Natural climates problems

BANGLADESH is widely known as a flood or natural disaster prone country for many years. In

recent times many European countries have also experienced floods. Once, United States was

free from natural calamities but not now. US people are also afraid with possible revisit of

hurricane Katrina. Environmental depletion and global warming are identified as the prime

reasons for worldwide natural disasters.

Flood hit Bangladesh in the past and also may hit in the future. But, the nature and duration of

flood are changing day by day. If heavy rainfall occurs in a year due to global warming,

floodwater inundates Bangladesh. On the other hand, if there is no rain or less rain in other year,

the irrigation is hampered and so is food production. The major floods those are flooded over

Bangladesh are:

In the 19th century, six major floods were recorded in 1842, 1858, 1871, 1875, 1885 and 1892.

Eighteen major floods occurred in the 20th century. Those of 1987, 1988 and 1951 were of

catastrophic consequence. More recent floods include 2004 and 2010.

The catastrophic flood of 1987 occurred throughout July and August and affected 57,300 km2 of

land, (about 40% of the total area of the country) and was estimated as a once in 30-70 year

event. The flood's main cause was the creation of Erranticophrus (top soil wash away reaction)

from the inhabitants of the Himalayas irrigating their mountains vertically. The seriously

affected regions were on the western side of the Brahmaputra, the area below the confluence of

the Ganges and the Brahmaputra and considerable areas north of Khulna.

The flood of 1988 occurred throughout August and September, which was also of catastrophic

consequence. The waters inundated about 82,000 km2 of land, (about 60% of the area) and its

return period was estimated at 50–100 years. Rainfall together with synchronisation of very high

flows of all the three major rivers of the country in only three days aggravated the flood. Dhaka,

the capital of Bangladesh, was severely affected. The flood lasted 15 to 20 days.

In 1998, over 75% of the total area of the country was flooded. It was similar to the catastrophic

flood of 1988 in terms of the extent of the flooding. A combination of heavy rainfall within and

outside the country and synchronization of peak flows of the major rivers contributed to the

river.

The 2004 flood was very similar to the 1988 and 1998 floods with two thirds of the country

under water.

Dozens of villages were inundated when rain pushed the rivers of northwestern Bangladesh over

their banks in early October 2005. The Moderate Resolution Imaging Spectroradiometer on

Terra satellite captured the top image of the flooded Ghaghara and Atrai Rivers on October 12,

2005. The deep blue of the rivers is spread across the countryside in the flood image.

Cyclones happened in the past and it is also happening now. Whether the nature of cyclones has

changed that is something scientists will be able to answer. But Bangladesh is only at the

receiving end when it comes to man-made disasters. We, the people of the world, are polluting

the sea, and the sea in return gives us Tsunami, we are drilling polar areas to explore minerals,

and melted ice of those areas are increasing the water level of the sea, which may even cause our

beloved country to sink in the sea in future. In here we can include the prime cyclones that was

happened in Bangladesh

3 November-13 November: The 1970 Bhola cyclone hit the entire coast of Bangladesh.

Most affected were Chittagong, Barguna, Khepupara, Patuakhali, and north of Char

Burhanuddin, Char Tazumuddin and south of Maijdi, Haringhata. Maximum windspeed

reached about 222 km/h. Maximum storm surge was about 10.6 m.

5–6 November 1971: A cyclone hit coastal areas of Chittagong.

28–30 November 1971: A cyclonic storm hit the coast near the Sundarbans. Maximum

wind speed was 97–113 km/h. The storm surge reached 1 m. Low lying areas of Khulna

town inundated.

6–9 December 1973: The coastal areas near the Sundarbans were hit by a cyclone,

accompanied by storm surge. Coastal areas near Patuakhali and nearby islands were

submerged under the tidal bore.

13–15 August 1974: A cyclonic storm hit Khulna. Maximum wind speed reached

80.5 km/h.

24–28 November 1974: A cyclone struck the coastal areas near Cox's Bazar and

Chittagong, including the offshore islands. Maximum wind speed reached 161 km/h. The

storm surge was up to 2.8-5.2 m.

9–12 May 1977: Khulna, Noakhali, Patuakhali, Barisal, Chittagong and offshore islands

were hit by a cyclone. Maximum wind speed was up to 112.63 km/h.

14–15 October 1983: A strong cyclone hit the coastal islands and chars near Chittagong

and Noakhali. Maximum wind speed reached 122 km/h.

5–9 November 1983: A cyclone hit Chittagong, Cox's Bazar coast near Kutubdia, St

Martin's Island, Teknaf, Ukhia, Moipong, Sonadia, Barisal, Patuakhali and Noakhali. The

maximum wind speed reached 136 km/h. The storm surge was 1.52 m.

