Mario Molina

José Mario Molina-Pasquel Henríquez was born on March 19, 1943, in Mexico City. His father, Roberto Molina Pasquel, was a lawyer who taught at the National Autonomous University of Mexico (UNAM) and later served as Mexico's ambassador to Ethiopia, Australia, and the Philippines. His mother, Leonor Henríquez, ran the household in a family that prized education ^[1].

Chemistry captured him early. As a boy he converted a bathroom in the family home into a small laboratory, working with toy chemistry sets and a microscope. An aunt, Esther Molina, was herself a chemist and guided his first serious experiments, going well beyond what school required ^[1]. At age eleven his parents sent him to a boarding school in Switzerland, the Institut auf dem Rosenberg, on the assumption that a future chemist needed German. He later recalled being disappointed that his European classmates showed no more interest in science than his friends back home ^[2].

He returned to Mexico and enrolled at UNAM, earning a degree in chemical engineering in 1965. The engineering program, he explained, was the practical route to advanced chemistry courses in Mexico at the time. He then spent nearly two years at the University of Freiburg in West Germany studying polymerization kinetics before deciding that his real interests lay in physical chemistry, a field that demanded stronger training in mathematics and physics ^[1].

In 1968 Molina entered the doctoral program at the University of California, Berkeley, joining the group of George C. Pimentel, a pioneer of chemical lasers. His thesis research used these lasers to study how energy distributes among the products of chemical reactions. Berkeley in those years was alive with debate over the social responsibility of science, an atmosphere Molina said shaped his conviction that research should serve society. He completed his Ph.D. in physical chemistry in 1972 ^[1].

The decisive move came in 1973, when he joined the laboratory of F. Sherwood Rowland at the University of California, Irvine, as a postdoctoral researcher. Offered a list of possible projects, Molina chose the one furthest from his previous experience: figuring out what happens to chlorofluorocarbons (CFCs), the inert industrial gases then used in aerosol sprays, refrigerators, and air conditioners, once they escape into the atmosphere ^[2].

Working through the chemistry, Molina and Rowland found that CFCs are so stable that nothing removes them in the lower atmosphere. Instead they drift upward over decades into the stratosphere, where harsh ultraviolet radiation finally breaks them apart, releasing chlorine atoms. Each chlorine atom, they calculated, could catalytically destroy thousands of molecules of ozone, the thin layer of gas that shields life on Earth from damaging ultraviolet light ^[3].

Molina and Rowland published their findings in the journal Nature on June 28, 1974, warning that continued CFC release threatened serious depletion of stratospheric ozone ^[3]. Any account of Mario Molina achievements begins with this paper. The two scientists did something then unusual: they went public, testifying before legislators and calling for a ban on CFC propellants. Industry pushed back hard, and some colleagues thought advocacy was improper for researchers, but Molina argued that scientists who understood a danger had a duty to explain it ^[2].

Vindication arrived in 1985, when British Antarctic Survey researchers reported a massive springtime loss of ozone over Antarctica, the phenomenon that became known as the ozone hole. Molina's subsequent laboratory work helped explain the unusual chlorine chemistry occurring on polar stratospheric cloud particles that made Antarctic depletion so severe ^[4]. The scientific case propelled diplomacy: the Montreal Protocol, signed in 1987 and eventually ratified by every United Nations member state, phased out CFC production worldwide. Atmospheric measurements have since shown the ozone layer slowly recovering ^[5].

In 1995 Molina shared the Nobel Prize in Chemistry with Rowland and the Dutch scientist Paul Crutzen for their work on atmospheric ozone. He was the first Mexican-born scientist to win a science Nobel ^[6]. Other honors followed across his career, including the Tyler Prize for Environmental Achievement in 1983, election to the U.S. National Academy of Sciences, and the Presidential Medal of Freedom, awarded by Barack Obama in 2013 ^[7].

Molina married Luisa Tan, a fellow chemist he met at Berkeley, in July 1973. She became a close scientific collaborator, co-authoring research on atmospheric chemistry, and the couple had one son, Felipe, who became a physician. The marriage ended in divorce in 2005 ^[1].

In 2006 he married Guadalupe Álvarez, and in his later years he divided his time between the United States and Mexico City. Colleagues and students consistently described him as modest and patient, a scientist who preferred careful explanation to confrontation even when facing hostile questioning from industry representatives in the 1970s ^[2].

He held dual Mexican and American citizenship and moved comfortably between the two countries' scientific communities, mentoring generations of students on both sides of the border ^[7].

After Irvine, Molina worked at the Jet Propulsion Laboratory in Pasadena from 1982 to 1989, then joined the Massachusetts Institute of Technology, where he held a joint appointment in the Department of Earth, Atmospheric and Planetary Sciences and the Department of Chemistry ^[1]. At MIT he broadened his focus from the stratosphere to the polluted air of megacities, leading a major collaborative study of air quality in the Mexico City metropolitan area with Luisa Molina ^[8].

In 2004 he moved to the University of California, San Diego, and in 2005 he founded the Centro Mario Molina for Strategic Studies on Energy and the Environment in Mexico City, a research center dedicated to practical solutions on energy, air quality, and climate policy in Mexico and Latin America ^[7].

He served as a science advisor to Mexican presidents and sat on the U.S. President's Council of Advisors on Science and Technology under Barack Obama. In his final years he campaigned for aggressive action on climate change, arguing that the Montreal Protocol proved nations could act together on atmospheric threats when the science was clear. During the coronavirus pandemic of 2020 he co-authored a widely discussed study on the airborne transmission of the virus and the value of face masks. He died of a heart attack in Mexico City on October 7, 2020, at age 77 ^[9].

Anyone asking who was Mario Molina finds a rare figure: a researcher whose calculations directly changed international law. The Montreal Protocol is routinely cited as the most effective environmental agreement in history, and scientific assessments project that the ozone layer will return to its 1980 condition around the middle of this century, sparing millions of people from skin cancers and cataracts ^[5].

In Mexico he remains a national icon. The Centro Mario Molina continues to shape energy and climate policy, universities and schools carry his name, and on March 19, 2023, Google marked his 80th birthday with a commemorative Doodle seen around the world ^[7]. Any Mario Molina biography also records his influence as a role model: he spoke often about growing up in Mexico City and insisted that world-class science could emerge from anywhere.

His larger lesson concerned the relationship between knowledge and action. Molina showed that scientists could sound an alarm responsibly, defend their findings against powerful commercial interests, and help design workable solutions. That template, forged in the ozone fight of the 1970s and 1980s, now guides much of the global response to climate change ^[9].