INTRODUCTION :

 

The warming of sea surface temperatures in the tropical Pacific causes changes in Pacific trade winds and ocean currents, setting off a chain reaction of weather disturbances worldwide. Scientists believe that Bangladesh is one of the most vulnerable countries in the world to El Niño or La Niña effects.[1] The country experienced very adverse El Niño effects in 1997-98, which included severe drought in various places and severe La Niña effects in 1998, which included the most devastating floods.  It is thought that the country was also affected by the 1972-73, 1976, 1982, 1986 and 1994 El Niño events.[2]   The country's geographical location and climatic characteristics made it vulnerable to such warm events.

 

The present study has been designed mainly to assess El Niño impacts and response strategies in Bangladesh and to depict the scientific views about their teleconnections.  Both primary and secondary sources of data and information have been used for the study. Relevant organizations like The Space Research and Remote Sensing Organisation (SPARRSO), the Bangladesh Meteorological Department (BMD), The Disaster Management Bureau (DMB), the Water and Power Development Authority (WAPDA), concerned experts, and governmental/non-governmental officials have been consulted. A seminar/workshop, comprising participants from concerned agencies and from various government departments and non-governmental organizations, was organized to incorporate a multi-dimensional approach to the study.

 

The present report has been divided into five sections. Section-I deals with El Niño/La Niña impacts in relation to the country's geophysical & socio-economic settings, the existing government mechanisms for dealing with the impacts of climate-related disasters, and the country's level of scientific research on and historical interest in El Niño. The flow of meteorological information about the 1997-98 El Niño event, including the transmission of El Niño information, media coverage, etc., has been depicted in Section-II. El Niño teleconnections to various parts of the country area have been scientifically analyzed and explained in Section-III. Section-IV deals with the forecasting by analogy of El Niño/La Niña impacts.  Section-V includes policy implications, recommendations and conclusions.

 

1.1   GEOPHYSICAL AND SOCIOECONOMIC SETTING

 

El Niño (or La Niña) events do not affect all regions of the world with same intensity. The vulnerability to El Niño effects depends upon the geographical setting, whereas the intensity of impacts of the events depends upon both the geographical and the socio-economic setting of a country.

 

 

 

1.1.1   Geophysical Features

 

Bangladesh is a transition zone between Southwest and Southeast Asia. It forms the capstone of the arch formed by the Bay of Bengal, and because of the Tibetan plateau (massif) to the north, it is a comparatively narrow land bridge between the sub-continent of India and sub-continent of Southeast Asia. More precisely, the country stretches latitudinally between 20° 34' N and 26° 33' N and longitudinally between 88° 01' E and 92° 41' E (Map 1). Some of the biggest rivers of the world flow through the country and form the largest delta in the world. The Ganges-Brahmaputra River system forms in the Bengal Basin, a delta of 40,225 sq. km. in extent. It is, therefore, quite obvious that the monsoon rains, the rise and fall of river levels, floods, alluvia and dilluvia and changes in river courses form the substance of both the cultural and physical geography of the area.

 

Geological studies suggest that, due to continental drifts and plate tectonic movements, the Gondwana part of the single continental mass Pangaea[3] underwent several changes through the processes of subduction, collision and sea-floor spreading. In the Oligocene Period (38 to 26 million years ago), some time after the plates collided, a portion of the northern part of the Indian plate fractured and sank below sea level. This portion was gradually filled up to form the eastern part of the Bengal Basin (Map 2).[4] Bangladesh is, therefore, formed on a mass of sediments washed down from the highlands on three sides of it, and especially from the Himalayas, where slopes are steeper and the rocks less consolidated.  The greater part of this land-building process must have been due to the Ganges and Brahmaputra Rivers. It is mainly a deltaic land having hundreds of big and small rivers, Haors (large lake-like bodies), Baors, Bils, etc., all over the country and some hills and mountains in the northeastern, eastern and southeastern parts of the country. The country has the longest continuous sea beach in the world (about 144 km).