24–25 May 1985: A severe cyclone hit Chittagong, Cox's Bazar, Noakhali and coastal

islands (Sandwip, Hatiya, and Urirchar). Maximum wind speed at Chittagong was

154 km/h, at Sandwip was 140 km/h, and at Cox's Bazar was 100 km/h. The storm surge

reached a height of 3.0-4.6 m.

8–9 November 1986: A severe cyclonic storm hit the coastal island and chars near

Chittagong, Barisal, Patuakhali and Noakhali. Maximum windspeed was 110 km/h at

Chittagong and 90 km/h at Khulna.

24–30 November 1988: A severe cyclonig storm struck Jessore, Kushtia, Faridpur and

coastal islands of Barisal and Khulna. The maximum windspeed was 162 km/h. The

storm was accompanied by a storm surge of 4.5 m at Mongla Port. Casualty: 5,708

people, and numerous wild animals at The Sundarbans (deer 15,000, Royal Bengal Tiger

9), cattle 65,000.

29–30 April 1991: The 1991 Bangladesh cyclone hit Bangladesh late 29 April night. The

storm originated in the Indian Ocean and reached the Bay of Bengal coast after 20 days.

The diameter of the storm was close to 600 km. The maximum wind speed (observed at

Sandwip) reached 225 km/h. At other places, the maximum wind speed was reported as

follows: Chittagong 160 km/h, Khepupara (Kalapara) 180 km/h, Kutubdia 180 km/h,

Cox's Bazar 185 km/h, and Bhola 178 km/h. (The NOAA-11 satellite estimated the

maximum wind speed to be about 240 km/h at 1.38 pm on 29 April). The storm made

landfall near the coast north of Chittagong port during the night of the 29th April. The

maximum storm surge height reached about 5 to 8 m. Casualty: 150,000 people, 70,000

cattle. Damages: loss of property was estimated at about Tk 60 billion.

31 May-2 June 1991: A cyclone hit the coastal islands and chars near Patuakhali, Barisal,

Noakhali and Chittagong. Maximum wind speed reachd 110 km/h. The storm surge was

1.9 m.

29 April-3 May 1994: A severe cyclonic storm hit the coastal islands near Cox's Bazar.

Maximum windspeed reached 210 km/h.

21–25 November 1995: A severe cyclonic storm hit the coastal islands near Cox's Bazar.

The maximum wind speed was up to 210 km/h.

16–19 May 1997: A severe cyclonic storm hit the coastal islands and chars near

Chittagong, Cox's Bazar, Noakhali and Bhola districts. The maximum wind speed was

225 km/hour, and the storm surge reached 3.05 metres.

25–27 September 1997: A severe cyclonic storm hit coastal islands near Chittagong,

Cox's Bazar, Noakhali and Bhola. It had wind speeds of up to 150 km/hour, and a storm

surge of 1.83 to 3.05 metres.

16–20 May 1998: A severe cyclonic storm with windspeed of 150 km/hour struck coastal

islands near Chittagong, Cox's Bazar, and Noakhali. The storm surge was from 1.83 to

2.44 metres.

19–22 November 1998: A cyclonic storm, with wind speeds up to 90 km/hour, and a

storm surge of 1.22 to 2.44 metres. Hit coastal islands and sand shoals near Khulna,

Barisal, and Patuakhali.

12-15 May 2007: Cyclone Akash struck about 115 km (70 mi) south of Chittagong in

Bangladesh.

November 15, 2007: Cyclone Sidr makes landfall on southern Bangladesh.

14-17 April, 2009: Cyclone Bijli; A relatively strong tropical cyclone, it caused extensive

damage in Moheskhali, Cox’s Bazar and Chittagong.

23-26 May, 2009: Cyclone Aila; A relatively strong tropical cyclone, it caused extensive

damage in Bangladesh. Especially in Patuakhali, Noakhali, Chandpur.

Apart from natural calamities we are facing two other disasters in Bangladesh: (a) our

agricultural land is reducing, almost 1 percent per annum. As a result, we would not be able to

increase the production of food grains beyond the limits supported currently available by high

yield varieties, (b) the high growth of population is hindering all our development plans. If we

could control the population growth from the time of our independence, there would not be any

people below poverty level at this point in time.

We have always heard that manpower is an asset. However, it is only true when the ratio of land

and population is right. In recent days, birth control is again somehow neglected. If the NGOs

who are spending hefty amount against HIV/Aids could spend a fraction of that for birth control

measures, the benefits would have been greater.

Our economy has already suffered by two natural disasters, flood and cyclone. The consequences

of cyclone are even more severe than the floods. We could not arrange adequate shelter for

everybody. It is not also possible as we have so much of population in such a small country.

