Susan Solomon
Chemical Engineer • USA
“The ozone hole above Antarctica has been one of the most important environmental stories of the 20th century”
Susan Solomon is a specialist in atmospheric chemistry, known for her work on the physico-chemistry of the hole in the ozone layer above Antarctica. A researcher at the National Oceanic and Atmospheric Administration (NOAA), she led an expedition to Antarctica in 1986/87, where she collected critical data backing up the idea that the hole in the ozone layer was not a natural phenomenon. An Antarctic glacier was named after her in recognition of her work.
In 1985, scientists at the British Antarctic Survey shocked the world by announcing that they had measured a massive loss of ozone above Halley station. Scientists worldwide puzzled over the cause of the unexpected phenomenon that the world now knows as the Antarctic ‘ozone hole’, which proved to be one of the most important environmental stories of the 20th century. I was the primary author of a paper putting forth a hypothesis that the reason for the ozone hole might be an unanticipated chemistry involving chlorine (a reaction between hydrochloric acid and chlorine nitrate) on the surfaces of the polar stratospheric clouds that form in the uniquely frigid Antarctic stratosphere. In 1986, I had the good fortune to go to Antarctica to measure not only ozone but also a range of the chemicals that would be indicators of such chemistry. The source of nearly all atmospheric chlorine is the chlorofluorocarbon that was then ubiquitous across modern life: in refrigerators, air conditioning, solvents, foams, and more. My speculation about chlorine and clouds would convert polar chlorine to forms that could devour ozone much faster than previously thought. It would also mean that humankind, not nature, was the fundamental cause of the disappearing Antarctic ozone. Our data miraculously bore fruit shortly after they were collected, showing very high levels of chlorine dioxide totally unlike other places on Earth. While our measurements were the first, they were by no means the only pieces of evidence needed to establish the cause of the ozone hole beyond reasonable doubt. Independent observations of many other key chemicals quickly followed. Within a few years, the world agreed to the Montreal Protocol to limit and eventually phase out emissions of chlorofluorocarbons, a landmark global environmental agreement owing its success to the strength of many different observations by dozens of scientists. Chloroflurocarbons live in the atmosphere for many decades, so the chlorine already here will decay only very slowly and will continue to create Antarctic ozone holes for decades to come, but the hole will eventually close sometime around 2060. By its nature and culture, science seeks the truth, that’s its beauty and value. The challenge is to communicate to the public these aspects, along with what we do and don’t know. In the tale of the ozone hole, science has told a remarkable story that has resonated around the world.