Some information for those who may not know much about
causes and implications of “Greenhouse Effect” For those of you who have been living under a rock or asleep for last 20 years or those who want to know more about it, here is a brief article.•The Greenhouse Effect maybe most important natural phenomena and may lead to major changes in our lifestyles within our lifetime.
Today, whenever there is a natural disaster, Greenhouse Effect seems to be on agenda. It wasn’t so long ago that scientists were dismissive of Greenhouse Effect and there are some still that do not believe it exists, just like there are still people out there that think world is still flat and Holocaust never existed. So what is Greenhouse Effect? What is Greenhouse Effect? The Greenhouse Effect is culmination of various Greenhouse gases that have been trapped in Earth’s stratosphere that is leading to changing of word’s climate. •Under influence of sun’s rays, earth’s temperature varies from 0 to about 50oC with an average through night and day, winter and summer, of about 15o C •The warming is done by rays from sun, including very shortest, ultraviolet (UV) rays and longest infra-red (IR) rays which give you that warm feeling when you walk out into sunshine, much like an electric radiator warms you when you turn it on and get close to it. •Some of incoming rays are reflected back by clouds in sky and others by sea and land, particularly deserts and snowfields. •Not all those reflected rays go back into space, instead, atmosphere re-radiates many of IR rays towards earth making it warmer still. It is this ability of atmosphere to re-radiate warm rays which creates Greenhouse Effect. •Water vapour, carbon dioxide and certain other trace gases, absorb some of this radiation and prevent it being sent back into space. This “blanket effect” keeps earth warm. History of Greenhouse Effect It is not a new phenomena or concept. The term “Greenhouse gas” was first used in Nineteen Century, by Irish born scientist John Tyndall in a paper he wrote in London’s Philosophical Magazine in 1863. It wasn’t until 1960’s that Professor Bert Bolin of Stockholm University worked on phenomenon. When he discussed it with fellow scientists they said “This is science fiction. We don’t believe it”. However by mid 1970’s things were starting to change rapidly as scientists were starting to accept he was right. How do we know Greenhouse Effect exists? What is evidence? 1.Scientists have analysed climates on planets like Venus and our moon. Venus which is covered by a very dense atmosphere of carbon dioxide. Its surface temperature is around 500o C. Whilst moon which has no atmosphere has an average temperature of approximately -18oC. Our atmosphere keeps surface of our earth, with an average of 15o C, some 33o C warmer and thus habitable.
2.Evidence of ice cores Over past 160,000 years carbon dioxide and methane levels trapped in ice cores have varied with global temperature. Scientists have been able to drill out ice cores from Arctic and Antarctic and measure levels of carbon dioxide and methane.
3.Increase in surface temperature of approximately 0.5oC over 100 years as carbon dioxide levels increase Studies conducted by scientists have concluded that earth’s temperature remained fairly constant until start of Industrial Revolution. Indeed it did not change much until start of twentieth century.
•From 1880 to 1940 there was a warming of just a quarter of a degree. Most of it was lost between 1940 and 1970. •From 1950 to 1980 average surface temperature was 15oC. •Between 1970 and 1980 temperature average went up by three-tenths of a degree C. •1987 and 1988 were warmest years on record
4.Sea levels are rising and small glaciers are melting Scientists using satellite and imaging technology have been able to monitor melting of polar ice caps and glaciers. What are results of Greenhouse Effect By using very sophisticated computer modeling, scientists have been able to predict what world’s climate will be like when carbon dioxide levels have doubled. 1.Increase in world’s temperature It is thought that there will be an increase in average global temperature by between 1.5 and 4.5oC . •By year 2030 an increase of 2oC, by 2100 an increase of 6oC. The warming will be greater at higher latitudes and in winter. This will lead to melting of polar ice caps and glaciers which is already evident, in places like Greenland, Arctic and Antarctic. 2.Changes in World’s climate The Greenhouse Effect will lead to world-wide changes in weather and climate. Some places may get more rain and storms while other places may get less. Not all changes will be bad. However, almost everywhere in world will have changes in weather, which will have a big impact on our lives 3.Rising Sea Level It is estimated that by year 2030, average sea level will increase by approximately 20cms. This will be due mainly to melting of polar ice cap, but also warming of atmosphere will heat upper layers of oceans, which will expand when heated. For low lying countries in Pacific like Tuvalu and Kiribati, and in Indian Ocean like Maldives and other countries like Holland may altogether disappear. 4.Other impacts Other impacts could be dieing out of some species of animals and plants, such as coastal marine environments and coral reefs. Some plants would not be able to survive temperature increases. It takes thousands of years for forests to move north or south to cooler climates. According to Joel B. Smith, co-author of an EPA report states that “such a warming over a century would require forests to move five times faster than fastest rate recorded by paleontologists since end of last ice age”. What are primary Greenhouse gases? They are a number of organic compounds which have more than two bonds (i.e 3 atoms). The seven major Greenhouse gases are:
