Because of its location,
- Climate change scenarios indicate the possibility of more serious riverflooding (larger predicted peak discharges), affecting mainly central and north-eastern
- Water shortages (as well as acute moisture stress) will affect western
- Climate change will cause an increase in salinity in the already affected soils in the coastal regions, which will impact the fragile ecological system of the Sundarbans. Local farmers are left with no alternative than to begin raising shrimp where they once grew crops. (1)
- Indirectly, climate change will aggravate health conditions, poverty etc. (3),(6)
(1) Agrawala, S., e.a., Development and climate change in
(2) Alam M., e.a., Impacts, vulnerability and adaptation to climate change in
(3) Brouwer, R., e.a., “Socioeconomic vulnerability and adaptation to environmental risk: A case study of climate change and flooding in
(4) Huq. S., e.a., Vulnerability and Adaptation to Climate Change for Bangladesh, Kluwer Academic Publishers,
(5) Monrirul Quader Mirza, M., e.a., "The implications of climate change on floods of the Ganges, Brahmaputra and Meghna rivers in Bangladesh Climatic Change", in: Climatic Change, 2003 (57) 3, pp. 287-318.
(6) Nelson, D.I., e.a., “Health impact assessment of climate change in
(7) USAID (United States Agency for International Development), Environmental Mapping and Workbook for
Der Spiegel Online, Photo Gallery: Prawns in the rice field, <http://www.spiegel.de/fotostrecke/0,5538,21321,00.html/> (accessed 12 February 2008).
Sustainable Development Networking Programme
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GLOBAL CLIMATE-CHANGES AND
SOME OF THEIR AFFECTS
ON THE SOUTH-WESTERN REGION
OF BANGLADESH
INTRODUCTION :
The universe and the Solar family behaves in ways some of which are still unknown to the scientists. At times we notice changes and at times altogether new phenomenon to take place in the nature. Whenever any deviation seems harmful we become frightened. In the recent decades, two such phenomena have endangered the lives and properties of people of the South-Western region of Bangladesh. These are : (i) Cyclonic storm, (ii) Tidal bore (due to cyclone or Tsunami) and (ii) Sea level rise. In this article we shall discuss global climate changes with their reasons and their effects on Khulna region of Bangladesh
MAJOR AIR-WATER RELATED DISASTERS IN BANGLADESH :
The major types of climatic and geotectonic hazards the people of South-Western region of Bangladesh suffer from are : (01) Cyclone, (02) Flood and (03) Tidal bore due to cyclone. The two new additions in this list are : (04) Tidal bore due to Tsunami and (05) Sea-level rise.
(01) Cyclone : Fig. 01 (Sarma ’96) shows the traversing paths of some of the major cyclones along with their directions and the affected Upazillas. After studying theses paths it is possible to arrive at the zones with High. Medium and fewer probabilities. This has been shown in Fig. 02 (Sarma ’96). The recent cyclones have not been incorporated in this figure.
(02) Flood : The natural flood zones (flood plains) of Bangladesh have been shown in Fig. 03 (Sarma ’96).
(03) Tidal Bore : The regions adjacent to the sea is prone to Tidal Bore. Fig. No. 4 (Sarma ’96) shows the Tidal prone areas of Bangladesh.
(04) Sea-level rise : This is a comparatively new phenomenon. The land mass of the country has got a natural slope towards the sea. The average height of Khulna from the mean sea level is only 1.83 Meters. If the level rises the low-lying areas will be submerged permanently. The darkened areas shown in Fig. No. 04 would be affected due to such rise.
From the above figures it may be seen that the worst affected area due to (i) Cyclone originating in the Bay of Bengal, (ii) Tidal bore and (iii) Sea-level rise will be the South-Western region of the country.
GLOBAL CLIMATE-CHANGES :
Climate is not any instant affair, it is the average of weather-related information of any place for a long time of say 20 to 30 years. Also the climate of various regions, countries and even places of this earth widely vary. For this reason it is quite difficult to identify to identify any significant change in climate. In the recent days however, men do increasingly feel two things, (i) Warming and (ii) Dimming. Thus the people of cool countries like U.K., Germany, Poland etc. complain of excessive hot in the summer, longer summer and shorter winter etc. Also sub-Saharan countries of Africa suffer from less rains etc. In Bangladesh people complain of less winter and longer summer season. Investigations prove that the reason for these are (a) Global Warming and (b) Global Dimming.
(a) GLOBAL WARMING : At one time the earth was as hot as the sun. Ever since it has cooled down and is still following that process. The sun is losing heat with time. The distance between the Sun and the earth is on slow increase. These three factors demand for a cooler earth. Global warming seems quite contradictory to this natural phenomenon.
(Some statistics : (i) The Sun produces energy in spectrum range of 290 nm to 2300 nm. Nm = nanometer = 109. The value of solar radiation is taken to be 100 lumens/watt, which is capable of producing intensity of 100 000 lux per Kilowatt per square meter.
(ii) The intensity of solar radiation that reaches the upper surface of the atmosphere is known as “Solar Constant” and is taken to be 1395 Watt per square Meter. This energy varies at the rate of +/- 2% due to variation of output of the sun and +/- 3.5% due to the variation distances between Aphelion and Perihelion.
(iii) Of the 100% solar constant arriving at the top of the atmosphere, 20% is reflected back from the cloud, 5% is reflected from the ground and 25% is diffused in the atmosphere. The remaining 50%, 23% diffuse and falls on the ground and 27% fall directly on the ground).
Even though called global warming, the warming in fact happens near the surface of the earth. It happens so, because the (i) radiating heat from the core of the earth, (ii) the reflected heat energy from the sun and (iii) the heat produced due to human activities cannot escape to the outer space because of the formation of a layer around the earth’s atmosphere. The modified layer of gas is constituted of Ammonia, Hydrogen Sulfide, Oxides of Sulfur and Nitrogen, Oxides and other pollutants produced by industrial plants and motor vehicles, Ozone, atmospheric Carbon Di-Oxide, Methane, Chloro-Fluoro Carbon (CFC) etc. Since these gases serve the same purpose the glass serve in a ‘green house’ these are called the green-house gas.
(b) GLOBAL DIMMING : Tons of minute solid particles from the industries, cities, vehicles, jet planes etc. escape upward. The affect created by the exhaust of the jet planes is known as Con-tail affect. When the solid particles come in contact with cloud the water particles of the cloud sticks to them and make the cloud impenetrable to Sunray. This thick or black cloud creates the following phenomenon :
(i) The sun’s radiation cannot reach the earth. It creates less light or ‘dimming’ and cooler environment.
(ii) The thick cloud retards escape of heat from the earth’s surface.
(iii) The thick layer of cloud reduces evaporation of water, because the sun’s ray cannot reach in contact with water below. As a consequence there happens less evaporation and less rain. This phenomenon causes more water to stay in the sea.
AFFECTS OF GLOBAL CLIMATE-CHANGES :
In short the affects of global warming and dimming are the following :
(i) Increase of temperature throughout the globe due to warming of the atmosphere under the modified layer of gas.
(ii) Lowering of temperature (and light) in the areas under dimming due to black cloud.
(iii) Less evaporation of water from the earth.
The following phenomenon is taking place due to the above mentioned warming and dimming : (a) Ice in the polar regions, ice berg, glacier, ice-cap of the mountains are melting, thus increasing water in the ocean and less flow of water in the rivers originating from the mountains. (b) Frozen ice under the soil in the regions near the pole is melting, thus reducing dry land. This is known as Perma-froze affect. (c) The cloud staying over Atlantic carries less water, causing less rains in the African countries.
WHO ARE TO BE BLAMED ?
At present lots of hue and cry are going on accusing the developed countries for production of green-house components in the form of exhaust from planes, cars and industries. Also the developed countries are accusing the rice producing and cow-raising Asian and African countries for production of Methane. While both the accusations are true, we shall endeavor to present a neutral picture of the problem here.
(01) The developed countries of North America, Europe and Australia produce vast quantity of green-house gas (Hydrogen Sulfide, Oxides of Sulfur, Oxides of Nitrogen, Carbon Di-Oxide, Chloro-Fluoro Carbon (CFC), Smoke, Carbon Mono-Oxide, dust particles etc.) from vehicles, domestic activities, Industries etc. Also the developing countries of Asia and Africa do the same by producing gases like Carbon Di-Oxide, Methane, Smoke, Carbon Mono-Oxide, Oxide, dust particles etc. in their water-logged rice fields, bogs and grass-eating cattle. Whatever might be the criticism or accusation, neither the developed countries can stop vehicles or industries, nor the developing countries can reduce rice cultivation or using cattle.
(02) Everyday millions of tons of green grass and plants are emptied by the rivers in the sea. These plants and the sea-weeds grown in the sea finally deposit on the bottom. These produce huge quantity of Methane, which are released in the nature. There is no one who can stop the sea from doing that.
(03) Considerable quantity of heat energy and gas from the earth’s core escape through the numerous volcanoes and under-water creeks. There is no practical way to stop those.
In such a situation, accusing one country by another or claiming compensation for such is an erroneous practice. The truth is, there is no practical way to stop the emission of green-house gas from various sources. Above the modified layer of gas there is cool air and above that extremely outer surface. The scientists can better take up programs regarding how to make the heat escape through this layer.
AFFECTS OF CLIMATE-CHANGES IN KHULNA REGION :
The scientists widely vary in their predictions about the rate of rise of water. Some sources say, there would be 3 meter rise within one decade, others say this rise would take place after 9 decades. The second prediction says a rise of 1 meter in 30 years. From what we have learn above we can say, the Khulna religion will be affected by global warming (and dimming) in the following ways :
(a) If the prediction of one meter rise in 30 years is taken to be true, then entire Khulna region extending up to Chandpur would be submerged after 30 years.
(b) The rivers carrying sweet water may be seen to carry excessive water in the rainy season and less during other seasons.
