UMaine News

Nobel Laureate F. Sherwood Rowland, Ozone Researcher, to Speak at UMaine

Contact: Prof. Mark Wells (207) 581-4322; Tom Weber (207) 581-3777

ORONO — F. Sherwood Rowland, who shared the Nobel Prize for chemistry in 1995 for his pioneering work on the formation and depletion of atmospheric ozone, will deliver a lecture March 13, at the University of Maine’s Buchanan Alumni House.

Rowland, a professor of chemistry and earth system science at the University of California, Irvine, is scheduled to speak at 4:30 p.m. The event, which is free and open to the public, is sponsored by UMaine’s School of Marine Sciences, Climate Change Institute, Department of Chemistry and the Maine Section of the American Chemical Society. Rowland’s afternoon seminar is titled “Our Changing Atmosphere: The Ozone Hole and Carbon Dioxide.” A reception will follow.

Rowland and Mario Molina, now a professor at the University of California, San Diego, published a widely noted and controversial paper in the journal Nature in 1974 on the threat to the ozone layer from chlorofluorocarbon (CFC) gases known as freons. The gases were common at the time in aerosol spray cans, as the cooling medium in refrigerators, in plastic foams and other industrial applications.

Rowland and Molina had based their findings on the important contributions of scientists such as James Lovelock of England, who invented the ultrasensitive electron capture detector that allowed him, in 1970, to measure extremely low amounts of organic gas in the atmosphere. With his device, Lovelock revealed that man-made, chemically inert CFC gases had already spread throughout the atmosphere in both the northern and southern hemispheres.

Paul Crutzen of the Netherlands had also found in 1970 that nitrogen oxides acted as catalysts in the depletion of ozone. Two American scientists, Richard Stolarski and Ralph Cicerone, revealed the same ozone-destroying process with regard to chlorine atoms in the atmosphere.

In 1973, Rowland and Molina discovered that the CFC gases they studied were capable of remaining in the atmosphere for a century or more. They also found that the destruction of these molecules by intense solar ultraviolet radiation released chlorine atoms, causing a chain reaction capable of depleting a significant fraction of the Earth’s protective stratospheric ozone layer.

Their article the next year received a great deal of attention, not all of it favorable. The CFC gases were widely used back then, after all, and thought to be environmentally safe. Rowland and Molina’s findings did generate sufficient environmental concern, however, that certain restrictions were placed on the release of CFC in the late 1970s and early 1980s. In 1985, the debate over CFCs spread worldwide when the Englishman James Farmer and his colleagues observed a massive springtime loss of ozone over Antarctica, and a smaller loss in the temperate zones of the northern hemisphere. Both depletions were found to be caused chiefly by industrially manufactured gases.

Under the Montreal Protocol of the United Nations, established in 1987, the CFC compounds are now banned worldwide.

For their valuable scientific contributions, Rowland, Molina and Crutzen were awarded the Nobel Prize in chemistry in 1995. In announcing the prize, the Royal Swedish Academy of Sciences remarked: “The thin ozone layer has proved to be an Achilles heel that may be seriously injured by apparently moderate changes in the composition of the atmosphere. By explaining the chemical mechanisms that affect the thickness of the ozone layer, the three researchers have contributed to our salvation from a global environmental problem that could have catastrophic consequences.”