Ozone Depletion Analysis Essay Example

these gases like carbon dioxide and other pollutants trap heat in the lower atmosphere, they have a cooling effect on the stratosphere.

The formation of the ozone hole over Antarctica begins with sunlight returning during springtime in September. When this occurs, chemicals containing chlorine and bromine become active and break down ozone molecules within the stratosphere. Cold temperatures worsen this destruction as frozen cloud particles' surfaces play an essential role in this chemical reaction.

On September 19th, measurements taken by a NASA satellite revealed that the ozone hole had expanded to cover an area of 27.3 million square kilometers - surpassing North America's size. This exceeded even the previous record set in 1996 when it measured 26 million square kilometers. The satellite data also showed that within the most affected part of this hole, there was only one-third of expected ozone concentration for this time of year - raising concerns among researchers.

Balloon measurements conducted over South Pole reported a value of 92 Dobson units for ozone levels.The ozone hole's exceptional growth this year can be attributed to abnormally cold temperatures, exceeding normal altitudes, resulting in observed ozone loss up to an altitude of 24 kilometers. Typically, cloud particle freezing does not occur at this warm altitude. Scientists have found a link between recent stratospheric cooling and depletion of ozone molecules that absorb sunlight and warm their surrounding air. However, William J. Randel from the National Center for Atmospheric Research suggests that this explanation alone cannot explain the extremely low temperatures observed above Antarctica in August and September when there is limited sunlight. One possibility is that natural weather conditions in the lower atmosphere generate pressure disturbances that

ripple into the stratosphere. During springtime ozone loss, planetary waves traditionally slow down the destruction of ozone by warming the polar stratosphere. However, there has been a recent decrease in the number of these waves hitting both the Arctic and Antarctica. While one computer model predicted that greenhouse warming would reduce these waves, other models contradict this prediction. The recent cooling trend raises concerns about potential ozone depletion but is not considered conclusive evidence for it.
Scientists at an American Geophysical Union meeting reported that during the previous winter, there was a record-breaking occurrence of polar stratospheric clouds forming in the Arctic. These clouds lasted for a longer duration than usual, resulting in significant damage to the ozone layer. According to Michael J. Kurylo, a NASA representative leading the SAGE III Ozone Loss and Validation Experiment (SOLVE), these clouds play a crucial role in depleting the ozone layer by allowing inactive chlorine compounds from humanmade chlorofluorocarbons to transform into a reactive form within the particles present in the clouds. This transformation leads to destruction of ozone molecules. Additionally, these clouds release nitric acid which reduces nitrogen concentration in the stratosphere. Nitrogen is known to counteract chlorine's ability to destroy ozone, so when denitrification occurs as observed during this period, chlorine is able to attack ozone without any hindrance. International researchers presented preliminary results at a recent meeting, revealing an unexpectedly high number of polar stratospheric clouds in the Arctic region last winter. The data used for these findings were collected between December 1999 and March 2000 using instruments from NASA's SOLVE project led by Eric J. Jensen at Ames Research Center in Moffett Field, Calif., indicating

severe instances of denitrification were observed during this time frameHowever, further analysis is needed before definitive statements can be made about the extent of this phenomenon and its potential impact on the observed ozone losses last winter. Katja Drdla from Ames indicates that computer models indicate a possible decrease of 40 to 50 percent in ozone in the lower stratosphere even without denitrification. In cases where denitrification is severe, this total loss could rise to 60 to 80 percent.

During the same meeting, Azadeh Tabazadeh presented her team's independent satellite measurements and discovered that polar stratospheric clouds persisted for longer periods during the most recent Arctic winter compared to the coldest winters of the 1990s. Tabazadeh's team also detected signs of denitrification; however, it was not severe. Based on her observations, she believes that most of the ozone loss during this winter was not due to denitrification.

These findings support a previous SCIENCE study by Tabazadeh et al., published on May 26th, which cautioned about the abnormally long-lasting polar stratospheric clouds in the Arctic. The researchers analyzed satellite measurements from a typical Antarctic winter in the 1990s and two of the coldest Arctic winters in that decade. They found that these clouds lasted only half as long in the Arctic compared to Antarctica.Tabazadeh's mathematical modeling indicates that if Arctic stratospheric cooling continues at a rate of 2 degrees C per decade, the duration of these clouds could double in the coldest winters starting in 2010. However, if the cooling rate slows to only 1 degree C per decade, this timeline could be pushed back until the 2030s. Additionally, Tabazadeh's team suggests that as polar stratospheric clouds become

more persistent, severe denitrification could lead to a 30 percent increase in Arctic ozone loss. Drew T. Shindell from NASA's Goddard Institute for Space Studies commends Tabazadeh's well-executed study and highlights the importance of global data sets from satellites in understanding geographical variations, despite localized information obtained through aircraft studies and ground-based measurements. Michael J. Newchurch from the University of Alabama at Huntsville connects answering this question to rising carbon dioxide levels and human-induced climate change by noting that while Earth's surface warms up, its stratosphere cools down. Despite all this research and analysis, Tabazadeh remains skeptical about the long-term cooling trend in the Arctic and suggests it may eventually slow down or even reverse. Furthermore, he doubts that the Arctic will experience yearly ozone holes like Antarctica does on an annual basis.