“Do sunscreens matter?” KEVS THESE R JUST HEADLINES TAKEN FROM THE INTERNET SITE www.environment.about.com
These controversial headlines which seemingly keep coming has sent the world into a frenzy of inexorable curiosity. So what is ozone depletion? What are its causes and the effects on human life?
The Earth's atmosphere is divided into several layers. Most atmospheric ozone is concentrated in a layer in the stratosphere, about 15-30 kilometers above the Earth's surface. The ozone layer absorbs a portion of the radiation from the sun, preventing it from reaching the planet's surface. Most importantly, it absorbs the portion of ultraviolet light called UVB (ultra violet radiations). UVB has been linked to many harmful effects, including various types of skin cancer, harm to some crops, certain materials, and some forms of marine life. Laboratory and epidemiological studies demonstrate that UVB causes nonmelanoma skin cancer and plays a major role in malignant melanoma development. In addition, UVB has been linked to cataracts. All sunlight contains some UVB, even with normal ozone levels. It is always important to limit exposure to the sun. However, ozone depletion will increase the amount of UVB, which will then increase the risk of health effects. During the past two decades, governments around the world have waged massive public relations campaigns to raise public awareness of the need to take adequate protection from the sun such as wearing sunscreens, hats, and protective clothing Moreover when gases such as chlorofluorocarbons (CFS) used as refrigerants, solvents and foam blowing agents, Halons, extremely effective fire extinguishing agents, and methyl bromide, an effective produce and soil fumigant, containing bromine are transported by winds into the stratosphere, they cause damage to the protective ozone layer. Like I mentioned above an adequate example is the ozone hole over Antartica . The activation of chemicals such as chlorine and bromine leads to rapid ozone loss, which then results in the Antarctic ozone hole . Large volcanic eruptions can also have an indirect effect on ozone levels. In addition, research has shown that ozone depletion occurs over the latitudes that include North America, Europe, Asia, and much of Africa, Australia, and South America. Thus, ozone depletion is a global issue. Reductions in ozone levels will lead to higher levels of UVB reaching the Earth's surface. The sun's output of UVB does not change; rather, less ozone means less protection, and hence more UVB reaches the Earth. Studies have shown that in the Antarctic, the amount of UVB measured at the surface can double during the annual ozone hole. Another study confirmed the relationship between reduced ozone and increased UVB levels in Canada during the past several years. However there are various measures, which have been taken up in order to try and prevent depletion of the ozone layer. A few such are as follows. In 1992, reacting to the latest scientific assessment of ozone layer, the Parties decided to completely end production of halons by the beginning of 1994 and of CFCs by the beginning of 1996 in developed countries. By November 1992, several major parties had decided unilaterally to accelerate phase out of ozone depleting substances beyond that stipulated in the London amendments to the Montreal Protocol. Germany and Switzerland banned CFCs and other ozone depleting substances by the beginning of 1995. President Bush ordered a U.S. phase out by the end of 1995. Following these initiatives, and based on available scientific, environmental, technical, and economic information, the Conference of Parties at Copenhagen accelerated the phase out schedules for CFCs, methyl chloroform, and carbon tetrachloride to January 1, 1996. These measures are a very encouraging sight as it is very necessary that we realize the vast amount of destruction, which awaits us before we are swept under our feet by the large holocaust in the form of ozone depletion.
Another issue which has invariably come to our knowledge & which has caused great concerns amongst researchers is climate change which has had drastic consequences resulting in global warming. Scientists working on climate change research face various theoretical challenges. Theoretically, anthropogenic theories of climate change were matched by theories of natural climate change. One commonly discussed theory falling in the nature induced school of climte change hypothesizes that volcanic erruptions and their effects on atmospheric conditions better acconts for climate variability.
Climate change science also builds on a very simple theory. anthropogenic (human) caused emissions of greenhouse gasses contributes to a layer of gasses around earth's atmosphere that blocks some of earth's emanating heat from escaping to space, causing a general heating or global warming pattern. Scientists have identified six primary greenhouse gases. They are carbon dioxide , methane , nitrous oxide , hydroflurocarbons , perflourocarbons and sulphur hexaflouride. In addition, water vapor is also a powerful greenhouse gas, but its concentration depends mainly on evaporation and rainfall, not on human activity. All these constituents are distributed in the atmosphere from the surface to high altitude These gases in the atmosphere maintain the Earth's temperature at the average level by trapping some of the infrared radiatons emitted by the earth’s surface. This trapped infrared energy heats both the atmosphere and the surface and maintains the mean global temperature of the Earth at a "warm" 59° F (or 15° C). Without these greenhouse gases, all the infrared radiation would be lost to space, and the Earth's global temperature would be near 0° F (or -18° C), a very inhospitable environment. Therefore without the blanket of the atmosphere including the greenhouse gases, the day side of the earth would be hot and the night side very cold like a desert or the Moon.
However these gases also tend to act as atmospheric road blocks. Scientists call this road blocking ability the Global Warming Potential (GWP) of a gas. In terms of climate change power, these engineered chemicals are the most climate warming inducing. Moreover with the heavy use of fossils fuels in the 20th century , atmospheric concentrations of carbon dioxide has risen dramatically resulting in an invariable increase in temperature for example plants absorb the gas as they grow, trapping it until they die and decay. So reduction of forests and other agricultural practices by humans may change the absorption of carbon dioxide . Because of this global temperatures are expected to rise from 1 degree to 3.5 degree by the year 2100 . although this trend appears to be a small change , the increase would make the earth warmer than it has been in the last 125,000 years , possibly changing climatic patterns , affecting crop production , disrupting wildlife distribution and raising the sea level.
Our continuous ignorance about the hazards of misuse of nature’s products have brought us to this stage where one cannot even live up to the average life span of an individual. Although climatic change is ruled by various factors this intrinsically self indulgent world filled with the utmost complicated individuals have increased these hazards to such an extent that one is intoxicated in this web of deterioration!!! Unless there’s something done to change our lifestyle , life itself will become only a statement and mankind will soon disappear too!