 

Map-1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Source: Rashid, Harun Er.: Geography of Bangladesh. University Press Ltd., Dhaka, 1991, p.2.

                                                     

 

A vast amount of water (1073 million acre feet/year)[5] flows through Bangladesh of which 870 million acre feet/year flows into the country from India. This brings about 1.5 billion metric tons of sediments into the country every year.[6]   The climate of the country is characterized by high temperature, heavy rainfall, often-excessive humidity and a fairly marked seasonal variation (i.e., tropical climate). The country is very rich in bio-diversity.[7]   Due to its geographical location, landforms and a funnel-shaped seashore, Bangladesh is considered to be one of the most vulnerable disaster- prone countries of the world.

 

1.1.2     Socio-economic features

 

Bangladesh is an agrarian country with 120 million inhabitants within an area of 143,999 sq. km. of land. By religion, the country’s population consists of 86.6% Muslims, 12.1% Hindus and 1.3% Christians and other cultural minorities. Nearly four-fifths of the people depend, directly or indirectly, upon agriculture. The country's agro-based production system depends mainly on climatic phenomena. High population density, a rapid rate of population growth, low per-capita income (only $273 US a year), mass poverty, low literacy rate, high rate of unemployment, malnutrition (67% of the total population), weak economy, etc., are the major socio-economic features of the country.[8]

 

Many of the people of the country have some deep-rooted religious superstition regarding natural disasters. They believe that God imposes all disasters, especially climatic disasters as a result of our outrageous activities.[9]

 

 

Map-2

 

Source: Rashid, Harun Er: Geography of Bangladesh. University Press Ltd., Dhaka, 1991, p.8.

 

 

 

 

 

 

 

 

 

 

1.1.3     Government Mechanisms for Dealing with the Impacts of Climate-Related Disasters

 

To reduce the negative impacts of climate-related disasters and minimize the sufferings of the people, the Government has established a set of mechanisms including institutional arrangements for disaster preparedness and relief and rehabilitation of the area affected or potentially affected.  For making the established mechanisms appropriately and effectively operative, an exhaustive guidebook entitled, Standing Orders on Disaster, has been designed to outline the activities of each related ministry, division and major agencies and departments.  Considering the importance of the effects of climate-related disasters in Bangladesh, the government has also taken initiatives to formulate a comprehensive National Policy of Disaster Management and a National Disaster Management Plan. To deal with climate-related disasters by the entire government machinery, the National Disaster Management Council meets the requirement of clear policies and provides scope for proper implementation of the policy directives. A High Level Inter-Ministerial Disaster Management Coordination Committee gives decisions for implementation of these policies and policy directives. The Committee incorporates the role of the Ministry of Disaster Management and Relief as the responsible line Ministry, provides for integration of the Armed Forces and reflects the crucial role of Disaster Management Committees at Union, Thana and District levels. The Bangladesh Cyclone Preparedness Program (CPP) has about 30,000 volunteers to come to the rescue of the affected people in the coastal areas during cyclones.

 

The Bangladesh Space Research and Remote Sensing Organization (SPARRSO) and the Bangladesh Meteorological Department (BMD) are responsible for providing forecast information about climate-related disasters in the country.  The Bangladesh Water Development Board (BWDB) is responsible for forecasting water-related disasters like floods and their possible impacts.[10]   These organizations are also responsible for conducting research about climate-related disasters and their effects on society and environment.

 

The government media, Radio Bangladesh and Bangladesh Television, play the prime role in transmitting the forecast information, tracking the courses and chalking out elaborate programs on awareness development about preparedness and the possible effects of potential disasters. The National Dailies also play a vital role in these respects.

