Our environment today is facing a number of problems. All those problems are causing dangers to take shape against the existence of the whole biosphere of this planet. But who is behind all those problems? The answer is – M A N.
All those problems have become great topics for discussion, planning and implementation in the world on different levels.
An important topic that people discuss or argue about is called as an issue. We have different types of environmental issues at local, regional, national and global levels. Here, we are going to discuss about some global issues like Green House Effect and Global Warming, Climate Change, Acid Rain and Depletion of Ozone Layer. These are global issues caused due to human activities in their own countries but these issues relate to the fate of the whole planet.
GREEN HOUSE EFFECT
The warming effect produced inside a greenhouse by its glass panels, is called as Green House Effect. A green house is a specialized house constructed at horticulture stations for keeping plants that survive better in warm surrounding.
Green House Effect: How does it occur?
The walls or panels of a greenhouse are made of specialized glass that allows short wave solar radiations to go inside but does not allow long wave infrared heat energy of the glass house to pass out. In fact, some of the solar radiations that are absorbed inside the greenhouse get transformed into heat energy in the form of long wave infrared radiations that cannot go out of the glass panels of the green house. Thus, temperature inside the greenhouse rises as compared to the temperature outside. The term- Green House Effect was coined by J. Fourier in 1827.
Green House Gases (GHGs)
Gases that help in causing greenhouse effect are called as greenhouse gases (GHGs). These gases either occur naturally or are produced on earth due to human activities of burning fossil fuel and bio-mass.
One of the most abundant naturally occurring greenhouse gases is the water vapour. Other greenhouse gases are carbon dioxide, methane, Nitrous oxide, Trifluoromethyl sulphur pentafluoride and hydrochlorofluorocarbons. It is since 1700s, that a substantial increase in the concentration of greenhouse gases has occurred in the atmosphere.
1. Water Vapour: It accounts for about 60 to 70 percent of the natural greenhouse effect. Its level in the atmosphere rises with the increasing global warming adding up further to the greenhouse effect.
2. Carbon dioxide: It is released into atmosphere through decay or burning of organic substances and through volcanic eruptions. It circulates in the atmosphere through carbon cycle. A good part of carbon dioxide is utilized through photosynthesis and major part of it is absorbed by oceans, rivers and lakes. But, in the modern age of industrialization and increasing automobile exhausts the concentration of carbon dioxide is increasing faster than the earth’s natural capacity of assimilation. It has been assessed that the level of CO2 in the atmosphere has risen by more than 30 percent since 1750.Currently, the CO2 concentration in the atmosphere is about 370 parts per million (ppm). It accounts for more than 60 percent of the additional greenhouse effect.
3. Methane: This gas is produced through various sources like decomposing organic substances, coal mining, production and transport of other fossil fuels etc. Its concentration in the atmosphere has become more than double since 1750. Scientists are of the opinion that it is an extremely effective heat trapping gas. One molecule of methane is 20 times more efficient in terms of trapping infrared radiation than a molecule of carbon dioxide.
4. Nitrous Oxide: This gas is released into the atmosphere by burning of fossil fuels, automobile exhaust, decomposition of nitrogenous fertilizers in the soil etc. Its level in the atmosphere has risen by 17 percent since 1750.This gas has a capacity of trapping heat 300 times more effectively than carbon dioxide. It can stay in the atmosphere for about 100 years.
5. Fluorinated Compounds: Compounds comprising CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons) and HFCs (hydrofluorocarbons) are man- made compounds called as fluorinated compounds. These compounds are used in a variety of manufacturing processes. Each molecule of these synthetic compounds is many thousand times more effective in trapping infrared radiations than a single molecule of carbon dioxide.
CFCs were first synthesized in 1928. Since then, these were widely used in the manufacture of aerosol sprays, blowing agents for foams, packing materials, as solvents and as refrigerants. By 1992 an amendment in the Montreal Protocol was made to ban these compounds worldwide. However, the HFCs compounds do not contain chlorine and stay in the atmosphere only for a short time. Hence, these are regarded as safe for various applications.
6. Trifluoromethyl sulphur pentafluoride: This compound was not reported before 2000. Each molecule of this industrially produced compound can trap heat more effectively than all the other gases known to cause greenhouse effect.
Importance of Green House Effect
Our Earth is subjected to greenhouse effect which is very important for creating a climate favourable to the sustenance of most forms of life on it. In this context, the greenhouse effect can be defined as –
The effect of warming and insulation of the earth produced due to some heat trapping gases accumulated in the atmosphere after their emission from the earth surface, is called as greenhouse effect.
The natural greenhouse effect is in fact, a process of thermal blanketing of the earth which maintains its temperature around 33 Celsius degrees which helps in the sustenance of life on it. Without the greenhouse effect, the climate of the earth is reported to become too cold for most of the life to survive. Then, the temperature may fall much below the required level essential for the existence of life. Hence greenhouse effect is an important natural process which is essential for the survival of life on this planet.
Green House Effect and Global Warming
Human activities of pollution are modifying the natural process of greenhouse effect. The advent of the Industrial Revolution in the 1700s boosted up the activities of burning of fossil fuels like coal, oil and natural gas which released lots of heat absorbing gases into the atmosphere. Clearing of land for agriculture or for urban settlements wiped out the vegetation that acted as ecological sink for some of those gases like carbon dioxide. These heat absorbing gases accumulate in high concentrations in the upper atmosphere around the earth extending up to 100 km above its surface and act as glass panels of a green house. They allow much of the short-wave solar radiation to reach to the earth surface but stop much of the long wave infrared rays against escaping out as heat. They absorb these infrared radiations and then re-radiate most of them back to the earth surface. Thus, the temperature of the atmosphere rises gradually causing an unnatural heating effect which is called as the Global Warming. The Global Warming is the enhanced greenhouse effect due to greater accumulation of GHGs in the upper atmosphere.
