Satellite TV seminar.

01:53:37 Thank you all for joining us.

01:53:39 Local site coordinators, please don't forget to complete and return your seminar evaluation forms.

01:53:45 We listen to and need your comments and suggestions.

01:53:48 Our next seminar will be on November 4th, the Monday of National Chemistry Week,

01:53:53 and will be another update for chemical educators on teaching chemistry.

01:53:57 This year, we will focus on including organic chemistry in the introductory course.

01:54:02 We hope that all of the teachers in the audience will join us then.

01:54:05 On behalf of the American Chemical Society Education Division, thanks for watching and have a good day.

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