Mario José Molina is a Mexican-born American chemist who was jointly awarded the 1995 chemistry prize, along with F. Sherwood Rowland (US) and Paul J. Crutzen (Netherlands), “for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone.” Most people are aware of the threat to the ozone layer, which shields the Earth from solar radiation, but it was as early as the 1970s that Molina and Rowland first highlighted the problem. Their work led to an international movement to cut the use of chlorofluorocarbon (CFC) gases.
Molina was born in Mexico City in 1943. His father was a lawyer and lecturer who later became an ambassador. Mario attended school in Mexico City and Switzerland and developed an early interest in chemistry, helped by his aunt, who was a chemist. In 1960, he entered the Universidad Nacional Autonoma de Mexico, studying chemical engineering and gained a BSc in 1965 before going on to earn a postgraduate degree from the University of Freiburg, West Germany in 1967. After a time studying in Paris, he returned to Mexico as an assistant professor at UNAM and set up a graduate program in chemical engineering.
In 1968 he left for the US, gaining his PhD in physical chemistry at the University of California, Berkeley in 1972. He stayed on for a year at Berkeley before joining Rowland’s group at the UC Irvine as a post-doctorate fellow. Rowland was interested in ‘hot’ atoms (those with excess energy) and asked Molina to investigate what happened to CFCs. Within three months the pair had their answer – CFC gases rise into the stratosphere, where solar radiation breaks them into their component elements of chlorine, fl uorine, and carbon. Each chlorine atom is capable of destroying about 100,000 ozone molecules before becoming inactive. Their fi ndings were published in the scientific journal Nature in 1974, causing much debate until they were vindicated by the discovery of the hole in the ozone layer over Antarctica in the 1980s.
In 1975, Molina joined the faculty at Irvine, working with his wife Luisa (they married in 1973 and have a son, born in 1977). Molina felt restricted by his academic duties, however, and in 1982 he left the university to join the Jet Propulsion Laboratory at the California Institute of Technology, where he deduced that the Antarctic ozone hole was caused by ice crystals in the air amplifying the chlorine reaction. In 1989, he moved to MIT but returned to California in 2005, joining UC San Diego, and also to Mexico City, where he set up a centre for studies in energy and environment – the city’s air is much cleaner as a result. He and Luisa parted and in 2006 Molina wed Guadalupe Alvarez. He is a member of the US President’s Committee of Advisors in Science and Technology.
This text and the picture of the Nobel Laureate were taken from the book: "NOBELS. Nobel Laureates photographed by Peter Badge" (WILEY-VCH, 2008).
By Volker Steger
Mario Molina took a little while to sketch “what he got his Nobel Prize
for”. But the result is so clear, that one gets the message right away:
Spray cans destroy the ozone layer that protect us from UV rays.
But things got better, new spray cans cause less harm
to the ozone layer. Thanks to Mario Molina!
Mario Molina brauchte eine Weile für die Zeichnung seiner
Nobelpreis-Entdeckung. Doch das Ergebnis überzeugt, und man
versteht die Botschaft sofort: Sprühdosen zerstören die Ozonschicht,
die uns vor UV-Strahlung schützt.
Mittlerweile sind Sprühdosen viel weniger schädlich für die Ozonschicht
– dank Mario Molina!
When Local Became Global
by Adma Smith
“It’s a representation of the fact that we can protect our planet if we understand what we are doing to it,” says Mario Molina, looking again at his sketch. Against a backdrop of planet Earth, with its atmosphere represented by grey shading, a hand presses down on a spray can. The spray can is symbolic of the industrial chlorofluorocarbon (CFC) gases that, in an article published in 1974, Molina and his colleague Sherwood Rowland said were damaging the protective ozone layer in the stratosphere. CFCs were ubiquitously employed as propellants in spray cans and as refrigerants, and it took time to convince people of the link between these gases and the holes that were appearing in the ozone layer. But, eventually, a CFC ban came into force. “Fortunately society did get together, our hypothesis was tested scientifically and,” Molina continues, “The main point here is that through an international agreement the problem was solved.”
Back in the 1970s, there were no precedents for the idea that local behaviour could have a truly global impact. The CFCs are extremely stable compounds, and no matter where they are released they mix with the atmosphere, encircling the planet. Indeed, the most dramatic effects on the ozone layer were seen above the Antarctic, as far away as possible from the sites of the CFC emissions themselves. That apparent separation of cause and effect was one of the reasons for people’s initial scepticism. “We realised we had to be patient and persistent and we had to learn to communicate with the public at large, not just with other scientists,” recalls Molina. “We showed that society can respond to the scientific community when our reasoning is valid.”
Notice the sunrise at the top of the picture. Now, in the face of global climate change, Molina sees the historical example of the response to CFCs as providing a model for how the world can come together to tackle the threats posed by the changing climate. “Coming back to the precedent,” he says, “It can be done in a way that the economy’s not affected, jobs are not lost. Society was able to replace CFCs, the economy did not suffer; the other way around actually, it continued to grow. So, in some senses, the sunrise is a symbol of our hope that we’ll be able to solve all these problems.”