Mario Molina

• Born: March 19, 1943
• Birthplace: Mexico City, Mexico
• Died: October 7, 2020
• Place of death: Mexico City, Mexico

Mexican-born scientist

Molina’s work in atmospheric science, particularly in explaining the deleterious effect of chlorofluorocarbons on the ozone layer, earned him a share of the 1995 Nobel Prize in Chemistry. It vindicated environmental science, which previously had been belittled by mainstream science.

Early Life

José Mario Molina-Pasquel Henríquez was born in Mexico City, Mexico, to Roberto Molina-Pasquel and Leonor Henríquez de Molina. His father was a lawyer who taught at Mexico City’s Universidad Nacional Autónoma de Mexico (UNAM) and later was the Mexican ambassador to Ethiopa, Australia, and the Philippines. Inspired by his aunt, chemist Esther Molina, young Molina performed experiments in a home laboratory. After attending elementary and high school in Mexico City, at age eleven he attended a boarding school in Switzerland.

In 1960, Molina entered the chemical engineering program at UNAM, where he took mathematics-oriented courses not open to chemistry majors and earned his BS degree in 1965. He spent two years working on polymerization kinetics at the University of Freiburg, Germany, where he earned a master’s degree in 1967. Returning to UNAM as an assistant professor, he established the first graduate program in chemical engineering.

In 1968, Molina joined George C. Pimentel’s research group at the University of California at Berkeley. He studied the distribution of internal energy in the products of chemical and photochemical reactions using lasers and other instruments. During his years in Berkeley, near the end of the free-speech movement, he realized the impact of science and technology on society and began his lifelong opposition to the application of research for weapons and other potentially destructive purposes. Molina earned his PhD in 1972 and continued his research on chemical dynamics at Berkeley for another year. On July 12, 1973, he married fellow graduate student Luisa Y. Tan, with whom he collaborated on environmental and other scientific topics.

In 1973, Molina joined Professor F. Sherwood Rowland at the University of California at Irvine as a postdoctoral fellow. He studied the accumulation in the atmosphere of inert chlorofluorocarbons (CFCs), then thought to have no effect on the environment. At Irvine, where he was an assistant professor and associate professor from 1975 to 1982, he studied the chemical and spectroscopic properties of unstable atmospherically important compounds.

Life’s Work

CFCs—nontoxic, nonflammable, inexpensive compounds widely used in industrial products such as refrigerants, aerosol propellants, and solvents—can persist in the atmosphere for forty to fifty years because of their inertness. In 1970, James E. Lovelock showed that these gases had spread throughout the atmosphere; the next year, he found that a CFC, trichlorofluororomethane, had spread through the troposphere (the lowest layer of the atmosphere) over the north and south Atlantic Ocean. Molina and Rowland began their search for a “sink”—the reactions by which CFCs are decomposed and where this decomposition occurs. The process through which these particles decompose yields chlorine atoms, which break down ozone molecules and deplete the ozone layer that protects the Earth from the sun’s harmful ultraviolent rays.

Molina and Rowland calculated by reaction rate measurements that continued use of CFCs for several decades would deplete the ozone layer by several percent. A 5 percent depletion would produce an additional forty thousand cases of skin cancer in the United States after 2050. CFCs also contribute to the greenhouse effect and global climate change. In the June 28, 1974, issue of Nature, Molina and Rowland warned of the deleterious effects of CFCs on the atmosphere. Their article initially was ignored by the academic community, so they reported their results on September 11, 1974, at the American Chemical Society’s national meeting in Atlantic City, New Jersey, where they held a press conference. Their subsequent appearances before legislative committees urging a complete ban on CFCs garnered them extensive coverage in the popular press and alerted the public to the danger. Despite opposition of anti-environmentalists and commercial manufacturers, a consensus emerged that industrially manufactured gases were responsible for destroying the ozone layer. The US Environmental Protection Agency (EPA) banned the use of CFCs in aerosols in 1978, and some companies developed nonchlorine-containing products as refrigerants and aerosol sprays. The 1987 Montreal Protocol and subsequent provisions restricted atmospheric release of manufactured ozone-destroying gases.

