Ozone hole theories

In 1984, a remarkable and totally unpredicted phenomenon was discovered by the British Antarctic Survey, the so-called ozone hole. The discovery of ozone depletion over Antarctica during the spring period provided the first observational support for the possible effect of CFCs on the stratospheric ozone. However, the observation of ozone loss did not indicate its cause. From 1984 to 1988, several theories were postulated from CFC chemistry to atmospheric dynamics or even to cosmic electron fluxes. It was not until 1988, with the results of the 1987 Airborne Antarctic Ozone Expedition, that a probable link with CFCs was established. This prompted the Natural Resources Defense Council, an American pressure group, to sue the EPA to fulfill its 1980 promise to seek legislation to further control the manufacture and use of CFCs in the United States of America. 

In 1986, the National Aeronautics and Space Administration (NASA) chose Solomon (then 30 years old) to lead a team to Antarctica to sort out the right explanation for the ozone hole. Experiments during that visit to Antarctica showed that her cloud theory was correct, and a second... 

Three chemists, Paul J. Crutzen, Mario J. Molina, and F Sherwood Rowland (Figure 10.3), formulated the theory of the ozone hole and shared the Nobel Prize... 

The discovery of the ozone hole came during a period in which I was heavily involved in various international studies on the potential environmental impacts of a major nuclear war between the NATO and Warsaw Pact nations, an issue to which I will briefly return to in one of the following sections. Because so many researchers became quickly involved in the ozone hole research, initially I stayed out of it. Then, in early 1986 I attended a scientific workshop in Boulder, Colorado, which brought me up-to-date with the various theories that had been proposed to explain the ozone hole phenomenon. Although it turned out that some of the hypotheses had elements of the truth, in particular the idea put forward by Solomon et al. [58]. of chlorine activation on the surface of stratospheric ice particles, followed by reactions (23) and (24). 

Paul continued to make major contributions to stratospheric chemistry. For example, he explained how nitric acid clouds cause the Antarctic ozone hole. At the same time, he also turned his attention to the troposphere, which is the air layer that connects with the biosphere and where weather and climate take place. The troposphere is also prone to air pollution, while it is cleaned by oxidation reactions. The self-cleaning capacity relies on the presence of reactive hydroxyl radicals that convert pollutant gases into more soluble compounds that are removed by rain. The primary formation of hydroxyl radicals in turn is from ozone. While most ozone is located in the stratosphere, protecting life on Earth against harmful ultraviolet radiation from the Sun, a small amount is needed in the troposphere to support the self-cleaning capacity. While previous theories had assumed that tropospheric ozone originates in the stratosphere, Paul discovered that much of it is actually chemically formed within the troposphere. The formation mechanism is similar to the creation of ozone pollution in photochemical smog . 

In 1974, scientists proposed a theory to explain the observation of a hole in the ozone layer over Antarctica, which is shown in purple. This hole is about the size of North America. 

In 1985, a British team at Halley Bay Station, Antarctica, discovered the existence of a hole in the ozone layer above that continent. This totally unexpected phenomenon needed an explanation, and Susan Solomon—a young National Oceanic and Atmospheric Administration (NOAA) scientist—first proposed a good theory for it. While attending a lecture on polar stratospheric clouds, she realized that ice crystals in the clouds might do more than just scatter light over the Antarctic. Her chemist s intuition told her that the ice crystals could provide a surface on which chemical reactions of CFG compounds could take place. 

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