False-color view of total ozone over the Antarctic pole.A giant hole in our ozone layer, larger than Russia and Canada combined, has appeared over Antarctica, but it’s not the result of global warming. On Thursday, the World Meteorological Organization (WMO) blamed the record-sized hole in our ozone layer as a phenomenon that “fluctuates in size during the season in polar regions.” With the return of extreme cold in the stratosphere (upper atmosphere) and sunlight to Antarctica, chlorine radicals are created that destroy ozone molecules. The ozone layer is what protects most life on Earth from the harmful rays of the sun.
The Antarctica hole begins when winter arrives and a “vortex of winds develops around the pole, and isolates the polar stratosphere.” Once temperatures drop below -109 degrees Fahrenheit (-78 degrees Celsius), thin clouds made of “ice, nitric acid, and sulfuric acid” are formed. Chemical reactions on the ice crystals in these thin clouds “release active forms of CFCs”, which in turn destroy ozone molecules. As Antarctica enters into its summer phase (and the Northern Hemisphere enters winter), the ozone hole slowly recovers.
One reason the WMO scientists may be saying that climate change is not the culprit is because according to the theory of global warming, increased levels of carbon dioxide (CO2) and other greenhouse gases are supposed to cause an increase in the average temperature of the Earth’s atmosphere because of the so-called ‘greenhouse effect.’ The theory also predicts that the upper atmosphere will warm from trapped heat, and then the lower atmosphere (surface of the Earth) will warm afterwards. Warmer air in the stratosphere prevents these chemical reactions from occurring, which eventually lead to ozone destruction.
Except since 1979, when orbiting satellites began taking temperature measurements, the exact opposite has happened. The orbiting satellites, which continuously measure Earth’s atmosphere, show that the upper atmosphere has not warmed significantly (less than the margin of error). In fact, they show no statistical warming when compared to the lower atmosphere (the air around us). This comes from data that is scrupulously analyzed by scientists from all over the world as well as two separate entities.
Many scientists blame the use of chlorofluorocarbons (CFCs), which were widely used in aerosol products and refrigeration units, for the ozone hole that contracts and expands seasonally over Antarctica. Scientists discovered in the 1970s that CFCs are so stable that only “exposure to strong UV radiation breaks them down.” When that happens, the CFC molecule releases atomic chlorine. “One chlorine atom can destroy over 100,000 ozone molecules,” which is faster than what is naturally created.
Not all ozone depletion is man’s fault. When volcanoes erupt, they produce large amounts of tiny particles known as aerosols, which increase chlorine’s effectiveness at destroying ozone. It should also be noted that the ozone hole over Antarctica is not an actual hole, but an area with lower amounts of the molecule ozone (better known on the streets as O3). Since recordkeeping began, ozone has depleted to more than 60 percent of what’s considered a normal amount.
Using information from weather balloons, ground-based measurements, and satellite data of Earth’s ozone layer, scientists then painted a picture of how CFCs were affecting the stratospheric ozone layer. Indeed, most nations banned the use CFCs in 1987 under the Montr√©al protocol. And only last year, the World Meteorological Organization (WMO) said it “detected the first signs of ozone recovery.”
The current ozone hole over Antarctica is not the largest, though. In 2000 and 2006, ozone holes larger than 10.9 million square miles (28.2 million square km) have appeared over the frozen continent. Ozone persists in our atmosphere (stratosphere) at low levels, and makes up roughly 0.6 parts per million (ppm) of the Earth’s atmosphere.
Ozone is also produced from the combustion of fossil fuels but is considered a “short-lived greenhouse gas” that decays much more quickly than CO2. Other sources include decaying organic matter. And unlike CO2, it doesn’t spread evenly across the globe and can build up in certain areas, especially in large industrialized areas. Strong winds also carry ozone from the air around us and into the stratosphere.
Not all ozone is bad, though. Many countries and municipalities use ozone to kill microorganisms in drinking water and in the air. Because of its caustic nature, it also has many industrial uses. You only have to look in your medicine cabinet to see where ozone is used in the preparation of “pharmaceuticals, synthetic lubricants, and many other commercially useful organic compounds.”
