In a recent report issued by Nature, an international science journal, a record-breaking hole in the ozone layer was observed over the Arctic in the winter of 2010/11. Through ideal and sustained circumstances for ozone depletion, the first Arctic ozone hole comparable to the one observed over Antarctica has been recorded.
Early each spring, both polar regions of the Earth experience some chemical ozone destruction. Since the 1980s, almost complete degradation of the ozone layer has been observed in Antarctica, growing in size since it was first discovered. Generally, the Arctic is much more variable and lower in magnitude, however a combination of persistently cold stratospheric temperatures and strong wind patterns developed record setting levels of depletion. These levels were as high as 80% in regions at 18-20 kilometers altitude, with the hole covering an area five times the size of California as reported by Nature. They have said that future events of this magnitude or higher can be predicted, however the ideal conditions presented may indicate that this will be an infrequent occurrence.
The ozone depletion at each of the poles is centered in the lower stratosphere of the polar vortex, a large cyclone that forms each winter and lays stagnant at the poles. The exceptionally cold temperatures of the upper atmosphere at the poles combined with a layer of condensed water molecules and nitric acid create ideal conditions for ozone destruction. Here chlorofluorocarbons (CFCs), previously used for things such as refrigerants, release chlorine molecules which in turn attack the ozone. This reaction converts the UV-radiation absorbing ozone into regular oxygen and consequently destroys the protective layer.
The questions surrounding this event are centered on what these findings imply for the state of the ozone in the Arctic. Normally, the Arctic depletion is lower due to higher temperatures than the Antarctic, but it was shown that for small time spans, the hole stretched to inhabited regions of Russia, Mongolia and Eastern Europe. The increased exposure was short enough to have little effect but it raises concerns of larger holes in the future. In previous years the Antarctic hole has had years so large that it covered the entire continent and stretched to parts of South America. It can be reasoned that these conditions were of low probability but the risk of increased skin cancers from UV-ray exposure isn’t something to be taken lightly.
Since the initial signing of the Montreal Protocol in 1989, ozone-depleting chemicals such as CFCs have been in steady removal from industrial standards globally. As of 2009, 196 countries, including all of the United Nations members, have ratified the Montreal Protocol. It has been observed that the atmospheric concentrations of the most important CFCs have either leveled off or decreased. Predictions state that if all signed countries follow the requirements of the treaty the atmosphere should return to pre-industrial levels by the year 2050.
Ozone depletion and the enormous impact that it has on the world, both in nature and human society, is something that serves as a reminder of the negative impact of human development. Understanding the consequences of what we produce and consume is crucial to prevent scenarios of similar or greater impact. While complex, protecting society from these problems is an important moral obligation to consider as both a student and professional.
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