Mario Molina

Mario Molina
Born	Mario José Molina Henríquez 19 3, 1943
Birthplace	Mexico City, Mexico
Died	Template:Death date and age Mexico City, Mexico
Nationality	Mexican
Occupation	Physical chemist, academic
Employer	Massachusetts Institute of Technology, University of California San Diego
Known for	Discovery of CFC-driven ozone depletion, co-recipient of 1995 Nobel Prize in Chemistry
Education	University of California, Berkeley (PhD)
Awards	Nobel Prize in Chemistry (1995), Presidential Medal of Freedom (2013), Tyler Prize for Environmental Achievement (1983)

Mario José Molina-Pasquel Henríquez (19 March 1943 – 7 October 2020) was a Mexican physical chemist whose research fundamentally altered the scientific understanding of Earth's atmosphere and led to one of the most consequential environmental treaties in history. In 1974, together with his postdoctoral advisor F. Sherwood Rowland, Molina published a landmark paper demonstrating that chlorofluorocarbon (CFC) gases—then widely used in refrigerants, aerosol sprays, and industrial solvents—could migrate to the stratosphere and catalytically destroy ozone molecules, thinning the protective ozone layer that shields the planet from harmful ultraviolet radiation. This discovery, initially met with skepticism and fierce opposition from the chemical industry, was dramatically confirmed by the observation of the Antarctic ozone hole in 1985 and led directly to the adoption of the Montreal Protocol in 1987. For this work, Molina shared the 1995 Nobel Prize in Chemistry with Rowland and Paul J. Crutzen, becoming the first Mexican-born scientist to receive a Nobel Prize in Chemistry and only the third Mexican-born Nobel laureate overall. Over a career spanning more than five decades, Molina held positions at the University of California, Irvine; the California Institute of Technology; the Massachusetts Institute of Technology; and the University of California, San Diego, and he remained an influential voice in climate and environmental policy until his death in 2020.

Early Life

Mario José Molina Henríquez was born on 19 March 1943 in Mexico City, Mexico. He grew up in a professional family; his father, Roberto Molina Pasquel, was a lawyer and diplomat who at one point served as Mexico's ambassador to Ethiopia, Australia, and the Philippines. From an early age, Molina displayed a deep curiosity about the natural world. He became fascinated by chemistry as a child, reportedly converting a bathroom in his family's home into a makeshift laboratory where he conducted experiments with toy microscopes and chemistry sets. This early enthusiasm was encouraged by an aunt who was herself a chemist and who introduced him to more advanced scientific concepts beyond what his school curriculum offered.

Molina's early education took place in Mexico City. As a young boy, he was already determined to become a research chemist. His family's international connections meant that he spent part of his youth abroad; as a child, he attended school in Switzerland, where he improved his German language skills—a preparation that would later prove useful when he pursued graduate studies in Europe. Despite the opportunities afforded by his family's social position, Molina later recalled that pursuing a career in basic scientific research was an unusual choice in 1960s Mexico, where professional careers in law, medicine, or engineering were more commonly expected of young men from his background.

Education

Molina began his undergraduate studies at the National Autonomous University of Mexico (UNAM), where he earned a bachelor's degree in chemical engineering. Seeking further academic training, he then traveled to Europe and enrolled at the University of Freiburg in Germany, where he obtained a postgraduate degree (Diplomchemiker, equivalent to a master's degree) and deepened his knowledge of polymerization kinetics.

Molina subsequently moved to the United States to pursue doctoral studies at the University of California, Berkeley. There, he worked under the supervision of George C. Pimentel, a distinguished physical chemist known for his work on chemical lasers and molecular spectroscopy. Molina completed his PhD in 1972 with a dissertation titled Vibrational Populations Through Chemical Laser Studies: Theoretical and Experimental Extensions of the Equal-gain Technique. His doctoral research focused on the chemical dynamics of laser-induced molecular processes, providing him with a rigorous foundation in physical chemistry and spectroscopy that would prove essential to his later atmospheric research. The training under Pimentel, who was known for encouraging students to tackle problems of broad scientific and societal significance, had a lasting influence on Molina's approach to research.

Career

Early Research and the CFC-Ozone Discovery

After completing his doctorate at Berkeley in 1972, Molina joined the research group of F. Sherwood Rowland at the University of California, Irvine, as a postdoctoral fellow. Rowland had become interested in the atmospheric fate of chlorofluorocarbons—synthetic chemical compounds that had been manufactured in large quantities since the 1930s for use as refrigerants, propellants in aerosol cans, foam-blowing agents, and industrial solvents. CFCs were valued precisely because they were chemically inert and nontoxic at ground level, and it was assumed that they posed no environmental hazard. Rowland offered Molina the opportunity to investigate what ultimately happened to these compounds once released into the atmosphere.

Molina's research quickly yielded alarming results. He and Rowland determined that CFCs, while stable in the lower atmosphere, would gradually drift upward into the stratosphere, where they would be broken apart by intense ultraviolet radiation. This photodissociation would release free chlorine atoms, which could then engage in a catalytic cycle of ozone destruction—each chlorine atom capable of destroying tens of thousands of ozone molecules before being deactivated. The implications were profound: industrial CFC emissions, which had been growing rapidly for decades, posed a direct threat to the stratospheric ozone layer, the thin gaseous shield that absorbs most of the sun's biologically damaging ultraviolet-B radiation.

In June 1974, Molina and Rowland published their findings in the journal Nature in a paper that would become one of the most consequential scientific publications of the twentieth century. The paper predicted that if CFC production continued at existing rates, the ozone layer would suffer significant depletion over the coming decades, with potentially catastrophic consequences for human health—including increased rates of skin cancer and cataracts—and for ecosystems worldwide.

Opposition and Vindication

The Molina-Rowland hypothesis provoked an immediate and intense reaction. The chemical industry, led by CFC manufacturers such as DuPont, initially dismissed the findings and mounted a public relations campaign to discredit the science. Molina and Rowland faced personal attacks and professional skepticism; some industry representatives characterized their work as speculative and alarmist. Despite this opposition, Molina and Rowland persisted in presenting their findings to scientific audiences, government agencies, and the public. Their work prompted the United States to ban CFCs in aerosol spray cans in 1978, though broader industrial uses continued largely unchecked.

The scientific case was dramatically strengthened in 1985 when a team of British Antarctic Survey scientists led by Joseph Farman reported the discovery of a severe and unexpected thinning of the ozone layer over Antarctica—the so-called "ozone hole." This discovery confirmed the core predictions of the Molina-Rowland hypothesis and galvanized international action. Molina himself contributed to the scientific understanding of the ozone hole by elucidating the chemical mechanisms occurring on the surfaces of polar stratospheric ice clouds, which greatly accelerated chlorine-driven ozone destruction in the extreme cold of the Antarctic stratosphere. This work on heterogeneous chemistry—chemical reactions occurring on solid or liquid surfaces rather than in the gas phase alone—was a significant extension of the original theory and helped explain why ozone depletion was so severe over the poles.

The growing body of scientific evidence led to the negotiation and signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987, an international treaty that phased out the production and consumption of CFCs and other ozone-depleting substances. The Montreal Protocol has been ratified by every member of the United Nations and is often cited as the most successful international environmental agreement in history. Scientists have estimated that, as a result of the treaty, the ozone layer is expected to recover to its pre-1980 levels by the middle of the twenty-first century.

Academic Positions

Throughout his career, Molina held positions at several of the world's leading research universities. After his postdoctoral work at UC Irvine, he joined the Jet Propulsion Laboratory at the California Institute of Technology, where he continued his atmospheric chemistry research. In 1989, he moved to the Massachusetts Institute of Technology, where he was appointed professor in the Department of Earth, Atmospheric and Planetary Sciences and the Department of Chemistry. At MIT, Molina held the prestigious title of Institute Professor—the highest academic honor bestowed on a faculty member at the institution, reserved for individuals of exceptional distinction who have made contributions of special significance.

At MIT, Molina expanded his research interests beyond ozone chemistry to encompass broader questions of air quality, urban pollution, and climate change. He studied the atmospheric chemistry of very large cities, particularly Mexico City, examining the complex photochemical processes that produce smog and the health effects of air pollution on urban populations. This research was especially relevant to developing nations experiencing rapid urbanization and industrialization.

In 2004, Molina left MIT and moved to the University of California, San Diego, where he held a position at the Department of Chemistry and Biochemistry and was affiliated with the Center for Atmospheric Sciences at the Scripps Institution of Oceanography. He maintained the title of Institute Professor Emeritus at MIT for the remainder of his life.

The Mario Molina Center and Policy Work

In addition to his academic appointments in the United States, Molina founded the Centro Mario Molina para Estudios Estratégicos sobre Energía y Medio Ambiente (Mario Molina Center for Strategic Studies on Energy and the Environment) in Mexico City. The center conducted research and provided policy guidance on energy, climate change, air quality, and sustainable development in Mexico and Latin America.

Molina served as a climate policy advisor to Mexican President Enrique Peña Nieto and was an influential voice in Mexico's environmental governance. He was an early and vocal advocate for action on climate change, arguing that the success of the Montreal Protocol demonstrated that the international community could effectively address global environmental threats through science-based policy. He also advocated for amending the Montreal Protocol to phase down hydrofluorocarbons (HFCs)—chemicals that had been introduced as CFC replacements but were themselves potent greenhouse gases. This advocacy contributed to the adoption of the Kigali Amendment to the Montreal Protocol in 2016, which established a global schedule for reducing HFC production and consumption.

Molina served on numerous advisory boards and committees, including the President's Council of Advisors on Science and Technology (PCAST) in the United States under President Barack Obama. He also served on the board of the MacArthur Foundation and on the Pontifical Academy of Sciences at the Vatican. Throughout his later career, Molina was a consistent public advocate for the integration of scientific evidence into environmental and energy policy at both national and international levels.

Personal Life

Molina was married twice. His first wife, Luisa Y. Tan, was a fellow chemist whom he met during his graduate studies; they had a son, Felipe. The couple later divorced. Molina subsequently married Guadalupe Álvarez, who shared his interest in environmental issues and collaborated with him on policy initiatives through the Mario Molina Center.

Molina was known among colleagues for his quiet determination, intellectual rigor, and commitment to public service. Despite the recognition he received, he maintained a modest personal demeanor and frequently expressed his belief that scientists had a responsibility to communicate their findings to the public and to policymakers, particularly on matters affecting public health and the environment.

Mario Molina died on 7 October 2020 in Mexico City at the age of 77. His death was widely mourned in the scientific community, in Mexico, and internationally. Tributes came from heads of state, scientific organizations, and environmental groups around the world, acknowledging his contributions to atmospheric science and to the protection of the global environment.

Recognition

Molina received numerous awards and honors throughout his career. The most prominent was the 1995 Nobel Prize in Chemistry, which he shared with F. Sherwood Rowland and Paul J. Crutzen "for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone." He was the first Mexican-born scientist to receive a Nobel Prize in Chemistry and the third Mexican-born person to receive a Nobel Prize of any kind.

In 2013, Molina was awarded the Presidential Medal of Freedom by President Barack Obama, the highest civilian honor in the United States. He also received the Tyler Prize for Environmental Achievement (1983), one of the most prestigious awards for environmental science, as well as the NASA Medal for Exceptional Scientific Achievement and the United Nations Environment Programme (UNEP) Sasakawa Environment Prize.

Molina received the Willard Gibbs Award from the American Chemical Society's Chicago Section. He was also the recipient of numerous honorary degrees from institutions around the world, including Duke University, Harvard University, Yale University, Tufts University, and several Mexican universities including the Universidad Autónoma del Estado de Hidalgo and the Universidad Autónoma del Estado de México.

The minor planet 9680 Molina, discovered in 1975, was named in his honor.

Legacy

Mario Molina's scientific contributions had far-reaching consequences for environmental protection on a global scale. His 1974 paper with Rowland is credited with initiating the chain of scientific and political developments that led to the Montreal Protocol, which has been described by former United Nations Secretary-General Kofi Annan as "perhaps the single most successful international agreement to date." The protocol's success in averting catastrophic ozone depletion has been estimated to have prevented millions of cases of skin cancer and cataracts worldwide and to have averted significant damage to agricultural productivity and marine ecosystems.

Beyond the ozone issue, Molina's career demonstrated the capacity of fundamental scientific research to inform and shape public policy. His work on the Montreal Protocol became a model for subsequent efforts to address global environmental challenges, including climate change. Molina himself frequently drew parallels between the CFC-ozone problem and the challenge of greenhouse gas emissions, arguing that the scientific evidence for anthropogenic climate change was compelling and that political action was both necessary and achievable.

Molina's legacy also extends to his role as an inspiration for scientists in Latin America and in the broader Hispanic community. As the first Mexican-born Nobel laureate in Chemistry, he became a symbol of scientific excellence and a role model for aspiring researchers in the developing world. The Mario Molina Center in Mexico City continues to carry forward his work on energy and environmental policy, focusing on issues such as air quality, climate mitigation, and sustainable urban development.

In the field of atmospheric chemistry, Molina's work on heterogeneous chemical reactions on polar stratospheric clouds opened new avenues of research that continue to be explored by scientists seeking to understand the complex interplay of chemistry, physics, and meteorology in the atmosphere. His insistence on rigorous science, combined with a willingness to engage with policymakers and the public, set a standard for the role of scientists in addressing environmental crises that remains influential in the scientific community.