CONCLUSION :
We do not know what the international bodies or the scientists would do to fight back the ill affects of climate change. The reality is, they may not even find out any affective solution. In such a situation, each and every affected country needs to initiate their own programs to avoid the ill effects. We strongly feel that reclamation of land at the continental shelf is the ideal solution for Bangladesh. How that can be done is definitely the thought of the experts and scientists. We know in this age of science and technology the scientists have successfully done ‘near impossible’ projects. If they take up the project seriously, we believe they would come out successful. One Arab tycoon has created artificial island (Palm Beach Island) in the sea such that his creation could be seen from the moon. Our problem is no luxury, bit the question of life and death for millions. The Arab tycoon carried sand from the distant desert for earth fill. In our case the job is rather easy. By one estimate every year 400 billion Tons of silt comes to Bangladesh from India to Bangladesh through the major rivers. It has been discovered that major part of this silt escapes to the continental slope. We can save the lives and properties of millions only by trapping this escaping silt. Is it an impossible proposition in this age of science and technology ?
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References :
Sarma ’96 : CLIMATIC DESIGN MANUAL FOR BUILDING DESIGN IN BANGLADESH. Project submitted to Bangladesh University Grants Commission (Project Director : Bijon B. Sarma). June 1996.
*Sources of information of disasters : Paper Tropical Cyclones in Bangladesh. Md. Sazedur Rahman. Pp. 103-125. Report on the Technical Conference on Tropical Urban Climates. 28 March-2 April, 1995. WCASP – 30. WMO/TD No. 647, World Meteorological Organization.
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PROF. BIJON B. SARMA ARCHITECTURE DISCIPLINE, KHULNA UNIVERSITY
TERMS USED IN THIS PAPER :
CYCLONE : Cyclone or Lows is the term used to denote fast-moving wind towards an area of low atmospheric pressure. Normally it moves in a counterclockwise direction in the northern hemisphere and reverse, in the southern.
ANTICYCLONE : High-pressure area with clockwise winds is known as an anticyclone or Highs.
HURRICANE : Hurricane is the name given to violent storms originating in the Atlantic Ocean, Caribbean Sea, Gulf of Mexico, or North Pacific Ocean east of the International Date Line. Those taking on the west of the International Date Line are called typhoons.
Tropical cyclones, Hurricanes or Typhoons are caused due to heat (usually over 27 C, 80 F) from the water, where heat is caused by the sun ray or under-eater volcanoes.
TORNADO : Violently rotating column of air extending from ground to thundercloud level with an average diameter of about 50 m (160 ft) is known as Tornado.
TSUNAMI : A Tsunami is a series of vast waves with 100 to 200 km widths (the distance between one wave crest to the next), that may travel hundreds of kilometers across the ocean with velocity of 725 to 800 km/h. It may be insignificant (say, only about half a meter high) in deep sea, that grow in height as it enters shallow coastal waters. Tsunamis are usually caused due to displacement or rupture of the earth’s tectonic plates.
FLOOD : Flood is caused by superfluous water, which may happen due to excessive rain or inefficient drainage. Periodic or natural floods may occur seasonally in the depressed areas or flood plain. Flood caused by water suddenly by a number of river system is called a flash flood.
GLOBAL WARMING : It is the phenomenon of warming the atmosphere in the annular space in between the earth’s surface and the modified layer of gas, where the heat emitted by the earth is trapped.
GLOBAL DIMMING : It is the phenomenon of dimming of the earth below the cloud, darkened due to carbon particles, that result in less evaporation of sea water.
GREENHOUSE GAS : Water-vapor, Ammonia, Hydrogen Sulfide, Oxides of Sulfur and Nitrogen, Oxides and other pollutants produced by industrial plants and motor vehicles, Ozone, atmospheric Carbon Di-Oxide, Methane, Chloro-Fluoro Carbon (CFC) etc. are known as green house gas.
SOURCES OF GREEN HOUSE GAS : The major sources green house gases are the following :
(i) Industries : Hydrogen Sulfide, Oxides of Sulfur, Oxides of Nitrogen, Carbon Di-Oxide, Methane, Chloro-Fluoro Carbon (CFC), Smoke.
(ii) Vehicles, airplanes : Carbon Mono-Oxide, Carbon Di-Oxide, dust particles.
(iii) Water logged rice fields, bogs etc. : Ammonia, Methane.
(iv) Domestic cattle : Methane.
(v) Sea bed : Methane (generated from Sea weeds deposited on the bottom).
(vi) Nature : Water-vapor, Ozone.
CONTAIL AFFECT : The lowering of temperature and sunlight by the black layer of smoke released by the airplanes is known as con-tail affect. It lowers temperature and helps to decrease evaporation.
PERMA-FROZE : The water in the land in the cold regions get permanently frozen and act as solid land. Due to global warming, this soil releases water and the land vanishes into water body. This is known as Perma-froze affect.
CORIOLIS FORCE : The slippage of the air cover over the earth’s surface at the time of earth’s rotation is known as Coriolis force.
I request the students from Belgium and Netherlands to go through this article.
Prof. Bijon B. Sarema.
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