Climate Change and the Bleak Future of My Hometown in Bangladesh

12 Jun

During my childhood, as soon as it turned dark outside, my father would become frantic and check whether all the windows and all the outlets to the outside world were closed. I could hear his voice from across the house shouting, “We cannot let any of the mosquitoes get inside! It takes only one bite to kill you!” Despite my father’s utmost effort to keep the mosquitoes out of our house, one of these sneaky little creatures would sometimes manage to get inside. What ensued then was my mother’s panic as she would cover me in insect-repellent creams.

To an American reader, everything I have described until now may seem unusual, but it was a very ordinary evening at any household in my hometown of Dhaka, Bangladesh. Deadly mosquito-borne diseases such as malaria and dengue are common in Dhaka so people live in constant fear of mosquitoes. My family, like any ordinary family, was just trying their best to stay alive.

The sky of Dhaka at evening.

I wish I could tell you that the situation has improved since then, but unfortunately, climate change will increase the spread of mosquito-borne diseases in Dhaka. Bangladesh is one of the countries most vulnerable to the effects of climate change both because of its geographical location and economic conditions (1). It is a low-lying, tropical country bound by the Bay of Bengal in the south, by Myanmar in the Southeast and by India in the North, East and West. A developing economy that is densely populated, its 158,570,535 citizens live in an area of 147,570 km2 (2). As a frame of reference, Bangladesh is approximately the size of Iowa, but has about half as many people as the entire United States.

Bangladesh’s capital, Dhaka, where I was born and raised, is the most crowded city in the world (3). The impending effects of climate change will surely exacerbate the occurrence of infectious disease and cause potentially significant public health challenges. Infectious diseases spread by mosquitoes, such as malaria and dengue, are endemic to the tropical Southeast Asian region. Dhaka’s poor infrastructure, such as a lack of drainage systems, waste disposal and the abundance of slums, create suitable habitats for mosquitoes and aggravate the effects of climate change on the spread of diseases (4).

Human-caused climate change is responsible for an increase in the global mean temperature, a phenomenon also known as global warming. When I was a child, every summer when I complained of the heat, my mother recalled the time right after I was born in the summer of 1998. She fondly reminisced about the tantrum I had thrown as a newborn in that sweltering hot weather and the trouble she had to endure to pacify me.

Later, my mother would come to find out that the temperature in 1998 was a record high at that time (5). To all my later complaints about the weather, she would say that the heat was nowhere as bad as that of the summer of 1998. However, as I got a little older, and especially during my teenage years, the summers became so unbearable that I never felt like stepping outside of the house. For the first time, I heard my mother say that every summer now reminded her of the summer of 1998 (5).

For the months of May through September, an increase of 1℃ has been observed from 1976-2008 (7). This increasing trend in temperature is causing seasonal patterns to change in Bangladesh (7). Normally, the Bengali calendar has 6 six seasons that last for two months each.

The seasons of Bangladesh in my memory have always changed in such a timely manner that it would make you wonder whether nature was following a clock. In my childhood, summers had sunny skies, an enjoyable warmth and the red hue of krishnachura flowers that brightened all of Dhaka. Summers used to be distinct from monsoon, which followed summer. The temperature used to drop during monsoon. However, nowadays summer and monsoon are converging into one season as monsoon starts earlier than before and the high temperatures of the summer prevail for a longer period of time.

The streets of Dhaka in the summer months lined with Krishnachura.

An increase in temperature generally facilitates the growth of the mosquito population. Warmer environments also speed up the maturity of the parasites they carry, which means that more mosquitoes also means a greater potential for disease transmission. Unfortunately, this increase in mean temperature favors both Anopheles mosquitoes, which transmit malaria, and Aedes aegypti, which transmit dengue fever (6).

Aedes Aegypti mosquito, the carrier of dengue fever.

Anopheles mosquito, the carrier of malaria.

 

 

 

 

 

Lab experiments show that at consistent temperatures of 32-35 ℃, the incubation period of Aedes aegypti mosquitoes is shortened by a full week from its incubation period of 12 days at 30 ℃ (7). As temperatures increase in Dhaka then, we can expect an increase in the incidence of mosquito-borne diseases as the incubation period of mosquitoes decrease. In addition, average temperatures during winter are expected to increase by 1.4 ℃ by 2030 (7). This changing weather pattern will shorten the length of the reproductive cycle of mosquitoes, thus increasing the rate of population growth (8). Mosquitoes are not only helped by the increase in temperature, but also by the increased amounts of rainfall in Dhaka, which experiences the tropical monsoon climate.

I have always had a love-hate relationship with monsoon. Even though the roads were muddy, and sometimes I was stuck inside the house all day during monsoon months, it was still a glorious time of the year. I was always excited about the loud rhythmic rattle of the rain and the clear green of leaves that you could see right after the rain stopped. But monsoon also meant knee-deep water that you sometimes had to wade through to get to school and being stuck in traffic for long hours because the rain water got into a car’s engine.

Life in Dhaka during the monsoon months.

The arrival of monsoon also evokes fear in the hearts of many because it is the season when the outbreaks of mosquito-borne diseases occur all over Dhaka. Analysis of rainfall from 1976-2008 showed an increasing trend in the amount of rainfall during monsoon (7). There has been a corresponding increase in outbreaks of dengue from June to August (2). Data recorded over 2008 and 2009 shows that the number of dengue cases increase from around 50 to above 800 following the arrival of the monsoon during the months of June to August.

This increasing amount of rainfall creates pools of stagnant water which become optimal breeding sites for mosquitoes. An increasing population of mosquitoes allows for a faster spread of diseases (8). The increasing amount of rainfall coupled with the increase in temperature will act together to increase the rates of mosquito-borne illnesses in Dhaka.