 

1.2        Climate-Related and Other Natural Hazards Affecting the Country

 

During the 1997-98 El Niño event, climate anomalies with significant socio-economic impacts were experienced outside the tropical Pacific. El Niño-related natural disasters are of global concern, have their most severe impacts on vulnerable communities, and can contribute to increasing poverty.[11]

 

Bangladesh is perhaps the only country in the world where casualties due to a cyclone could rise into the hundreds of thousands. Floods can devastate more than half the country causing damage in the billions of dollars. Nor'westers and tornadoes often demolish the economy and settlements in many parts of the country. Droughts destroy the country's food chain, food reserves and agro-based production systems. A large number of households become homeless as a result of riverbank erosion. Earthquakes cause severe damage to human settlements. The climate-related and other natural disasters affecting the country have been listed below in order of concern:

 

·       Floods

·       Tropical cyclones and associated storm and tidal surge

·       Nor'westers and tornadoes

·       Erosion

·       Drought

·       Earthquakes

·       Siltation

·       Salinity

·       Desertification

 

Scientists have found a correlation between El Niño/La Niña events and the variability of climatic phenomena in Bangladesh.  They have suggested that further research needs to be undertaken in this respect.

 

1.3        Level of Scientific Research on El Niño

 

El Niño (or La Niña) has drawn worldwide attention very recently. The world’s experts have differences of opinions regarding the origin and impacts of El Niño or (La Niña) events. Walker and Bliss (1932) believed that the periodic warming and cooling of the southern Pacific Ocean, which produces El Niño or La Niña effects, is actually related to a phenomenon known as Southern Oscillation. According to their view point, "when pressure is high in the Pacific Ocean, it tends to be low in the Indian Ocean from Africa to Australia; these conditions are associated with low temperatures in both these areas and rainfall varies in the opposite direction to pressure. Conditions are related differently in winter and summer, and it is therefore necessary to examine separately the seasons of December to February and June through August.”[12] The Southern Oscillation is a seesaw oscillation of pressure in the tropics between the Indian and the West Pacific Oceans on one hand and the Southeast Pacific Ocean on the other. This is an atmospheric phenomenon, whereas El Niño is an oceanic phenomenon.[13]   Bjerknes considered it to be an event of ocean-atmospheric coupling.[14]   An El Niño event is basically manifested by a reduction in coastal upwelling of cold, deep ocean water to the surface.  Some scientists have argued that this quasiperiodic appearance of warm surface water in the upwelling regions is triggered by various factors such as continental drift, tectonic movement of ocean plates, earthquakes or volcanic eruptions on the ocean’s bed. Greenhouse effects and global warming has also been interpreted as triggering factors of El Niño or La Niña event.[15] Some scientists explained it to be a combined effect of southeast trade winds, variations of sea surface temperatures (SSTs) and Coriolis Forces.[16]    Von Humboldt (in 1802) presented his Peru-Current Theory, which is popularly known as the Humboldt Theory, to explain the event. Klaus Wyrtki tried to explain the phenomena with his Equatorial Kelvin Wave Theory.[17]   Mark Cane stressed the importance of Rosby Wave Propagation from the eastern to the western Pacific.[18]   Numerical experiments are being carried out on a hierarchy of coupled models of the atmosphere and the ocean and encouraging results have been obtained toward El Niño predictions.

 

Many scientists had previously speculated that El Niño was caused by disturbances along the earth's crust, since earthquakes and volcanic eruptions often preceded the phenomenon.[19]   But new work with computer models and sophisticated monitoring equipment suggests that the current is not triggered by geological disruptions.  Instead, it is part of a naturally occurring cycle resulting in the interactions between the sea and the skies of the equatorial Pacific.  Scientists say that the latest monitoring efforts have helped them make more reliable El Niño predictions. Some scientists think that the decrease in tropical cyclone numbers frequency and intensity in recent decades might be interpreted as evidence that predictions of more and stronger cyclones accompanying warmer SSTs are wrong.[20]

 

Scientific research in Bangladesh relating to El Niño has not reached a satisfactory level. Research on the issue is mostly conducted on individual initiatives.  The researchers use data generated through both traditional and sophisticated methods by various national and international meteorological agencies.  In Bangladesh, studies have been conducted on "A Climatological Study of Bangladesh and the Possible Correlation with El Niño/Southern Oscillation" in 1993, "Bangladesh Floods, Cyclones and ENSO" in 1994, "Theory of El Niño" in 1994, "El Niño Southern Oscillation and Rainfall Variation Over Bangladesh" in 1996, "ENSO and Monsoon Rainfall Variation Over Bangladesh" in 1994, “El Niño and La Niña Cycle” in 1998 etc., with individual initiatives. SPARRSO took up a research project in 1999 entitled "Development of Models for Predicting Long Term Climate Variability and Consequent Crop Production as Affected by El Niño-La Niña Phenomena."   Besides, several studies have been conducted directly on the after effects of El Niño-La Niña phenomena.

 

Through these studies, scientists identified that the devastating flood of 1974 had occurred due to the 1972 El Niño event, and the severe floods of 1987 and 1988 had occurred because of the 1986 El Niño event. They had predicted during the 1997 El Niño event that a La Niña situation could develop after May 1998 and Bangladesh might experience severe flooding.[21] Scientific research found a negative correlation with tropical cyclones over the Bay of Bengal and a correlation of ENSO events with rainfall deficits over India and Bangladesh[22] during the 1951-87 period.

 

1.4        Historical Interests of El Niño before the Onset of the 1997-98 El Niño Event

 

There is no authentic historical record about when and how the first El Niño occurred, but geologists assume that El Niño began occurring since the Tertiary Period (2-65 million years ago).[23]   Recorded historical evidence proves that the first El Niño event occurred in 1925-26, although the term El Niño was not used in the record (except in association with impacts in Peru). The term El Niño came into worldwide use only recently. It is thought that El Niño has immense influences on monsoon climatic variability. Historical evidence shows that monsoon phenomena have been under study on this sub-continent since ancient times.  For example, monsoon phenomena have been mentioned in the holy Ramayana and Mohabharata and in other Vedic books. In the book Artha-Sastra (Science of Economics) written during the reign of Chandragupta Maurya (321-296 B. C.) by his Minister Kautilaya, there is mention about the amount of rains at different places, indicating that they had knowledge about rainfall measurements. The astronomer Varaha Mihir (505-587 A. D.) used to predict rains. Astronomer Arya Bhatta and Brahmagupta also studied the monsoon. The famous Sanskrit poet Kalidas composed poems out of monsoon clouds as depicted in his Meghdoot (Messenger of Cloud) and Ritusamahara (Cycle of Seasons). However, the real credit for the meteorological and agro-meteorological predictions during the ancient times goes to a mythical woman named Khana. Her verses are said to be the envy of any scientist at any time. Scientifically Gilbert Walker, during the time of British rule in India, identified effects of ENSO events in this Sub-continent.[24]   Sikka in 1980 was apparently the first to suggest that during El Niño years the Indian monsoon performs below normal. Parthasarathy and Pant observed in 1985 that the Indian monsoon shows a good correlation between a strong SOI (cold event) and a good monsoon year.[25]   Mandal conducted a study in 1989 on the relationship between tropical cyclones and rainfall over the Bay of Bengal and ENSO events. Chowdhury also conducted the same type of study in 1992. Ahmed in 1993 predicted that in general the Bangladesh monsoon shows a decrease in rainfall in El Niño years in all seasons.[26]

 

