Stratospheric Ozone and the Biosphere
1. B > E – Montreal Protocol and Human Help
The Vienna Convention in 1985 was a big step forward in promoting research of the ozone layer and how CFC’s affect it. As researchers began realizing that human activities and human made products where slowly destroying the ozone layer, scientists from around the world created the Montreal Protocol on Substances that Deplete the Ozone Layer on September 16, 1987. The Protocol was based on the Vienna Convention in 1985 that established international research on the ozone layer and how it is affected by CFC’s. Through this it was in 1985 as well that researchers first noticed the hole in the ozone layer above Antarctica. The Montreal Protocol called for the elimination of chlorofluorocarbons and substances that are destroying the ozone worldwide. Many people feel that this Protocol will make humans more aware of what substances aid in ozone depletion and to make sure and not buy or use the products. Because many people already own products that not easily replaced and contain “ozone-depleting substances, it is highly recommended that these products are properly cared for. This will make sure that none of these toxic substances are released into the atmosphere and make their way to the ozone layer in the stratosphere.
In 1985 the Montreal Protocol was signed by twenty-four countries and all of the European Economic Community. To date the Montreal Protocol has been signed by 191 nations including the United States and amendments have been adopted since then. After the initial creation of the Montreal Protocol in 1987, scientists were astounded to learn that there was a lot more damage to the ozone layer than was initially expected. In order to have a better impact on the ozone layer, the countries and parties involved in the Protocol decided to end all production of halocarbons by 1994 and chlorofluorocarbons in developed countries by 1996.
Ratification of:Vienna Convention / Montreal Protocol / London Amendment / Copenhagen Amendment / Montreal Amendment / Beijing Amendment
Total number of countries / 191 / 191 / 185 / 176 / 152 / 124
This table shows the agreements made to protect the ozone layer in the stratosphere and their approval rates.
References:
http://www.ec.gc.ca/ozone/docs/UO/faq/EN/faq.cfm
http://www.epa.gov/ozone/science/sc_fact.html
http://www.idph.state.il.us/envhealth/factsheets/ozone.htm
http://www.epa.gov/sunwise/kids/kids_ozone.html
http://www.theozonehole.com/montreal.htm
2. B > E - aircrafts
Even though the ozone layer protects Earth and its life forms from the harmful radiation of the sun, humans are causing damage to it. One way that humans are causing harm to the ozone layer is by flying supersonic transport and military jets through this part of the stratosphere which extends between 10 and 50 kilometers above Earth’s surface. Not only do we fly jets through the ozone, the jet engines themselves emit condensable gasses like sulfuric acid, nitric oxide gas and water vapor that harm the ozone.
References:
Chiras, Daniel D. (1998). Environmental Science: A systems Approach to Sustainable Development. Belmont: Wadsworth Publishing fifth edition (381-387).
http://climatelab.org/Airplane_emissions
http://www.epa.gov/Ozone/science/sc_fact.html
3. A > E > B – UV radiation – Humans
Stratospheric ozone is extremely important to all biological life on Earth, without it life on Earth would not be possible. The ozone layer acts like a shield and absorbs a large amount of the solar electromagnetic radiation within the UV range that comes from the Sun. There are three major categories of UV radiation or UV Rays that affect Earth and they are based on their wave length, they are UV-A, UV-B and UV-C. In general it is key to note that the shorter the wavelength of UV radiation the more damage it can cause to organisms on Earth. UV – A radiation reaches the Earth in the greatest quantities (because ozone is less effective) however it causes the least amount of damage to organisms. UV – B radiation can be and is very harmful to organisms despite the fact that most of it is absorbed in the stratosphere by the ozone layer. In small quantities UV-B can be good because it stimulates the production of vitamin D, however in large does it can cause harm to many. Humans with darker pigments or more melanin in their skin can deal with more exposure to UV-B than humans with lighter skin because the melanin helps block it out. Unfortunately the largest rate of skin cancer is found in Queensland, Australia where most of the citizens are light skinned Northern Europeans. UV –C radiation has the potential to be the most damaging of all three wavelengths; none of its radiation is able to get through Earth’s troposphere.
Although the stratospheric ozone is a great source of protection from harmful UV radiation there are many other factors other than the ozone that also influence that amount of UV – B radiation that reaches the Earth. Rain, air pollution, altitude, cloud cover, time of day, season and the percentage of light that is reflected off of different land masses all have an effect. Yet it is without the protection of the ozone layer that humans would be in serious trouble of over exposure to UV radiation. In large amounts UV radiation is not only capable of causing skin damage but can also cause eye damage, early aging, immune suppression (making us more susceptible to infectious diseases) and damage to genetic material like DNA and RNA. Even though DNA and RNA can absorb small amounts of UV radiation they are harmed when they absorb it, leading to an increased risk of skin cancer or basal carcinomas.
UV radiation can increase the likelihood of cataracts forming in the eye of many organisms. Cataracts cause the lens in the eye to look milky and they give the sense of a continuously cloudy vision. If cataracts are not treated they could potentially lead to blindness. It is noted by the EPA that one in every five Americans will develop some type of skin cancer in their life time, and that one American dies every hour. Melanoma is perhaps the scariest form of skin cancer and because it may take ten to twenty years to develop, many doctors feel that it usually occurs from sunburns obtained in the patient’s youth. Two other forms of skin cancer are Basal cell carcinoma and Squamous cell carcinoma. Basal cell carcinomas are slow spreading small and fleshy tumors that grow around the head and neck of an individual. Squamous cell carcinomas are red, patchy and scaly tumors that can grow into large groups and spread to other parts of the body.
The figure below shows the occurene of skin cancer (black) and squamous cancer (gray) for selected cities in the United States during July 1992.There are many things that you can do in order to protect yourself from the increasing amount of UV-B radiation reaching the earth. It is imperative to limit you exposure to the sun, especially between 10am and 3pm where they sun’s rays are at their peak. While out it in the sun you should always wear: polarized sunglasses, hats (wide-brimmed if possible), light weight long-sleeved shirts and plants. It is also highly recommended to wear sunscreen with an SPF or Sun Protection Factor of 15 or higher. The sunscreen should be applied before exposure to the sun and reapplied continuously throughout the day, especially after swimming or any physical activity.
References:
http://www.epa.gov/ozone/science/sc_fact.html
http://www.epa.gov/sunwise/uvandhealth.html
http://ozone.unep.org/Assessment_Panels/EEAP/eeap-report2006-FAQ.pdf
http://science.jrank.org/pages/4974/Ozone-Layer-Depletion-importance-stratospheric-ozone.html
jwocky.gsfc.nasa.gov/index.html.
http://www.ciesin.org/TG/HH/ozhlthhm.html
4. E > B –Stratospheric Ozone Depletion on Plants and Ecosystems
The good ozone in the stratosphere helps protect life of Earth by shielding it from harmful UV radiation, in particular UV-B radiation. Depletion of the ozone layer in the stratosphere can cause more harmful UV-B radiation to reach the Earth and it has the potential to harm many plants, ecosystems and can even the alter biochemical cycles. Even though plants need sunlight to grow, too much UV-B radiation can alter a plants growth process by degrading their photosynthetic pigments. It can also cause mutations, stunt the growth of a plant and even cause damage to the leaves of the plants. Scientists are worried that the depletion of the ozone layer will cause a loss in species diversity of plants, thus reducing food supply and oxygen production world-wide. More importantly the loss of plant species means that the balance of many ecosystems will be altered and disrupted because plants are the base of the food chain. The decline in ozone and increase in UV radiation can also affect crops like corn, wheat and rice and hinder commercially valuable trees.
If ozone depletion does persist and a large increase in UV-B radiation does occur, life in the ocean would be forced down to greater depths because UV radiation can penetrate clear water. Phytoplankton or free floating plant life is the basis of the food chain in the ocean. Because plants need sunlight to grow, phytoplankton typically lives in the euphotic zone where there is enough sunlight so they can grow. Where they live in the euphotic zone depends on the currents of the wind and waves. Scientists have found that overexposure of phytoplankton to UV-B radiation has caused a decrease in their population numbers. Slight increases in exposure to UV-B radiation also has an effect on animals like fish, crabs and shrimp while there are in their larval state, causing many organisms to grow smaller in stature, limiting the population size of the animals that consume them. Coral polyps that make up coral reefs can also be affected by excess UV radiation. Even though corals produce their own type of “sunscreen” or UV-absorbing compounds to protect themselves from the potential damage of UV radiation, when corals become overly stressed from the warming of ocean water they are unable to create their sunscreens at a steady rate.
References:
http://www.ec.gc.ca/ozone/docs/UO/faq/EN/faq.cfm
http://www.epa.gov/ozone/science/effects/index.html
http://science.jrank.org/pages/4974/Ozone-Layer-Depletion-importance-stratospheric-ozone.html
http://www.marinebiology.org/coralbleaching.htm
http://docs.google.com/gview?a=v&q=cache:H2kNRRtWfNgJ:www.marine.usf.edu/pjocean/packets/sp00/sp00u1le3.pdf+ozone+depletion+and+coral&hl=en&gl=us&sig=AFQjCNGbXkIj84VJFi5BNTJcqFHqYw-kGg
5. B > E > A – CFC’s and ODO’s
The stratospheric ozone is largely becoming depleted because of human made chemical compounds called chlorofluorocarbons or CFC’s that are disrupting its balance. CFC’s are unstable molecules that are made up of atoms of fluorine, carbon and chlorine. Winds can carry CFC’s into the stratosphere and once there CFC molecule can destroy roughly 100,000 ozone or O3 molecules, destroying the ozone faster that it was originally created. Because CFC’s do not break down in the lower atmosphere they can remain there from twenty to over one hundred years.
Chlorofluorocarbons are found in soap and foam and production, are used in the propellants of aerosol cans and can be found in solvents, air conditioners and refrigerators. CFC’s were used a lot in the 1950’s because they are flame resistant, stable, inexpensive to make and have low toxicity levels. Now days many researchers are looking for ways to remove CFC’s from the atmosphere. Unfortunately because they are so stable, they are no natural ways to get rid of them in the atmosphere and can only be broken down by UV radiation in the stratosphere. According to the EPA, scientists do feel that it is possible to balance the natural production and destruction of the ozone layer, only if all CFC’s and ODO’s are complete eliminated. ODO’s or ozone-depleting substances can also be described as halocarbons. They include the halons (which are used in fire extinguishers), chlorofluorocarbons (which specifically contain chlorine) and any other substances that harm the ozone.
The destruction of ozone
References:
Chiras, Daniel D. (1998). Environmental Science: A systems Approach to Sustainable Development. Belmont: Wadsworth Publishing, fifth edition (381-387).
Bernstein, L., Winkler, A., & Zierdt-Warshaw. (1996).Environmental Science: Ecology and Human Impact. New York: Addison-Wesley, second edition (364-365).
http://earthobservatory.nasa.gov/Features/Ozone/
http://ozone.unep.org/Assessment_Panels/EEAP/eeap-report2006-FAQ.pdf
http://www.epa.gov/ozone/science/sc_fact.html
http://www.ec.gc.ca/ozone/docs/UO/faq/EN/faq.cfm