Molina worked in the Molecular Physics and Chemical Section at the National Aeronautics and Space Administration’s Jet Propulsion Laboratory in Pasadena, California, from 1982 to 1989. After learning of Joseph Farman’s discovery of the seasonal depletion of ozone over Antarctica, Molina showed that this effect could be attributed to chlorine-activation reactions under polar stratospheric conditions. Molina, Rowland, and the Dutch-born Paul J. Crutzen received the 1995 Nobel Prize in Chemistry for their work in atmospheric chemistry, particularly in the area of ozone depletion, an award widely regarded as a vindication of environmental and atmospheric science.

Molina was professor of chemistry and atmospheric chemistry from 1989 to 1997 and institute professor of earth, atmosphere, and planetary sciences from 1997 to 2004 at the Massachusetts Institute of Technology (MIT). He was elected to the US National Academy of Sciences in 1993 and the US Institute of Medicine in 1996. On July 1, 2004, he assumed joint appointments with the Department of Chemistry and Biochemistry at the University of California at San Diego and the Center for Atmospheric Sciences at the Scripps Institution of Oceanography in La Jolla, California. In 2005, he founded a center for strategic studies in energy and environment in Mexico City. Molina held a number of honorary degrees and served on the President’s Council of Advisors in Science and Technology, the Secretary of Energy Advisory Board, National Research Council Board on Environmental Studies and Toxicology, and the boards of the US-Mexico Foundation for Science and other nonprofit environmental organizations. An asteroid was named in his honor. After his divorce from Luisa, in February, 2006, Molina married Guadalupe Álvarez.

Remaining active in the discussions regarding climate change, Molina provided testimony during a hearing held by the House Select Committee on Energy Independence and Global Warming in 2010. Three years later, he was recognized further for his work when he was given the Presidential Medal of Freedom by President Barack Obama. In later years, he took part in scientific investigations of the role of face masks during the coronavirus disease 2019 (COVID-19) pandemic.

After suffering a heart attack, Molina died at his home in Mexico City on October 7, 2020, at the age of seventy-seven.

Significance

Molina was the first Mexican-born citizen to receive a Nobel Prize in Chemistry. His work brought atmospheric chemistry into the mainstream by demonstrating that human activities can adversely affect the Earth’s fragile environment. He donated $200,000 of the prize money to fund a fellowship program to provide advanced training at MIT for young environmental researchers from developing countries. In the PBS television program Breakthrough: The Changing Face of Science in America (1996), he was one of twenty African American, Latino, and American Indian scientists who discussed their research and careers. Molina collaborated with colleagues from many disciplines on the chemistry of atmospheric pollution and issues of global climate change, especially in rapidly growing cities, in addition to serving as an advisor for the federal government. He also significantly improved the air quality of Mexico City.

Bibliography

Cullen, Katherine. “Mario J. Molina.” In Weather and Climate: The People Behind the Science. New York: Facts On File, 2006. Describes Molina’s career and impact on the environmental movement and the field of atmospheric science. Aimed at younger readers.

Kauffman, George B., and Laurie M. Kauffman. “Atmospheric Chemistry Comes of Age.” Today’s Chemist at Work 5, no. 10 (November, 1996): 52-58. An account of the award of the 1995 Nobel Prize in Chemistry to Crutzen, Molina, and Rowland and details of their lives and work.

Molina, Mario J. “Polar Ozone Depletion.” In Nobel Lectures Including Presentation Speeches and Laureates’ Biographies: Chemistry, 1991-1995, edited by Bo G. Malmström. River Edge, N.J.: World Scientific Publishing Company, 1997. Nobel lecture account of Molina and Rowland’s research and results. Molina’s portrait and autobiography also are included.

Molina, Mario J., and F. Sherwood Rowland. “Stratospheric Sink for Chlorofluoromethanes: Chlorine-Atom Catalysed Destruction of Ozone.” Nature 249 (June 28, 1974): 810-814. This frequently cited paper described what many have called a “planetary time bomb” and “invisible menace.”

Schwartz, John. "Mario Molina, 77, Dies; Sounded an Alarm on the Ozone Layer." The New York Times, 13 Oct. 2021, www.nytimes.com/2020/10/13/science/mario-molina-dead.html. Accessed 9 Apr. 2021.