Professor Sherwood Rowland was one of the scientists responsible for raising awareness of the damage being caused to the earth's ozone layer by a group of chemicals known as chlorofluorocarbons (CFCs). His work in the field, which began in the 1970s, has led to a worldwide phasing out of these substances and the gradual, natural repairing of the hole in the ozone layer.
Frank Sherwood Rowland was born in Delaware, Ohio in 1927. His father was the Chair of Mathematics at the city's Ohio Wesleyan University (OWU) and filled the family home with books, encouraging his three sons with a passion for knowledge of all kinds.
Rowland received his BA from OWU in 1948. He went on to the University of Chicago, where he gained his PhD four years later, having studied under Professor Willard Libby, developer of the Carbon-14 dating technique. Following work on nuclear chemistry at Princeton and the University of Kansas, he became part of the team which established the University of California Irving (UCI) in 1965.
Rowland had first encountered discussion of CFCs in the atmosphere during a lecture by James Lovelock in 1972. His work on CFCs and the ozone layer began the following year, working with the postgraduate student Mario Molino, who had in turn been inspired by the work of Paul Crutzen on nitric oxide and ozone.
The stratospheric ozone layer, 20-60 kilometres above the Earth, is composed of a molecule containing three oxygen atoms, which serves as a filter to protect life from excessive solar radiation. CFCs were widely used in aerosols, refrigerators and air-conditioning systems. Although they seemed harmless, Molino and Rowland were concerned about the effect of these chemicals on the layer, as they decomposed in sunlight and the resulting chlorine atoms combined with ozone.
The results of their research were published in Nature in June 1974, where they made their bold assertion that "Photodissociation of the chlorofluoromethanes in the stratosphere produces significant amounts of chlorine atoms, and leads to the destruction of atmospheric ozone." Or, in layman's terms, as Rowland later explained, "Mario and I realised this was not just a scientific question, but a potentially grave environmental problem involving substantial depletion of the stratospheric ozone layer... Entire biological systems, including humans, would be at danger from ultra-violet rays."
Their ozone depletion theory was at first disputed by the chemical industry and especially by DuPont, the inventor and main manufacturer of CFCs, whose then chairman considered it "a science fiction tale...a load of rubbish...utter nonsense". Rowland recalls that the trade magazine Aerosol Age ran "an article calling us agents of the Soviet Union's KGB, who were trying to destroy American industry." By 1978, however, the use of CFCs in aerosols had been banned in the US and Canada.
During 1983 a British Antarctic Survey team, led by the geophysicist Joe Farman, confirmed by observation that the theoretical danger to the ozone layer was proven in the real world: there was indeed a "hole" in the layer above Antarctica, which grew during the spring period. A paper published two years later would increase the pressure for a global ban on ozone-depleting chemicals. Team member Jonathan Shanklin told The Independent that they had anticipated there would be no effect on ozone at the poles: "The results were totally unexpected. Without Rowland's work we would not have been looking in the way that we were."
The Vienna Convention for the Protection of the Ozone Layer was agreed in 1985. Four years later the related Montreal Protocol, on phasing out the use of CFCs, became effective and has since been ratified by 197 countries. The ozone layer is expected to recover completely by 2050.
Rowland was elected to the National Academy of Sciences in 1978 and was President of the American Association for the Advancement of Science in 1993. Rowland, Molina and Crutzen shared the 1995 Nobel Prize for Chemistry "for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone".
Spurning retirement, Rowland had continued his research in the areas of pollution and global warming. He told a White House climate change meeting in 1997: "Isn't it a responsibility of scientists, if you believe that you have found something that can affect the environment, isn't it your responsibility to do something about it, enough so that action actually takes place?" He emphasised the point: "If not us, who? If not now, when?"
During 2010 Rowland was involved in work on the atmospheric contaminants around the BP spill in the Gulf of Mexico, analysing the impact of the oil and the dispersants used to break it down. His paper on the subject was his 425th and last.
Kenneth Janda, Dean of the Physical Sciences department at UCI, said: "We have lost our finest friend and mentor. He saved the world from a major catastrophe: never wavering in his commitment to science, truth and humanity and did so with integrity and grace."
Frank Sherwood Rowland, scientist: born Delaware, Ohio 28 June 1927; Nobel Prize for Chemistry (shared) 1995; married 1952 Joan Lundberg (one son, one daughter); died Newport Beach, California 10 March 2012.