Mario Molina (1943-2020), Mexico and USA

Nobel Prize in Chemistry in 1995 for “work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone.”

Mario Jose Molina Pasquel Henriquez was bon on March 19, 1942, in Mexico City. His father, Roberto Molina Pasquel, was an attorney and part-time professor at the Universidad Nacional Autónoma de México (Autonomous National University of Mexico — UNAM), where he created an institute for international law. Mario’s mother, Leonor Henriquez, died when Mario was only three years old. His father later married Luz Lara, a former elementary school teacher, who was like a mother to Mario and his older brother and sisters.

At a young age, Mario enjoyed classical music and took violin lessons. After getting a microscope for his 8th birthday, however, his interests expanded to include science. He set out some lettuce until it began to rot, then used the microscope to look at a drop of water from the rotten lettuce and saw microscopic organisms. His aunt Esther Molina, herself a chemist, helped him set up an informal chemistry laboratory in his home, contributing equipment and supplies beyond what was found in a child’s chemistry set. She also helped him conduct chemistry experiments at a level quite advanced for an elementary school student.

In his family, it was a tradition to send children abroad to study after they completed elementary school. Mario’s older sisters had gone to Canada while his brother had studied in Massachusetts. Because it was thought that it would be beneficial for a budding scientist to learn German, in 1954, 11-year-old Mario was sent to study at the Institute auf dem Rosenberg in St. Gallen, Switzerland. Although the other students there did not seem to share his passion for science, he got along well with his chemistry and math teachers. He learned to speak Italian as well as German to be able to communicate with his classmates, as none spoke Spanish but many spoke Italian.

In 1960, Mario returned to Mexico and enrolled at UNAM. At that time in Mexico, students had to focus on either the sciences or humanities with little chance to change majors. Mario chose to pursue chemical engineering, as it had a mathematical, problem-solving orientation.

For graduation, the 5-year bachelor’s program required a thesis that would focus on a topic with a commercial application, such as a connection between chemistry and business or something that could be manufactured. Molina and some college friends looked at methods to produce a catalyst used to produce polyurethane foam. Because of Mexican trade law, products made in Mexico were favored over imported products. The ammonia-based catalyst at that time was imported, so Molina and his friends conducted inexpensive, small scale experiments to determine the organic chemicals and metals, such as tin and hydrochloric acid, that would be needed to make the catalyst. Once they had this solved, through connections they obtained a loan to get the equipment needed to scale up their small experiments to industrial production, thus creating a domestic source for the catalyst.

Molina was awarded his Bachelor’s in Science degree from UNAM in 1965. As his degree was in chemical engineering, he felt a need to focus more on the academic and research side of chemistry, which would require more coursework in physics and mathematics. Molina worked at UNAM after graduation, helping establish a Master’s program in chemical engineering, until he received a scholarship to study polymer chemistry at the University of Freiburg in Germany. As part of his undergraduate studies, Molina had studied chemical kinetics from the perspective of the rates of reactions, yet now for his Master’s program he wanted to look more at how and how fast molecules change during chemical reactions. This required a greater understanding of quantum mechanics at the molecular level. After two years of studying polymerization kinetics, he received his degree from the University of Freiburg in 1967.

At this point, Molina decided that he wanted to get a Ph.D. in the United States. Unlike in Mexico and Germany, where the teaching style is for the professor to lecture and the students to take notes, professors at the doctoral level in the United States acted more as mentors conversing with students. Part of the application process was to prove proficiency in German, which involved translating a text from German to English. For Molina, it was easier to read and understand the German than it was to write in English.

To get a scholarship to pursue a doctoral program at Berkeley, Molina had to apply a year in advance. While waiting to be accepted into the program, he studied mathematics at the Sorbonne in Paris, France. The year in Paris, during a time of cultural unrest, allowed Molina to learn about issues outside of chemistry, as his friends were in different fields. This reinforced his belief that, as a scientist, it is important to not be single-minded but to interact with multiple areas of interest. For instance, he reconnected with his childhood love of music and learned to play classical guitar.

Once he was accepted into the doctoral program at the University of California (UC) at Berkeley in 1968, Molina found early on that his ability to read scientific literature in English did not make it easy to communicate with teachers and classmates in English. The doctoral program in physical chemistry involved a lot of interaction in small classes for difficult courses that demanded a lot of time and effort in homework and original research. Molina joined a research group led by Dr. George Pimental, who became a mentor to Molina. The research focused on the nature of chemical reactions using chemical lasers, which were new at the time. Molina’s work also required him to write scientific articles about this research, using a stylized form of writing common to scientists but not to the public in general. This helped Molina become prepared to write his doctoral thesis, on the energy changes in molecules that take place during chemical and photochemical (induced by light) reactions. He was awarded his PhD in 1972 and continued in a postdoctoral position for a year at Berkeley.

In July 1973, Molina married Luisa Tan, who had been one of the few female students to study with Dr. Pimentel. As a fellow chemist, his wife assisted him with his research and also conducted her own research with other research groups, including on low temperature spectroscopy. In 1975, Molina became a US citizen. In 1977, their son Felipe José was born. (He later became a physician in Boston.)

In the fall of 1973, Molina moved to UC Irvine for a second postdoctoral position, under the supervision of F. Sherwood Rowland, known as Sherry to his friends. Molina and Rowland began to study the behavior of chlorofluorocarbons (CFCs) in the upper atmosphere. At lower levels, CFCs are stable, so most scientists assumed they would have little impact on the environment. Molina and Rowland wondered if the greater amount of solar radiation higher in the atmosphere, such as in the stratosphere, would be able to break apart the molecules of CFCs. Using computer modeling and a variety of experimental methods, including spectroscopy, they conducted research into their hypothesis, that in the presence of solar radiation in the stratosphere, CFCs would break apart or decompose into several chemicals, including chorine atoms. Chlorine can act as a catalyst in the decomposition of ozone (O₃) into oxygen (O₂) in such a way that only small amounts of chlorine can break apart thousands of molecules of ozone, having a great impact on the ozone layer. It is the ozone layer that acts as a barrier to solar radiation so that not too much reaches the lower levels of the atmosphere and the surface of the earth. Their research also showed that, in the stratosphere, chemical reactions could speed up at lower temperatures, even though closer to earth they speed up at higher temperatures and slow down at cooler ones.

When Molina and Rowland published the results of their research in the scientific magazine Nature in 1974, there was no firm evidence that the ozone layer was being damaged. While they knew that amassing enough data to provide that evidence could take 10 years, they also know that, if they were right, they needed to warn people about the potential danger, not just fellow scientists but also the general public and policymakers. To reach this new audience, they had to adjust how they communicated with the news media so the implications of their findings could be better understood. At this time, the environmental movement was just starting, but it focused on local water and air pollution, not something as global as the ozone layer. As more people in the scientific community began to take the issue seriously, Molina and Rowland testified at hearings with lawmakers at the state and national levels about the establishment of environmental regulations on CFCs. Some of the chemical companies that produced CFCs started to look for possible replacements in case CFCs, which were used in aerosol cans and refrigerants, were proven to be harmful.

By the 1980s, there were three types of scientists working on the ozone problem: computer modelers, laboratory scientists like Molina, and those who conducted measurements in the environment. Several methods had been devised to measure the level of ozone in the stratosphere. One method used measurements of how much ultraviolet light reaches the ground, as only ozone can absorb ultraviolet light. Another method used data gathered by satellites, while a third method used high altitude planes over Antarctica to gather air samples. The three methods all showed that there was a spot over Antarctica (the ozone hole) that had no ozone but high levels of chlorine. These data supported Molina and Rowland’s hypothesis that CFCs could damage the ozone layer.

Molina and other laboratory scientists used spectroscopic techniques that measure particular wavelengths of light to identify specific chemicals, as chemicals like chlorine absorb particular wavelengths of light. In addition, they used flash photolysis to follow the changes in the amounts of chemicals. Molina and Rowland developed their own instrumentation or adapted already existing instruments (like mass spectrometers and lasers), designing instruments that other specialists, like machinists or glass blowers, would actually make. By conducting experiments to analyze the behavior of chlorine, Molina and Rowland determined that chlorine peroxide was a key factor in the development of the ozone hole over Antarctica.

The reports that Molina and Rowland wrote provided a basis for negotiations the resulted in the Montreal Protocol, finalized in 1987. The Montreal Protocol was the first international agreement to create a consensus among nations on actions to take to confront an environmental condition on a global scale. This created a precedent for future international action on such issues as global climate change, addressed by the International Panel on Climate Change (IPCC). Mexico was the first nation to ratify the Montreal Protocol.

