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Molina wins Nobel Prize for ozone work

The newest Nobel laureate is Professor Mario J. Molina, who won the 1995 Nobel Prize in chemistry for explaining how certain man-made chemicals can rise into the atmosphere and harm the ozone layer that shields us from the ultraviolet radiation of the sun.

The work, which has led to international actions banning the culprit chemicals, "has contributed to our salvation from a global environmental problem that could have catastrophic consequences," the Nobel committee said. Dr. Molina's Nobel Prize represents the first time that the committee has recognized environmental research.

"The ozone story is really a success story," Professor Molina, the Lee and Geraldine Martin Professor of Environmental Sciences, said at a talk last Friday on his award-winning work. "To me, this is a very good example of how the world can work together to get problems solved."

Professor Molina, 52, shares the prize of $1 million with Professor F. Sherwood Rowland of the University of California at Irvine and Professor Paul Crutzen of the Max Planck Institute for Chemistry in Mainz, Germany. The prize was announced last Wednesday.


At an MIT press conference packed with cheering students and colleagues, Professor Molina was lauded not only for his scientific achievements, but for his contributions to society through that work. Colleagues were also quick to note his personal qualities, among them his warmth, honesty and reputation of being considerate to everyone he meets.

The day was capped by a congratulatory call from Vice President Al Gore.

Sitting at the press conference table with Professor Molina was his wife, Luisa, who also conducts ozone research at MIT (she is a research scientist in the Department of Earth, Atmospheric and Planetary Sciences). Professor Molina thanked her "for the continuing support she has given me and for being a true collaborator." Their son, Felipe, is a freshman at Brown University.

Also at the press conference table were Professor Robert J. Birgeneau, dean of the School of Science, and Professor Thomas H. Jordan, head of EAPS. (Professor Molina holds a joint appointment in EAPS and the Department of Chemistry.)

Referring to MIT's recent string of Nobelists, Dean Birgeneau said, "Three in a row is amazing, but when the three have the human qualities of [Clifford] Shull [physics, 1994], [Phillip] Sharp [physiology or medicine, 1993], and now Molina, that is truly remarkable."

Similarly, President Charles M. Vest commented, "We are extremely pleased that such a productive and respected member of the MIT community has won the Nobel Prize in chemistry. This award emphasizes that the most fundamental scientific inquiry can turn out to have extremely important ramifications for our world. It also shows that sometimes nice guys finish first."

Said Professor Stephen J. Lippard, head of the Department of Chemistry: "We're obviously very proud of Mario. This is the first Nobel Prize in chemistry given to an MIT faculty member."


The ozone layer, which exists nine to 31 miles above the Earth, protects living organisms from the ultraviolet radiation of the sun. Without an ozone layer animals and plants could not exist, at least on land. Significant depletion of ozone can cause increased skin cancer, cataracts and immune-system damage in humans.

In 1974 Professor Molina was a postdoctoral fellow in Professor Rowland's laboratory at the University of California at Irvine. That year the two published a paper in Nature outlining the threat to the ozone layer from the chlorofluorocarbon (CFC) gases, or freons, that were being used as propellants in spray cans, as the cooling medium in refrigerators and air conditioners, and in plastic foams.

The two realized "that the chemically inert CFCs could gradually be transported up to the ozone layer, there to be met by such intensive ultraviolet light that they would be separated into their constituents, notably chlorine atoms," the Royal Swedish Academy of Sciences said in announcing the prize. Chlorine atoms were already known to decompose ozone.

As a result, Drs. Molina and Rowland "calculated that if human use of CFCs was to continue at an unaltered rate the ozone layer would be depleted by many percent after some decades." This prediction of an ozone "hole" laid the groundwork for its discovery in 1985 over the South Pole by other scientists.

Molina and Rowland's 1974 paper "created enormous attention," the Academy said. "Many were critical of [their] calculations, but yet more were seriously concerned by the possibility of a depleted ozone layer. Today we know that they were right in all essentials. It was to turn out that they had even underestimated the risk."

Dr. Crutzen shared the prize with Drs. Molina and Rowland for showing, in 1970, that nitrogen oxides accelerate the rate of reduction of ozone. His research was also key to explaining the mechanism behind ozone depletion over Antarctica.

At the MIT press conference, Professor Jordan said, "It's important to realize that Mario's work didn't stop with his landmark hypothesis. With the discovery of the Antarctic ozone hole, he began a second phase of major contributions in this area.

"He sought to understand why it was that the ozone was depleted specifically in the Antarctic, in some of the coldest parts of the stratosphere. And this new phase of his work led to the discovery that the relatively benign chlorine compounds can decompose in the ice clouds that occur in the cold Antarctic stratosphere, leading to the release of chemicals that are destructive to ozone.

"This was a truly beautiful piece of fundamental chemistry, and added significantly to his scientific achievements."


The scientific research by Drs. Crutzen, Molina, Rowland and others led to the 1987 United Nations' Montreal Protocol, which will ban the most dangerous CFCs from 1996 on. "Given compliance with the prohibitions, the ozone layer should gradually begin to heal after the turn of the century," the Academy said.

At his press conference, Professor Molina commented, "It's very rewarding to see how one can work with problems that affect society in a very direct way. Another rewarding aspect of the research is that we have seen how society responds to it. We not only made some doomsday scenarios that something bad might happen eventually, but we as a [scientific] community were actually able to convince society to do something about it."

As a result, "the problem of CFCs is to a very significant extent solved," Professor Molina said. "Society decided to ban the compounds, and it has done this in a clever way without doing away with all the benefits" such as spray cans and refrigeration. "It's just not essential to use these types of harmful compounds to get these benefits."


Being awarded a Nobel Prize "does feel like a vindication" of his work, said Professor Molina, who endured strong criticism when the research was published 21 years ago. He noted that at the time, environmental research "was not well accepted in the scientific community. Maybe it was thought that the issues were too complicated to understand well.

"But I think that over the years the scientific community involved in [these kinds of studies] has shown that one can do rigorous science, with scientific hypotheses that can be tested, and thankfully this leads to the acceptance of these types of ideas by the scientific community in general. So I see it as a prize for the entire community that is working with these issues."

The work is still criticized by some-two US Congressmen last month introduced legislation seeking to postpone the implementation of the ban on ozone-depleting chemicals. Asked to comment on that criticism, Dr. Molina replied: "In terms of the skeptics, there's only a very small group of scientists that disagree with what I believe is a pretty amazing international consensus. The science is really very clear, if you look at all the evidence. There is very little doubt that CFCs [are causing] ozone depletion in Antarctica."


Professor Molina was born in Mexico City. "From the very beginning as a high-school student I remember I was fascinated by science," he said at the press conference. But having such an interest "was not particularly easy, because the culture in Latin America is not one that praises science, particularly at that age. So I really had to struggle to keep my friends and keep at the same time my interest."

As a result, now that he is an established scientist, "I certainly try to encourage minority students to continue [in science]. We have too few scientists coming from, for example, Hispanic backgrounds, and it's clearly something that needs to be improved.

"So I always like to encourage them, and explain to them that they [must be] very patient, but in the end, it pays off. It can be very fun [and] very rewarding, as is the occasion today."

Professor Molina holds the chemical engineer degree (1965) from the Universidad Nacional Autonoma de Mexico, a postgraduate degree (1967) from the University of Freiburg, West Germany, and the PhD (1972) from the University of California, Berkeley.

He came to MIT in 1989 after holding teaching and research positions at the Universidad Nacional Autonoma de Mexico; the University of California, Berkeley; the University of California, Irvine, and the Jet Propulsion Laboratory at the California Institute of Technology.

Professor Molina is a member of the President's Council of Advisors on Science and Technology (PCAST). Now a naturalized American citizen, Dr. Molina is the first native scientist of Mexico to win a Nobel. (Mexican citizens won the Nobel Prize for literature in 1990 and the Nobel Peace Prize in 1982.)

Professor Molina's many awards include the Tyler Award in 1983, the Esselen Award of the American Chemical Society in 1987, and the Newcomb-Cleveland Prize of the American Association for the Advancement of Science for his 1987 paper in Science describing his work on Antarctic ozone hole chemistry. In 1989 he received the NASA Medal for Exceptional Scientific Achievement, and from 1990-92 he was a Pew Scholar on Conservation and the Environment.

Professor Molina's Nobel Prize brings to 28 the number of Nobel Prizes won by MIT faculty, alumni and staff since 1956. Current and emeritus members of the faculty have won the prize in medicine/physiology (4), physics (4), economics (3) and chemistry (1). Also, a staff doctor at MIT is a founder of the International Physicians for the Prevention of Nuclear War, which won the Nobel Peace Prize in 1985. A number of MIT faculty members have also been active in the Pugwash Conference which won this year's Nobel Peace Prize.

More information on The Nobel Prize can be found on the World Wide Web at this URL address: .

A version of this article appeared in MIT Tech Talk on October 18, 1995.

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