Today, experts opine that the ability to accurately predict the coming of El Niño could have a considerable impact on human development. After a scientific study, ERFEN (Estudio Regional del Fenómeno de El Niño) experts say, "By tracking ocean temperature, salinity levels and wind patterns, they can now tell when El Niño is approaching several months before it hits South America.”  National Center for Atmospheric Research (NCAR) Senior Scientist Michael Glantz says, "If you can forecast El Niño, you can shed light on when to expect droughts and floods in various countries."[27]     Khana, Ghagh, Varaha Mihir, Ahamika Duck, and Bhandori, etc., the most famous mythical persons in this sub-continent, told of these conditions 3-14 centuries ago.  They did not utter the words El Niño or La Niña in their sayings, but they rightly predicted the phenomena.[28]   Khana's sayings are especially considered to be the most important, most scientific and most talked about mythical worlds in Bangladesh and also in this region. Some of her sayings have been quoted and analyzed as follows:

 

Basically, Khana's sayings are based on astronomical readings. She did not correlate her forecasts to events like El Niño or La Niña episodes. Most of her meteorological readings seem to be very much based on local weather. But today's scientists found strong correlations between El Niño and La Niña episodes and local climatic behavioral patterns.[29]   What she told many centuries ago during the 9th lunar day of the bright fortnight in the Bengali month of Ashar (June-July), “If the month of Choitra (March-April) of a year experiences cold weather and the month of Baishakh (April-May) is marked by storms and hailstorms and the sky remains free from clouds, the year will receive sufficient rains; if rainfall is torrential, the year may experience drought; if rainfall is intermittent, the year may experience heavy flooding; if moderate rainfall occurs, crops will grow in abundance and if the sky remains clear and bright during sunset on that day, the year will experience salvation." Today's experts have found scientific bases behind these predictions. She also predicted that:

 

If southwest monsoon winds blow at the beginning of the year, the year will be marked by sufficient rainfall.

 

It means that when the southwest wind blows from the Bay of Bengal, it carries a lot of moisture and, as a result, plenty of rainfall occurs in summer (the beginning of the year). Khana also predicted these climatic phenomena in another way.  Khana's predictions about drought were the following:

 

If southern winds blow during rains, the rain will stop and flood will decrease.

 

Bhandori, another mythical person of this sub-continent predicted as follows:  “If Southwest winds blow for seven days continuously, the country will experience severe drought.” But Khana's forecasts directly about drought were as follows:

 

If the sky remains cloudy during the day and clear at night, the country will experience drought.

 

If hot weather in the month of Poush (December-January) and cold weather in the month of Baishakh (April-May) prevail and heavy rainfall occurs at the beginning of the month of Ashar (June-July), the months Shraban-Bhadra (July-September) will experience drought in that year.

 

Khana had very peculiar insights about the duration of rainfall in different seasons of the year. According to her:

 

If it is foggy during the month of Poush (December-January), there will be rain in the month of Baishakh (April-May) for the days exactly corresponding to the number of foggy days in Poush; if rain begins on Saturday, it will continue up to seven days; if it begins on Tuesday, it will continue up to three days.

 

Varaha Mihir also predicted these climatic phenomena in a different way: “If the month of Poush (December-January) does not experience excessive cold weather, the year will receive sufficient rains.”  According to Khana, "by observing the weather of the month of Poush (December-January), the weather of the whole year can be predicted. The weather condition of the first two and a half days of the month of Poush (December-January) is the indicator of every month of the next year.” She had devised a process of predicting a weather calendar, which, today, is considered to be very much scientific in nature.[30]

 

Some other predictions of Khana about floods, rains and agricultural production were as follows:

If Northern wind blows during the month of Shraban (July-August), the year will experience severe floods.

 

If rain occurs in the month of Choitra (March-April) and cold weather prevails in the month of Baishakh (April-May) in a year, scarce rainfall will occur in the new year.

 

The more the mangoes grow, the more the floods will occur; the more the jack-fruits grow in a year, the more the paddy will grow in that year.

 

It is true that the scientists on this sub-continent did not correlate the climatic phenomena to named events like El Niño or La Niña historically, but they predicted and recorded them.  These days, scientists are well-equipped with modern tools and technologies to predict future events and trace out the correlations of past events. It is remarkable that the great Bengal famine years of 1770, 1940-41, 1943 and 1974 were El Niño years.