The amount of loss we have incurred due to such calamities is huge in monetary terms. However,

we cannot measure the loss of lives in monetary terms.

Bangladesh has demonstrated high degree of resilience to natural calamities over the years.

Three major impact of global warming on Bangladesh may be categorised as: climate change,

sea level change, and changes in the pattern of distribution and density of population.

Climatic change Using general circulation models (GCMs) of the climate system, scientists had

predicted a global change in temperature in the range of 1.5°C to 4.5°C with the doubling of

carbon dioxide in the atmosphere.

Over the past 100 years, temperature has increased by 0.5°C, but in the next 50 years, that is, by

2050 AD the temperature in Bangladesh is expected to rise by 1.5°-2.0°C. As temperature

increases on a global scale, the hydrologic cycle will intensify and the rate of evaporation is

expected to increase by 12%. This, in turn, will increase the level of precipitation globally. There

may be regional variations in the amount of precipitation, but Bangladesh will experience an

increase in rainfall. Climate models developed by IPCC indicate that Bangladesh may experience

10 to 15 percent more rainfall by 2030 AD. Bangladesh is visited by devastating floods quite

frequently. In the past two decades, extensive flooding had occurred in 1987, 1988 and 1998

leading to colossal damages to infrastructures and the destruction of standing crops. An increase

in rainfall will only worsen the situation.

Scientists also predict that global warming will increase the frequency and intensity of tropical

storms. A high surface temperature of over 27°C of the sea helps in the formation of cyclones.

Global warming will raise the sea surface temperature more than what it is now, thus increasing

the possibility of cyclone occurrences. Bangladesh has already been experiencing catastrophic

cyclones. The one that hit Bangladesh in 1991 claimed 150,000 lives and caused staggering

losses to livestock and property. A warmer climate, by increasing the frequency of natural

hazards such as floods and cyclones, will further aggravate such situations and negate the

development efforts of the country.

Sea level changes: The sea level changes constantly in every locality due to changes in tides,

atmospheric pressure and wind velocity. But long-term sea level changes occur only due to

changes in the global climate. Global warming will cause a thermal expansion of the seawater. A

rise in temperature will also melt the polar and alpine ice sheets. Since Bangladesh is deltaic,

vast areas of the country will be submerged with the rise of the sea level. How much of the

country will be lost to the sea will depend on the relative change in the sea level. As Bangladesh

is part of an active delta a huge load of sediments is brought down and deposited by the great

river systems of the Ganges, Brahmaputra and Meghna. This leads to elevation of land.

However, the weight of the huge load of Sediment results in compaction of the soil and land

subsidence. The sea floor is also rising because of deposition of sediments brought down by the

rivers. Subsidence and uplift of land may also occur from tectonic processes. A Taskforce report

predicts that for one metre rise in the sea level will lead to loss of about 22,889 sq km of land,

which is about 15.8% of the total area of Bangladesh.

Being a low-lying and densely populated country Bangladesh would be worst hit by any rise in

the sea level. Coastal areas will experience erosion and inundation due to intensification of tidal

action. A rise in seawater will enable saline water to intrude further inland during high tides.

Destruction of agricultural land and loss of sweet water fauna and flora could also occur. The

shoreline will retreat inland, causing changes in the coastal boundary and coastal configuration.

The process will also shrink the land area of Bangladesh.

It is predicted that the surface temperature of the earth could rise by about 1.8° to 6.3°C by 2100.

This could lead to a rise in sea levels by 0.5m and could threaten with inundation heavily

populated coastal and deltaic areas from Mississippi to Bangladesh. Climatic disasters such as

hurricanes, cyclones and droughts could become more frequent and severe. Tropical diseases

such as Malaria and Cholera may move north and south of the equatorial region due to global

warming.

To sum up, for Bangladesh, the climate changes caused by global warming may lead to more

rainfall, massive floods, great cyclones and droughts. However, conservation of the environment

and sustainable development strategies will definitely protect the earth and its environment and

will particularly save countries like Bangladesh from the catastrophe which can be induced by

global warming.

We have always stood up on our own feet, but sometimes it takes time and that slows down our

growth. In a competitive world, we cannot afford to remain behind and hence we have to factor

these calamities and restoration costs into our growth plan. The country has to project its GDP

considering such spending for major reconstruction work since this will come back again and

again and we have to face it realistically and united.

Reference

http://en.wikipedia.org/wiki/Cyclone_Aila

http://en.wikipedia.org/wiki/Cyclone_Akash

http://en.wikipedia.org/wiki/Cyclone_Bijli

http://en.wikipedia.org/wiki/List_of_Bangladesh_tropical_cyclones

http://en.wikipedia.org/wiki/Floods_in_Bangladesh

http://www.hotathrandom.com/BD-Global-Warming.htm