Bangladesh - Climate

Bangladesh is one of the countries most vulnerable to climate change. Extreme weather events there have already been wreaking havoc on the people there. They're also causing a shift in migration and poverty patterns. Bangladesh is vulnerable to sea-level rise, like in the case of the Maldives, but other effects like drought, cyclone, lightning and river erosion have made this country more defenseless.

The Climate Change Vulnerability Index (CCVI-2011) calculated the vulnerability of 170 countries to the impacts of climate change over the next 30 years, which revealed that Bangladesh is the most vulnerable country to climate change. Maplecroft rates Bangladesh as the country most at risk due to extreme levels of poverty and a high dependency on agriculture, whilst its government has the lowest capacity of all countries to adapt to predicted changes in the climate. In addition, Bangladesh has a high risk of drought and the highest risk of flooding. This is illustrated during October 2010, when 500,000 people were driven from their homes by flood waters created by storms. However, despite the country’s plethora of problems, the Bangladesh economy grew 88% between 2000 and 2008 and was forecast to by the IMF to grow 5.4% over 2010 and up to 6.2% over the next five years.

In a new global index, Bangladesh has been ranked seventh among the countries most affected by extreme weather events in 20 years since 1998. The Long-Term Climate Risk Index listed Puerto Rico and Sri Lanka as the top two affected countries. The index is part of a report, Global Climate Risk Index 2019.

Bangladesh, one of the world’s most disaster-prone climate vulnerable countries, has faced dozens of major disasters over its short history as a nation. Located on the Bay of Bengal, Bangladesh is particularly susceptible to seasonal cyclones, acting as a funnel for heavy precipitation from the Indian Ocean and creating extreme weather events. The country sits on the flood plain of several major rivers, which drain from the mountainous regions of the Himalayas, making seasonal flooding another hazard often coinciding with the cyclone season. Current research and studies suggest that flood, tropical cyclones, storm surge and drought are likely to be more frequent and severe in the years to come.

Bangladesh is a highly climate vulnerable country whose emissions are less than 0.35% of global emissions. Without ambitious action to limit greenhouse gases internationally, the future costs of adapting to climate change will be much higher than they are today. If the world fails to take ambitious action, the costs to Bangladesh of climate change could amount to an annual loss of 2% of GDP by 2050 and 9.4% of GDP by 2100.

Bangladesh is already experiencing a host of climate impacts, including floods, storm surges, drought and river bank erosion. For example, floods in 2007 inundated 32,000 sq. km, leading to over 85,000 houses being destroyed and almost 1 million damaged, with approximately 1.2 million acres of crops destroyed or partially damaged, 649 deaths and estimated damage over $1 billion. Climate change will drastically hamper economic growth of the country.

In August 2017, 6.8 million people in northwestern Bangladesh found their land and crops drowned under flood water. The totally submerged land constituted over 16,000 hectares, while another 560,000 hectares of crops were partially damaged. That's not an isolated occurrence. In April the same year, floods wreaked havoc on Bangladeshi farmers, damaging around 220,000 hectares of ready-to-be harvested crops.

The main focus of Bangladesh’s activities is on increasing resilience to the impacts of climate change – which are already affecting the livelihoods of much of the population and will continue to do so in the future. For example, extreme temperatures, erratic rainfall, floods, drought, tropical cyclones, rising sea levels, tidal surges, salinity intrusion and ocean acidification are causing serious negative impacts on the lives and livelihoods of millions of people in Bangladesh, and are gradually offsetting the remarkable socio-economic development gained over the past 30 years, as well as jeopardising future economic growth.

Bangladesh is a Least Developed Country (LDC) whose emissions are less than 0.35% of global emissions. However, Bangladesh recognises that in order to meet the 2 degrees objective all countries will need to undertake mitigation in line with the IPCC conclusion that meeting 2 degrees requires global reductions to reduce by 40 to 70% global anthropogenic GHG emissions reductions by 2050 compared to 2010. Bangladesh’s approach is driven by the long-term goal announced by its Prime Minister that its per capita GHG emissions will not exceed the average for developing countries. Therefore, Bangladesh’s approach focuses on putting itself on a pathway which will avoid an increase of emissions per capita beyond this level, while pursuing national development goals.

