He attended boarding school in Switzerland before continuing his studies in Mexico, where he received a chemical engineering degree from the National Autonomous University of Mexico in 1965; in Germany, where he received a graduate degree from the Univers

recalled co-opting a bathroom in his family’s home for a makeshift laboratory, where he whiled away hours experimenting with chemistry sets.

After leaving UC-Irvine in 1979, Molina joined the Jet Propulsion Laboratory at the California Institute of Technology. He later was a professor at the Massachusetts Institute of Technology and at the University of California at San Diego, where he had an appointment at the Scripps Institution of Oceanography.

He served on the President’s Council of Advisers on Science and Technology under Bill Clinton and Barack Obama. In 2013, Obama awarded Molina the Presidential Medal of Freedom, the US’s highest civilian honour.

His first marriage, to Luisa Tan, also a chemist, ended in divorce. Survivors include his wife, Guadalupe Alvarez of Mexico City; a son from his first marriage, Felipe Molina of Boston; three stepchildren; two brothers; a sister; and two grandchildren.

Until his death, Molina was a prominent voice in debates about how best to combat climate change. He spoke to the media, testified before the US Congress and generally sought to persuade the public of the importance of participating in environmental conservation.

“We started something that was a very important precedent,” he told the New York Times when Rowland died in 2012. “People can make decisions and solve global problems.”

Molina devoted particular attention to reducing pollution in Mexico City, where residents often endure an oppressive blanket of smog hanging over the metropolis.

“We see clearly that we have a long way to go to have a clean city, clean air,” he told the Chicago Tribune in 2007. “We have some beautiful green mountains that, on a day like today, we just have to imagine. It motivates me that we need to work harder.”

Mario Molina, chemist, born 19 March 1943, died 7 October 2020