The warming of the earth’s atmosphere attributed to a build-up of greenhouse gases in high concentration in the atmosphere is called as the Global Warming.
Global Warming is a term which is used to refer to the observed increase in the average temperature of the earth’s atmosphere and oceans in recent decades. Scientific discoveries reveal that the world experienced warmest atmosphere during last 50 years out of the period of 100 years. The global mean temperature increased by about 0.5 to 1 degree Celsius, within a period of last 100 years.
Global Warming and Climate Change
The regular pattern of weather conditions of a particular place is called as climate of that place. This regular pattern of weather conditions is considerably disturbed by fluctuations in temperature. The disturbance in the pattern of weather conditions at a particular place may rightly be called as Climate Change.
The Global Warming itself is not the Climate Change as the effects of global warming may not be uniformly negative. But it is the abnormal rise in global temperature that is causing changes in the global climate. Let us see, how abnormal changes in temperature may lead to climate change.
Temperature has significant role in the regulation of water cycle in the environment. Hence, rise in global temperature can change the pattern of water cycle. On the other hand, increased temperature can cause most of the ice to melt down. The increased evaporation of water due to high temperature may alter the pattern of cloud formation and rains at different places. The physical features of the earth also play important roles in causing temperature variations that finally result into variations in air pressures. These variations cause disastrous conditions like storms, cyclones, tornadoes and hurricanes etc.
International agencies studying the climate change have projected the globally averaged temperature to increase by 1.4 to 5.8 degrees Celsius over the period 1990 to 2100. The Intergovernmental Panel on Climate Change (IPCC) does important climatic researches and surveys on periodic basis. It has hundreds of scientists from many different countries that study and analyse the meteorological changes and provide a collective picture of global warming and other changes in the climate systems. The Third Assessment Report of IPCC was released in January 2001.
According to the reports of Asia-Least Cost Green House Gas Abatement Strategy (ALGAS) Project, the energy sector is the largest contributor of GHG (55%) in India. The ALGAS Project in India is funded by the Asian Development Bank, Global Environmental Facility (GEF) and United Nations Environmental Programme (UNEP).
Impact of Global Warming
The Global Warming has various types of impacts on the whole earth and its systems. Some of the major impacts of Global Warming are mentioned below.
1. Global Warming may cause frequent natural disasters like cyclones, storms and hurricanes, floods and droughts. It may also cause cloud bursts, avalanches, landslides, mud- flows and earthquakes.
2. Global Warming is causing melting of ice and glaciers which is leading to a rise in sea- level. As a result, the creeping up of oceans swallow low lying islands and coastal areas.
The rising sea level is causing loss of land, loss of property and loss of lives. It may also cause large scale displacement of people which may further create a problem of rehabilitation.
3. It is damaging forests, agriculture and water supplies.
4. It is damaging various ecosystems like mangrove- swamps, coral reefs and coastal lagoons etc. due to various reasons like reduction in pH of oceanic water and increasing deposits of acids.
5. Some populations of migratory birds have been declining because of unfavourable variations in climatic conditions. On the other hand, the migration time of spring butterflies in Britain has become earlier than it was 30 years ago. It has been observed that the behaviours of some bird species have changed due to climatic variations in the Indian state of Orissa. Some birds like Black Headed Oriole and Open Billed Stork have changed their times of migration where as some birds like Bronze Winged Jacana and Indian Small Skylark have changed their nesting behaviours.
6. The change in climate due to rise in global temperature is causing migration of species of wild animals towards poles and high altitudes. Since those areas are already inhabited by animals of different species, the migrated species receive the status of Refugee Species.
Prevention and Control of Global Warming
The Global Warming can be prevented and controlled by following important measures-
1. Reduction on the consumption of fossil fuels by depending on non- conventional renewable sources of energy like wind, sunlight, nuclear and bio- energy.
2. Checking the GHGs at the source of their production and disposing them elsewhere.
3. Collection or recovery of GHGs already present in the atmosphere and their disposal.
4. Learning to adopt and accept the changes in the climate.
5. International co-operation for reduction of GHGs emission with full majority.
Global Efforts
Periodic Surveys, researches and assessments have proved that the global warming causing changes in the world climates is increasing day by day. It is currently recognized as an important global issue. Representatives from over 160 countries have met regularly to discuss ways to reduce GHG emission. In 1997 a conference was organized in Kyōto, Japan, in which world nations signed an agreement called as Kyōto Protocol. According to the Protocol, the industrialized nations were required to cut their GHG emissions to an average of 5 percent below 1990 levels, by 2012. Russia’s cabinet approved the treaty in 2004 and paved the way to start it with effect from 2005. The protocol has been ratified by more than 126 countries. But Australia and U.S. did not support the protocol.
In early December 2005, representatives from 90 countries met in Montreal, Canada, to discuss ways on cutting down the use of fossil fuels so as to ensure less emission of carbon dioxide. According to the Montreal bulletins, the CO2 level in the atmosphere is now higher within past 650,000 years. Unfortunately, the two biggest CO2 emitters of the world – Australia and United States refused to cut down their emissions.
Image courtesy: wickipedia
