Mario Molina
Gave early warning about CFCS eating a hole in the ozone layer
MARIO MOLINA, who has died aged 77, was a Mexican-born chemist who shared the 1995 Nobel Prize in Chemistry, with Paul Crutzen of the Max Planck Institute and Sherwood Rowland of the University of California at Irvine, for their discovery that chlorofluorocarbons or CFCS contribute to the depletion of the ozone layer.
In the early 1970s CFCS, used as refrigeration fluids and propellants for aerosolspray products, were seen as an industrial success story. Engineered to be chemically inert, they were thought to be safe.
But in 1972 Rowland attended a lecture by the British scientist James Lovelock, inventor of an instrument with which he had detected CFCS in air over the Atlantic. Lovelock was convinced the chemicals were harmless, but Rowland suspected they might not be at high altitudes. He and Molina set out to investigate.
They theorised that solar radiation causes CFCS to decompose in the stratosphere, from about eight to 50 km above the Earth’s surface, releasing atoms of fluorine, chlorine and chlorine monoxide. These, they argued, could destroy large numbers of molecules in the ozone layer which protects the earth from solar radiation that causes skin cancer, crop damage and other problems.
Building on work by the atmospheric scientist Paul Crutzen, they calculated that if CFC use continued unchanged, the ozone layer would be depleted within decades. In 1974, however, when they published their research in Nature, it was widely dismissed in the chemical industry, the president of one firm suggesting that the research had been “orchestrated by the Ministry of Disinformation of the KGB’’.
But the strength of their case was confirmed by the US National Academy of Sciences, and in 1978 aerosols containing CFCS were banned in the US, followed by some other countries.
Doubts remained, though, and a Nasa satellite measuring ozone levels provided no evidence of depletion – because, as discovered years later, its computers had been programmed to discard low figures as being spurious. In 1985, scientists working for the British Antarctic Survey announced the discovery of
a significant thinning in the ozone layer above the South Pole, proving that the danger identified by Rowland and Molina was real. Their measurements showed 40 per cent less ozone than had been detected 20 years earlier.
In 1987 governments negotiated the “Montreal Protocol” to phase out CFCS, as a result of which the ozone layer is recovering and should be close to full repair by the 2080s.
José Mario MolinaPasquel y Henríquez was born on March 19 1943 in Mexico City to Roberto, a lawyer and diplomat, and Leonor, née Henríquez. He attended boarding school in Switzerland before continuing his studies in Mexico, where he took a degree in Chemical Engineering at the National Autonomous University of Mexico. After further study in Paris and Germany, he went on to take a doctorate at the University of California, Berkeley, in 1972.
Molina’s initial interest was in high-power chemical lasers, but finding they were being developed elsewhere as weapons, he changed his field of research and in 1973 joined Rowland’s laboratory group at the University of California, Irvine.
He would later work at the Jet Propulsion Laboratory in Pasadena, California; the University of California, San Diego; and as a professor at the Massachusetts Institute of Technology.
He served on the President’s Council of Advisors on Science and Technology under Bill Clinton and Barack Obama, who in 2013 gave him the Presidential Medal of Freedom.
Molina’s first marriage, to Luisa Tan, was dissolved. He is survived by his second wife Guadalupe, a son from his first marriage and three stepchildren.
Mario Molina, born 19 March 1943, died 7 October 2020