Bangladesh has a subtropical monsoon climate characterized by wide seasonal variations in rainfall, moderately warm temperatures and high humidity. Regional climatic differences in this flat country are minor. Three seasons are generally recognized: a hot, humid summer from March to June; a cool, rainy monsoon season from June to October; and a cool, dry winter from October to March. In general, maximum summer temperatures range between 32°C and 38°C. April is the warmest month in most parts of the country. January is the coldest month, when the average temperature for most of the country is 10°C.

Winds are mostly from the north and northwest in the winter, blowing gently at one to three kilometers per hour in northern and central areas and three to six kilometers per hour near the coast. From March to May, violent thunderstorms, called northwesters by local English speakers, produce winds of up to sixty kilometers per hour. During the intense storms of the early summer and late monsoon season, southerly winds of more than 160 kilometers per hour cause waves to crest as high as 6 meters in the Bay of Bengal, which brings disastrous flooding to coastal areas.

Heavy rainfall is characteristic of Bangladesh. With the exception of the relatively dry western region of Rajshahi, where the annual rainfall is about 160 centimeters, most parts of the country receive at least 200 centimeters of rainfall per year. Because of its location just south of the foothills of the Himalayas, where monsoon winds turn west and northwest, the region of Sylhet in northeastern Bangladesh receives the greatest average precipitation.

From 1977 to 1986, annual rainfall in that region ranged between 328 and 478 centimeters per year. Average daily humidity ranged from March lows of between 45 and 71 percent to July highs of between 84 and 92 percent, based on readings taken at selected stations nationwide in 1986. About 80 percent of Bangladesh's rain falls during the monsoon season.

The monsoons result from the contrasts between low and high air pressure areas that result from differential heating of land and water. During the hot months of April and May hot air rises over the Indian subcontinent, creating low-pressure areas into which rush cooler, moisture-bearing winds from the Indian Ocean. This is the southwest monsoon, commencing in June and usually lasting through September. Dividing against the Indian landmass, the monsoon flows in two branches, one of which strikes western India. The other travels up the Bay of Bengal and over eastern India and Bangladesh, crossing the plain to the north and northeast before being turned to the west and northwest by the foothills of the Himalayas.

Natural calamities, such as floods, tropical cyclones, tornadoes, and tidal bores—destructive waves or floods caused by flood tides rushing up estuaries — ravage the country, particularly the coastal belt, almost every year. Between 1947 and 1988, thirteen severe cyclones hit Bangladesh, causing enormous loss of life and property. In May 1985, for example, a severe cyclonic storm packing 154 kilorneter-per-hour winds and waves 4 meters high swept into southeastern and southern Bangladesh, killing more than 11,000 persons, damaging more than 94,000 houses, killing some 135,000 head of livestock, and damaging nearly 400 kilometers of critically needed embankments. Annual monsoon flooding results in the loss of human life, damage to property and communication systems, and a shortage of drinking water, which leads to the spread of disease.

For example, in 1988 two-thirds of Bangladesh's sixty-four districts experienced extensive flood damage in the wake of unusually heavy rains that flooded the river systems. Millions were left homeless and without potable water. Half of Dhaka, including the runways at the Zia International Airport—an important transit point for disaster relief supplies—was flooded. About 2 million tons of crops were reported destroyed, and relief work was rendered even more challenging than usual because the flood made transportation of any kind exceedingly difficult.

There were few precautions against cyclones and tidal bores except giving advance warning and providing safe public buildings where people may take shelter. Adequate infrastructure and air transport facilities that would ease the sufferings of the affected people had not been established by the late 1980s. Efforts by the government under the Third Five-Year Plan (1985-90) were directed toward accurate and timely forecast capability through agrometeorology, marine meteorology, oceanography, hydrometeorology, and seismology.