Bangladesh in global warming scenario
Today one of the most hotly deliberated topics on Earth is the issue of global warming or climate change. Increased populations, extreme demand for energy and limited resources have put the global environment under threat. As a result we are getting increasingly aware about the stake of environment we reside in. Nowadays the terms greenhouse effect, industrial pollution, air pollution, sustainable development, and biodiversity etc. have become frequently used words.
The greenhouse effect is a natural occurrence initiated by carbon dioxide and other gases in the atmosphere. Scientists all over the world have known for more than a century that greenhouse gases like carbon dioxide, methane, water vapour and chlorofluorocarbons help prevent heat from escaping the earth's atmosphere. In the temperate region green houses are built to cultivate crops when the outer land remains covered by snow. Sun light of a shorter wavelength enters the glass roof of the green house and strikes the soil and radiates back with a longer wave length. The change in wave length of sunlight transports the release of heat energy. This stored heat energy raises the green house temperature, making its environment suitable for crop growth though the outside temperature still remains around freezing point. Similarly, greenhouse gases also keep the earth warm enough to support life. So, the concern is not with the fact that we have a greenhouse effect, but whether human activities are leading to an enhancement of the greenhouse effect or causing the global warming.
Automobiles and other transport exhausts are thought to be the principal source of atmospheric carbon dioxide. Coal or petroleum based power plants and different industries release a huge amount of carbon dioxide into the atmosphere. In addition, animal breathing, plant and microbial respiration, agricultural and other solid waste disposal also produce a large amount of carbon dioxide. This carbon dioxide is dissolved into ocean water, incorporated in marine organism and utilised by green plant and so on.
On the other hand, deforestation may have terrible global effects as well. Forests are natural consumers of carbon dioxide -- one of the greenhouse gases whose buildup in the atmosphere contributes to global warming. Annihilation of forest not only removes these carbon sinks, but forest burning and decomposition pump into the atmosphere even more carbon dioxide, along with other greenhouse gases. Increase of carbon dioxide in the lower levels of the atmosphere warm sit-up and global warming obviously takes place. The global climate models predict that a doubling of carbon dioxide concentration will increase the mean daily temperature by about two ( to five degree centigrade. There are likely to be more natural calamities like devastating hurricanes, tornedos, cyclones, storms and drought. Altered weather will greatly harm the world's largest food source or agricultural pattern.
Indirect indicators of warming such as borehole temperatures, snow cover, and glacier recession data are in significant agreement with the more direct indicators of recent warmth. Evidence such as changes in glacier length is useful since it provides qualitative support for existing meteorological data. However, there is a great deal of disagreement among scientists about whether global warming is actually occurring and it is certainly an important political issue which has shaped legislation and generated regulations.
According to Special Report on Emission Scenarios (SRES) published by Intergovernmental Panel on Climate Change (IPCC), due to thermal expansion and loss of mass from glaciers and ice caps, global mean sea level is projected to rise by 0.09 to 0.88 meters between 1990 and 3100. Over several centuries, it may be possible to observe the effect of these orbital parameters, however for the prediction of climate change in the 21st century, these changes will be far less important than radiative forcing from greenhouse gases. Further research is required to improve the ability to detect, attribute and understand climate change, to reduce uncertainties and to project future climate changes. In particular, there is a need for additional systematic and sustained observations, modeling and process studies.
In the 1970s, various sectors of the scientific community became concerned about the possible reduction in the ozone layer surrounding the earth in the upper atmosphere. After a decade like in 1980s, scientists, governments, and the public in all over the world became concerned about the possibility that the world may be getting warmer. However, there is much need to refine our understanding of key natural forcing mechanisms of the climate, including solar irradiance changes, in order to reduce uncertainty in our projections of future weather pattern change.
As it relates to recent estimate by Intergovernmental Panel on Climate Change (IPCC), due to global warming the sea level may levitate by about 20 centimeter by 2030 and it could be as much as one meter by the end of the next century depending upon the future control of green house gases.
Based on the geographical structure like low elevation of the land areas, the low inclining of the rivers, and proximate to the sea, Bangladesh is one of the most susceptible country to the effects of sea level rise and climate change. In coastal area, the significant effects of sea level changes on flooding, drainage, agriculture, tides, waves and vital wetlands cannot be overlooked. One (1) meter sea level rise will inundate about 5,608 million acres of existing coastal land which is about 15 percent of the total area of Bangladesh. The area comprising of 65 percent of greater Khulna, 99 percent of Barisal, 100 percent of Patuakhali, 44 percent of Noakhali and 12 percent of Faridpur will be inundated and as a result 13.74 percent of net cropped area and about 401,600 hectares of mangrove forest along with its wild life will be vanished.
A very rough appraisal indicates that with one meter sea level rise, area of high salinity intrusion will increase from existing 13 percent to 31 percent of Bangladesh land area. In fact, entire south and south western part of Gages, Padma-Lower and Megna river system will be affected by high salinity penetration. This will reduce the crop yield significantly in the affected areas. Salinity intrusion may affect the power station's water use in the Siddhirganj and Narayanganj areas.
It is patent that the green house effect is a great threat for the world. The industrialised countries are mostly responsible for this undesirable effect. The use of chlorofluorocarbons in air conditioners, refrigerators, and as propellants has resulted in the release of large amounts into the atmosphere. Because chlorofluorocarbons are implicated in both global warming and ozone depletion, considerable international attention is focused on controlling their manufacture and release.
Cutting across these uses is a crucial need associated with strengthening international co-operation in order to better utilise scientific, computational and observational resources. This should also promote free exchange of data among scientists. A special need is for increasing the observational and research capacities in many regions, particularly in developing countries. Finally, as is the goal of this assessment, there is a continuing imperative to communicate research advances in terms that are relevant to decision making.
Global warming may be reduced by three inter linked levels such as personal, technological and legal. The levels should work by energy conservation, shifting to renewable energy sources, reforestation and educating people to make them aware about global warming. At the personal level, recycling, increasing efficiency and reducing demands for every item are parts of conservation strategy. Use of renewable energy sources like solar and wind energy should be enhanced. Improvement of energy efficiency of all machinery, buildings and factories will reduce the rate of carbon dioxide emission. Replacement of fossil fuels by solar energy, biofuels (ethanol) hydropower, hydrogen fuel, wind etc. will reduce the carbon dioxide emissions.
It is an obvious indication in modern science that we will be living with global warming for the rest of our lives. Thus, it is indispensable to think ahead and take all essential steps in time to minimise the greenhouse emissions all over the world otherwise soon it will be too late. Finally, control of the green house gas is the crying need for maintaining an environmental equilibrium and saving the world for the future generations.
Shalim Uddin is a Research Scientist in the USA
E-mail: [email protected]
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