While this research and environmental efforts were going on, Molina had a few career changes. Molina began working with Rowland as a postdoctoral fellow at UC Irvine in 1973. In 1975, he was appointed as a faculty member there, setting up an independent program to study chemicals and spectroscopic properties of compounds that affect the atmosphere, including those that contain chlorine atoms in some form. As a faculty member, Molina had to deal with students, which limited the time he could devote to experiments. In 1982, he decided to take a non-teaching position at the Molecular Physics and Chemistry section of the Jet Propulsion Laboratory (JPL), in Pasadena, where he directed only a few postdoctoral fellows. After it was shown that there is seasonal depletion of ozone over Antarctica, Molina and his group at JPL looked more closely at the effect of polar stratospheric clouds that can have ice crystals. In the lab, Molina simulated the chemical effects of clouds over Antarctica and showed that chlorine-activation reactions take place in the presence of ice under polar stratospheric conditions.

Wanting to return to teaching, in 1989 Molina took a position at the Massachusetts Institute of Technology (MIT), where he also continued his research on global atmospheric chemistry issues. In 1994, Molina served as a member of the US President’s Committee of Advisors on Science and Technology (PCAST) under President Clinton, then again under President Obama. Molina also was on the Board of Directors of the Union of Concerned Scientists.

In 1995, Molina, along with Rowland and Paul Crutzen of the Netherlands, was awarded the Nobel Prize in Chemistry for their “work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone.” This was the first time a Nobel Prize was given for research on environmental degradation resulting from human-made substances. Molina felt that the fame he achieved from winning the Nobel Prize carried with it the responsibility to educate the public about other human-made chemical pollutants. In 1996, he donated two-thirds of his Nobel Prize money to MIT to establish a fellowship program to help students from less developed nations conduct research in atmospheric sciences.

Around this time, Molina turned his attention to atmospheric chemistry at lower levels of the atmosphere, close to earth, especially air pollution in Mexico City. He wanted his students at MIT to be exposed to multidisciplinary approaches to societal problems and relate policy. To that end, he helped establish the Integrated Program on Urban, REgional and Global Air Pollution at MIT. He also initiated research projects that involved multidisciplinary scientists from both the United States and Mexico and collaborated with policymakers to find and implement ways to improve air quality in Mexico City. He saw that urban air pollution is linked with climate change, as chemical compounds like black carbon (soot) and methane are important factors in both urban air quality and climate change. In 2002, Molina and his wife Luisa published their work Air Quality in the Mexico Megacity and presented it to a group of scientists and government officials in Mexico City.

In 2004-2005, Molina founded the Centro Mario Molina para Estudios Estratégicos sobre Energia y Medio Ambiente (www.centromariomolina.org; the Mario Molina Center for Strategic Studies in Energy and the Environment) in Mexico City to focus on practical solutions between science and public policy on energy and environmental matters to promote sustainable development and vigorous economic growth.

As Molina wanted to spend more time in Mexico City but MIT did not want professors to be part-time, Molina accepted a position at UC San Diego and the Scripps Institution of Oceanography in 2004. He and his first wife Luisa divorced in 2005, and in 2006 Mario Molina married his second wife, Guadalupe Alvarez. On October 8, 2020, Molina died of a heart attack at his home in Mexico City.

References:

“Mario J. Molina — Facts” and “Mario J. Molina — Biographical” at http://www.NobelPrize.org

Newton, David E (2007). “Molina, Mario” in Latinos in Science, Math and Professions. Facts on File, NY.

“Mario Molina” at http://www.Sciencehistory.org

Caruso, David J. and Roberts, Jody A. “Oral History Interview with Mario Molina May 6-7, 2013 at digital.sciencehistory.org/works/8pmnklq?

“Mario Molina” at en.wikipedia.org

“Mario J. Molina, PhD” at http://www.achievement.org/achiever/mario-j-molina-ph-d/

“Mario Molina” at http://www.britannica.com

“National Hispanic Heritage Month: Mario J. Molina” at http://www.planetaid.org

“Hispanic Heritage Month Profile: Mario J. Molina” at mbb.yale.edu

“5 Scientists in Latino History who Changed the World” at http://www.tylerprize.org