Monthly dengue cases averaged over 2000–2010, showing seasonal incidence (7). [Img: Sharmin et al. (4)]

Not only are the temperature and level of rainfall increasing, but the occurrences of weather extremes such as floods are also becoming more frequent. Bangladesh is located on a river delta plain fed by 230 rivers. In the north, the glaciers in the Himalayas are melting, while in the south, the sea levels of the Bay of Bengal are rising. Both the water from the melting glaciers and the rising sea levels make Bangladesh vulnerable to frequent flooding.

A severe flood occurs in Bangladesh every four to five years, but this frequency is expected to increase with further climate change (2). A study has found that if total precipitation increases by 5%, an increased 20% of area in Bangladesh is likely to be flooded. In the past, outbreaks of dengue fever have occurred during a flood. Flooding causes water congestion in Dhaka which creates breeding sites for mosquitoes, thus mosquito populations grow which leads to an outbreak of dengue. As frequencies of flood increase with climate change, incidences of dengue fever is also expected to increase (4).

Streets of Dhaka during a flood.

The overcrowding of Dhaka is also another factor that affects the spread of mosquito-related diseases. Being born and raised in Dhaka, I have always known Dhaka as overpopulated. While growing up, I was used to frequently being stuck at red lights for 15 minutes. Whenever we visited our family members who lived 20 minutes away, our rides never took less than an hour. However, lately, it is getting worse as the population in Dhaka has been exponentially increasing because of incoming “climate refugees.”

Climate change has affected the rural agriculture-based economy of Bangladesh as changes in temperature, level of precipitation, and seasonal patterns damage crop production. This adverse effect on agriculture has forced a migration the rural areas to Dhaka, the economic hub of the country. These “climate refugees” live in slums, which lack good sanitation systems, a safe drinking water supply, and proper cooking and health care facilities (9). These substandard living conditions create the perfect condition for the spread of mosquito-borne disease.

A shortage of reliable fresh, clean drinking water results in residents storing what water they have in containers such as drums and earthen jars. Unfortunately, these containers are not sealed, and so the Aedes aegypti mosquito lays its eggs in them, precipitating outbreaks of dengue in the city. As climate change continues to affect agriculture in rural areas more people will migrate to Dhaka. Without an improvement in both Dhaka’s infrastructure and the living conditions in these slums mosquitoes will have the ability to infect a greater number of people (4).

Stagnant water bodies are breeding sites for mosquitoes.

When I have trouble falling asleep at night, sometimes I wonder about the fate of Dhaka. Lying in my college dorm bed in Massachusetts, with not even a single mosquito in sight, I think about what will become of these mosquitoes in Dhaka. Could they wipe out the entire population of Dhaka in the next 20 years? Or are they going to mutate to become some super-mosquito creature which will take over the world?

Sometimes I have a dream, or rather a nightmare, that I am walking through the streets of Dhaka in a quarantine suit and everybody else is dressed similarly. In my dream, I cannot really recognize the faces of anyone because millions and millions of mosquitoes are buzzing in the air. You may say that my dream is too far-fetched, but how much better could the reality be?

-Bushra Tasneem (’20) is a Mathematics and Computer Science double major from Dhaka, Bangladesh. She enjoys reading poetry and taking walks in the woods in her free time. She originally wrote a version of this piece for ENG 119 Writing Roundtable This Overheating World.

Works Cited:

  1. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.; IPCC;New York, 2013; pp 28-62
  2. Dastagir, M.R.; Modeling recent climate change induced extreme events in Bangladesh: A Review; Weather and Climate Extremes. 2015, 7, 49-60.
  3. World Economic Forum. https://www.weforum.org/agenda/2017/05/these-are-the-world-s-most-crowded-cities/ (accessed April 13, 2018).
  4. Sharmin, S.; Viennet, E; Glass K.; Harley, D; The emergence of dengue in Bangladesh: epidemiology, challenges and future disease risk. Royal Society of Tropical Medicine and Hygiene. 2015, 109, 619-627.
  5. Stevens, W. Earth Temperature in 1998 Is Reported at Record High.The New York TImes, Dec 1998.
  6. Yi, H.; Devkota, B.R.; Yu, J.; Oh, K.; Kim, J.; Kim, H.; Effects of global warming on mosquitoes & mosquito-borne diseases and the new strategies for mosquito control. Entomological Research.2014, 44, 215-235.
  7. 7.Basak, J.K.; Titumir, R.A.M.; Dey, N.C.; Climate Change in Bangladesh: A Historical Analysis of Temperature and Rainfall Data. Journal of Environment. 2013, 2, 41-46.
  8. Bostan, N.; Javed, S.; Nabgha-e-Amen; Eqani, S. Tahir, F. Bokhari, H.; Dengue fever virus in Pakistan: effects of seasonal pattern and temperature change on distribution of vector and virus. Review of Medical Virology, 2017, 27.
  9. Molla N. A.;  Mollah K. A.; Ali G.; Fungladda W.; Shipin O.V.; Wongwit W;  Tomomi H; Quantifying disease burden among climate refugees using multidisciplinary approach: A case of Dhaka, Bangladesh. Urban Climate, 2014, 8, 126-137.  

2 Responses to “Climate Change and the Bleak Future of My Hometown in Bangladesh”

  1. Sharon Seelig June 12, 2018 at 9:38 am #

    Thank you, Bushra, for your very thoughtful, sobering, and well-documented account of how we have changed the world, and not for the better.

  2. Anne June 13, 2018 at 10:49 am #

    This has been an interesting read.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: