CLIMATE AFFLICTIONS | SYNTHESIS REPORT Bangladesh: Finding It Difficult to Keep Cool Iffat Mahmud, Wameq Raza, and Rafi Hossain 2021 Disclaimer This volume is a product of the staff of the International Bank for Reconstruction and Development/The World Bank. The findings, interpretations, and conclusions expressed in this paper do not necessarily reflect the views of the Executive Directors of The World Bank or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on the part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Copyright The material in this publication is copyrighted. Copying and/or transmitting portions or all of this work without permission may be a violation of applicable law. 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CLIMATE AFFLICTIONS | SYNTHESIS REPORT Bangladesh: Finding It Difficult to Keep Cool Iffat Mahmud, Wameq Raza, and Rafi Hossain iv | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL Contents Acknowledgments vii Key Pointers ix CHAPTER 1 Bangladesh’s Vulnerability to Climate Change and Variability 1 CHAPTER 2 Observed Changes: 1901 to 2019 3 CHAPTER 3 Temperature Trends: 1976 to 2019 5 3.1 Bangladesh 5 3.2 Dhaka 10 3.3 Chattogram 11 CHAPTER 4 Changes in Precipitation 13 CHAPTER 5 Changes in Relative Humidity 17 CHAPTER 6 The Heat Index 21 CHAPTER 7 Future Climate Change: Risks and Impacts 23 CHAPTER 8 Why Does Climate Change Matter for Human Health and Wellbeing? 25 8.1 Evidence from around the world 25 8.2 Pathways by which climate change can directly or indirectly affect health 26 CHAPTER 9 Conclusions 29 References 30 Notes 31 Contents | v LIST OF FIGURES Figure 1. Change in mean historical monthly temperature (in °C), 1901 and 2019 4 Figure 2. Change in mean historical monthly rainfall (in mm), 1901 and 2019 4 Figure 3. Weather station locations in Bangladesh 6 Figure 4. Annual mean temperature (in °C) in Bangladesh, 1976 to 2019 7 Figure 5. Bangladesh national monthly maximum temperature (in °C), 1976–2019 7 Figure 6. Bangladesh national monthly minimum temperature (in °C), 1976–2019 8 Figure 7. Average increase in maximum temperature (in °C) by Bangladesh region or zone, 1980 and 2019 9 Figure 8. Change in maximum temperature (in °C) for each Bangladesh region or zone between 1980 and 2019 9 Figure 9. Maximum monthly average temperature (in °C), Dhaka city, 1976 to 2019 10 Figure 10. Minimum monthly average temperature (in °C), Dhaka city, 1976 to 2019 11 Figure 11. Maximum monthly average temperature (in °C), Chattogram city, 1976 to 2019 12 Figure 12. Minimum monthly average temperature (in °C), Chattogram city, 1976 to 2019 12 Figure 13. Annual mean rainfall (in mm) for Bangladesh, 1976 to 2019 14 Figure 14. Rainfall patterns across Bangladesh (in mm), 1980 and 2019 14 Figure 15. Monthly average rainfall (in mm), Dhaka city, 1976 to 2019 15 Figure 16. Monthly average rainfall (in mm), Chattogram city, 1976 to 2019 15 Figure 17. Variations in relative humidity (percentage) across Bangladesh, 1980 and 2019 18 Figure 18. Humidity (percentage), Dhaka city, between 1976 and 2019 19 Figure 19. Humidity (percentage), Chattogram city, between 1976 and 2019 19 Figure 20. Heat index (in °C) for cities of Dhaka and Chattogram for each month between 1976 and 2019 22 vi | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL Figure 21. Projected change in monthly temperature compared to 1986–2005 24 Figure 22. Projected change in maximum five-day rainfall compared to 1986–2005 24 Figure 23. Pathways by which climate change affects human health 27 Acknowledgments The authors of the report are indebted to the Bangladesh Meteorological Department for sharing weather data, and particularly for the cooperation extended by Bazlur Rashid, Meteorologist. Gail Richardson, Practice Manager of Health, Nutrition and Population, South Asia Region of the World Bank, provided oversight for this report, and the authors deeply appreciate her consistent support and encouragement. The draft report was shared with the Climate Change and Health Promotion Unit (CCCHPU) and the Institute of Epidemiology and Disease Control Research (IEDCR) of the Ministry of Health and Family Welfare (MoHFW) of the Government of Bangladesh. The authors are thankful for their technical advice and collaboration. The authors express their gratitude to the peer reviewers, Anna Koziel (Senior Health Specialist), Stephen Geoffrey Dorey (Health Specialist) and Muthukumara Mani (Lead Economist), as well as Dhushyanth Raju (Lead Economist), Shiyong Wang (Senior Health Specialist), and Tamer Samah Rabie (Lead Health Specialist) for their valuable comments. The authors are grateful to Mercy Tembon, Country Director for Bangladesh and Bhutan, World Bank, who chaired an internal review meeting to seek expert input for the finalization of the report. The authors are grateful for the financial support mobilized by the Global Facility for Disaster Reduction and Recovery (GFDRR) Multi-Donor Trust Fund as well as the Health Sector Support Project Multi-Donor Trust Fund, which is cofinanced by the Embassy of the Kingdom of the Netherlands (EKN), the Foreign, Commonwealth and Development Office (FCDO) of the United Kingdom, Gavi, the Vaccine Alliance, Global Affairs Canada (GAC), and the Swedish Development Cooperation Agency (Sida). vii Key Pointers • In the last 44 years (between 1976 and 2019), Bangladesh has become hotter, with a 0.5°C increase in mean temperature. Trend analyses indicate that the maximum temperature generally continues to rise for all months, and the increment has been the largest from February to November. Between 1976 and 2019, the maximum temperature increase in Dhaka was 0.5°C and in Chattogram 0.9°C. • Summers were hotter and longer in 2019 compared to 1901, with temperatures for March to October rising by 1.1°C to 1.3°C, except for July when it increased by 0.8°C. Winters are also becoming warmer, with the average temperature rising between 1.6°C and 1.9°C in November and December, and 0.6°C in January— calculated from annual data gathered from 1901 to 2019. With these changes, Bangladesh appears to be losing some of its distinct seasonal variations. • Bangladesh is one of the wettest countries of the world, with most areas receiving at least 1500 millimeters of rain, but it can experience as much as 5800 millimeters of rainfall per year. Rainfall and temperature have both become more erratic. • For the peak monsoon season, from June to August, average monthly mean rainfall has declined by 60 millimeters, except for July, when it declined by 1.34 millimeters. Mean monthly rainfall for September and October has increased by 43 millimeters, which indicates the monsoon period is becoming longer, extending now from February to October. Chattogram has experienced more rainfall than Dhaka in the last 44 years, on average. • Mean temperatures across Bangladesh are projected to increase 1.4°C by 2050 and 2.4°C by 2100. This warming is expected to be more pronounced in winter. Temperatures are generally increasing in the monsoon season of June to August. Rising temperatures that lead to more intense and unpredictable rainfall during the ix x | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL monsoon season and a higher probability of catastrophic cyclones, are expected to result in increased tidal inundation. • Annual rainfall will rise by 74 millimeters between 2040 and 2059. Cyclone-in- duced storm surges are likely to be exacerbated by a potential rise in sea level of more than 27 centimeters by 2050. • Bangladesh’s extreme vulnerability to the effects of climate change is well documented. Through a complex pathway, climatic conditions have already negatively impacted human health. This is likely to escalate if the predicted changes in weather patterns hold. • If global warming progresses toward a 4°C increase scenario—the worst-case scenario presented at the 2015 Paris Climate Change Conference of Practitioners— the deleterious effects on human physical and mental health, among other effects, are likely to escalate. 1 Bangladesh’s Vulnerability to Climate Change and Variability Bangladesh is a low-lying river delta with a long coastline of 711 kilometers and floodplains that occupy 80 percent of the country (Hasib and Chathoth 2016). The country experiences a multitude of natural disasters every year. Severe floods, cyclones, storms, tidal surges, and river erosion frequently cause loss of life, with devastating social and economic impacts. These extreme weather events are expected to be exacerbated by the effects of climate change (Rahman et al. 2019). The Government of Bangladesh’s National Climate Vulnerability Assessment identified a number of climate-related hazards in 2018 that are critical for Bangladesh, including increasing temperature and heat stress; more frequent and longer droughts; increasing rainfall intensity; higher river flows and flood risks; greater riverbank erosion; sea level rises and salinity intrusion; landslides; and increasing intensity of cyclones, storm surges, and coastal flooding (Government of Bangladesh 2018). In rural areas, where nearly 80 percent of the population live, climate change has an immediate and direct effect on the health and wellbeing of millions of people who depend on natural resources for their livelihoods. The impacts of climate change are also increasingly felt in large cities that are exposed to various climate-induced hazards, including variations in temperature, excessive and erratic rainfall, water logging, flooding, and heat and cold waves (Rabbani et al. 2011). These hazards are exacerbated by high population density, poverty, rural–urban migration, illiteracy, and a lack of public utilities and services (Rabbani et al. 2011). Rapid urbanization and a growing urban slum population are quickly changing the population dynamics in Bangladesh, and this has implications for climate-induced health risks (Mani and Wang 2014). The country has the world’s highest rate of mortalities that are caused by natural disasters, with more than half a million people lost to disaster events since 1970. The majority of these deaths have occurred during floods or cyclones (Nahar 2014). Not long ago, Bangladesh was hit by two major cyclones: Sidr in 2007 and Aila in 2009. Cyclone Sidr killed 3,406 people while more than 55,000 sustained physical injuries. Heavy rain and tidal waves caused by wind effects led to extensive physical destruction and damage to crops and livestock. After Cyclone Sidr, an assessment by the 1 2 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL Government of Bangladesh found widespread outbreaks of diarrhea, dysentery, acute respiratory infection, and pneumonia. Children ages five or younger were the most vulnerable (Kabir et al. 2016b). Cyclone Aila hit the southern coastline of Bangladesh and partly damaged the Sundarbans. Along with outbreaks of diarrheal diseases was an acute scarcity of drinking water and food (Kabir et al. 2016b). With the number and intensity of such storms or cyclones projected to increase (see chapter 7 for more details), climate change can reverse some of the significant gains Bangladesh has made in improving health-related outcomes, particularly in reducing child mortality, improving maternal health, and improving nutritional outcomes. 2 Observed Changes: 1901 to 2019 Rainfall and temperature variations have become more erratic in Bangladesh. A trend of significantly increasing cyclone frequency during November and May—the main months for cyclone activity in the Bay of Bengal—has been observed. This subsection focuses on changes in annual temperature and precipitation during the last 119 years. Bangladesh has a humid, warm climate influenced primarily by monsoon and partly by pre-monsoon and post-monsoon circulations. Average temperatures approximate 26.1°C but can vary between 15°C and 34°C throughout the year. The warmest months coincide with the rainy season—March to September—while the period from December to February receives less rainfall. Bangladesh is one of the wettest countries of the world, with most areas receiving at least 1500 millimeters of rainfall, but some areas as high as 5800 millimeters per year. Rainfall is driven by the Southwest monsoon, which originates over the Indian Ocean and carries warm, moist, unstable air beginning approximately in the first week of June and ending in the first week of October. Major climate drivers in Bangladesh, besides the Southwest monsoon, include the Easterly Trade Winds and the El Niño Southern Oscillation (ENSO). Overall, annual mean temperatures have risen in Bangladesh. Figure 1 shows the change in mean monthly temperature between 1901 and 2019, using averages for two 30-year periods: 1901–1930 and 1991–2019. Summers are hotter and longer, with average temperatures for March to October—based on annual data from 1901 to 2019—rising by 1.1°C–1.3°C, except for July when it increased by 0.8°C. Winters are also becoming warmer, with average annual temperature rising by 1.6°C–1.9°C in November and December, except for January when it increased by 0.6°C. The maximum change in annual temperature was in February, when it increased by almost 1.9°C. Figure 2 presents changes in mean monthly precipitation between 1901 and 2019, using averages for the same two 30-year periods: 1901–1930 and 1991–2019. For the peak monsoon season—June to August—average monthly mean rainfall declined by 60 millimeters, except for July when it declined by 1.34 millimeters. Mean monthly rainfall for September and October increased by 43 millimeters, which indicates that the monsoon period is becoming longer, now extending from February to October. 3 4 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 1. Change in mean historical monthly temperature (in °C), 1901 and 2019 2.0 1.9 1.8 1.6 Change (degrees Celsius) 1.5 1.3 1.3 1.2 1.1 1.1 1.1 1.0 0.9 0.8 0.6 0.5 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Source: Authors’ calculation based on data from the World Bank Climate Change Knowledge Portal and the Bangladesh Meteorological Department. The difference is based on two 30-year averages: 1901 to 1930 and 1991 to 2019. FIGURE 2. Change in mean historical monthly rainfall (in mm), 1901 and 2019 60 43.8 42.2 40 Change (millimeters) 20 0.6 0.9 –0.2 3.8 0 –1.1 –1.34 –20 –8.1 –40 –60 –46.5 –63.2 59.9 –80 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Source: Authors’ calculation based on data from the World Bank Climate Change Knowledge Portal and the Bangladesh Meteorological Department. The difference is based on two 30-year averages: 1901 to 1930 and 1991 to 2019. In the next three chapters, climate data for Bangladesh are analyzed for the period 1976 to 2019 based on data available from the Bangladesh Meteorological Department (BMD) to provide a more granular analysis of climate change in Bangladesh. For this purpose, data on minimum and maximum temperatures, rainfall, and relative humidity were collected from BMD. 3 Temperature Trends: 1976 to 2019 This chapter analyzes temperature changes recorded in Bangladesh between 1976 and 2019. Weather variables for Dhaka and Chattogram cities, the country’s two largest cities, are separately analyzed. Weather data were collected from BMD from 43 weather stations across the country. Figure 3 shows the distribution of these stations relative to population density. These 43 stations have been set up over time, which is why data for some of the earlier years, particularly between 1976 and 1990, are from fewer weather stations. 3.1 BANGLADESH Bangladesh has become warmer over the past 44 years (figure 4), with an increase in annual mean temperature of 0.5°C between 1980 and 2019, using three-year averages. The three-year average is based on the average annual maximum temperature for the years 1978–80 and 2017–19. This was done to counter potential one-off anomalies in weather patterns for any single year over the duration. As indicated by the trendline in figure 4, there has been a steep rise in mean temperature in the past 44 years and temperatures continue to rise. Figures 5 and 6 provide more detailed representation of changes in maximum and minimum temperatures between 1976 and 2019. Maximum temperatures show an increasing trend in all months, except December (figure 5). Between March and October, maximum temperatures were above 30°C and continue to rise. The green and yellow dots indicate maximum temperatures recorded in recent years. Figure 6 analyzes the change in minimum temperatures based on monthly averages over the period 1976 to 2019. Winter in Bangladesh officially occurs during the months of December and January. The trendlines in figure 6 indicate that the minimum temperature is rising in December, but has remained the same in January. According to the Bengali calendar year, Bangladesh has six seasons: grishsho or summer (April–May); borsha or monsoon (June–July); shorot or autumn (August– September); hemonto or late autumn (October–November); sheet or winter (December– January); and boshonto or spring (February–March). These seasons are normally marked 5 6 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 3. Weather station locations in Bangladesh Weather stations Population (millions) ≤ 1.500000 ≤ 2.580000 ≤ 3.960000 ≤ 8.440000 ≤ 13.140000 Temperature Trends: 1976 to 2019 | 7 FIGURE 4. Annual mean temperature (in °C) in Bangladesh, 1976 to 2019 28.0 27.6 27.5 27.5 27.5 27.3 27.3 27.3 27.2 27.2 27.2 27.2 27.227.1 27.0 27.1 27.0 27.0 27.0 27.0 26.9 26.9 26.9 26.9 26.9 26.9 26.9 26.8 26.8 26.8 26.7 26.8 Degrees Celsius 26.6 26.6 26.6 26.6 26.7 26.5 26.6 26.5 26.5 26.5 26.5 26.4 26.4 26.4 26.3 26.1 26.0 25.5 25.0 20 0 20 1 19 6 19 7 19 8 19 9 19 0 19 1 19 2 19 3 19 4 19 5 19 6 19 7 19 8 20 9 20 2 20 3 20 4 20 5 20 6 20 7 20 8 20 9 20 0 19 6 19 7 19 8 19 9 19 0 19 1 19 2 19 3 19 4 19 5 11 20 2 20 3 20 4 20 5 20 6 20 7 20 8 19 8 8 8 8 9 9 9 9 9 9 9 9 9 9 0 0 0 0 0 0 0 0 0 0 1 7 7 7 7 8 8 8 8 8 8 1 1 1 1 1 1 1 19 20 Note: The blue bars indicate year-specific mean temperatures; the orange line represents a linear trend. FIGURE 5. Bangladesh national monthly maximum temperature (in °C), 1976–2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 35 Maximum temperature (degrees Celsius) 30 25 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: Graph shows the monthly average maximum temperature for every year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve. 8 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 6. Bangladesh national monthly minimum temperature (in °C), 1976–2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 25 Minimum temperature (degrees Celsius) 20 15 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows the monthly average minimum temperature for every year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve. by distinct weather features. The analyses in this and subsequent chapters indicate these the distinctions among the seasons are getting blurred. Summers are becoming hotter and longer, now spanning from February to October, while the monsoon season is also spreading over a longer period—between March and October—with the peak monsoon season experiencing less rainfall. Additionally, winters are becoming warmer. In essence, Bangladesh appears to be losing its seasonality. Figure 7 presents further analysis of maximum temperatures by various regions or zones of Bangladesh, using three-year averages (that is, a comparison of the average annual maximum temperature for the years 1978–80 and 2017–19). This is done to counter potential one-off anomalies in weather patterns for any single year over the duration. In 1980, the western and central areas of Bangladesh experienced maximum temperatures in the range of 30.6°C to 31°C, while the southern part was in the range of 30.1°C to 30.5°C, and eastern areas the lowest—from 29.5°C to 30°C. This has changed dramatically over a 40-year period, and in 2019, the western part of the country recorded higher temperatures in the range of 31.6°C to 32°C; the central, southern, and southwest areas recorded 31.1°C to 31.5°C, while the northeastern part recorded the lowest of all regions—in the range of 30.6°C to 31°C. Figure 8 presents the incremental change in maximum temperature between 1980 and 2019 for these zones or regions, using three-year averages. While the western part of the country recorded the highest maximum temperature in 2019, incremental change in temperature over time was the highest for the eastern part of the country, at over 0.9°C. For the western region, the increase in maximum temperature was in the range of 0.6°C to 0.9°C; the increase was lowest for the central part—0.5°C or less. Temperature Trends: 1976 to 2019 | 9 FIGURE 7. Average increase in maximum temperature (in °C) by Bangladesh region or zone, 1980 and 2019 a. 1980 b. 2019 Note: Figures are based on three-year moving averages; that is, 1980 represents the average maximum temperature for the years 1978, 1979 and 1980; and 2019 represents the average for 2017, 2018 and 2019. This is done to counter potential one-off anomalies in weather patterns for any single year over the duration. The zones cover the following administrative divisions of Bangladesh—Central: Dhaka and Mymensingh; Northeast: Sylhet; Southeast: Chattogram; South: Barisal; Southwest: Khulna; and North: Rangpur and Rajshahi. FIGURE 8. Change in maximum temperature (in °C) for each Bangladesh region or zone between 1980 and 2019 Note: Figures are based on three-year moving averages; that is, 1980 represents the average maximum temperature for the years 1978, 1979 and 1980; and 2019 represents the average for 2017, 2018 and 2019. This is done to counter potential one-off anomalies in weather patterns for any single year over the duration. The zones cover the following administrative divisions of Bangladesh—Central: Dhaka and Mymensingh; Northeast: Sylhet; Southeast: Chattogram; South: Barisal; Southwest: Khulna; and North: Rangpur and Rajshahi. 10 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL 3.2 DHAKA Like the rest of the country, Dhaka is becoming warmer, with summers spanning a longer period. The maximum temperature has risen by 0.5°C over the last 44 years (figure 8), based on a comparison of three-year average for the years 1978–80 and 2017–19. This is done to counter potential one-off anomalies in weather patterns for any single year over the duration. Figure 9 presents monthly averages for maximum temperature for Dhaka between 1976 and 2019. In recent years (represented by the green and yellow dots in figure 9), the average monthly maximum temperature has risen above 32°C during March to October, with temperatures between April and June reaching close to or above 35°C. The minimum temperature in Dhaka is rising for all months (figure 10), which is quite different for the average for Bangladesh. As analyzed in section 3.1, for the national average, the minimum temperature has remained the same in January; for Dhaka, however, the trend shows a steep increase. FIGURE 9. Maximum monthly average temperature (in °C), Dhaka city, 1976 to 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 35 Maximum temperature (degrees Celsius) 30 25 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows the monthly average maximum temperature in Dhaka city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve. Temperature Trends: 1976 to 2019 | 11 FIGURE 10. Minimum monthly average temperature (in °C), Dhaka city, 1976 to 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 25 Minimum temperature (degrees Celsius) 20 15 10 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows the monthly average minimum temperature in Dhaka city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve. 3.3 CHATTOGRAM Although Chattogram has experienced an increase in temperature of 0.9°C over the last 44 years (figure 8), the maximum temperature shows a decreasing trend for all months (figure 11). This is very different from Dhaka as well as the national average for Bangladesh, where maximum temperatures are rising. Patterns of change in minimum temperature for Chattogram, presented in figure 12, show a rising trend for all months, similar to Dhaka. Minimum temperatures in December and January are still below 20°C. 12 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 11. Maximum monthly average temperature (in °C), Chattogram city, 1976 to 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 35 Maximum temperature (degrees Celsius) 30 25 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows the monthly average maximum temperature in Chattogram city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve, which is a trendline based on the scatterplot for each month. FIGURE 12. Minimum monthly average temperature (in °C), Chattogram city, 1976 to 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 25 Minimum temperature (degrees Celsius) 20 15 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows the monthly average minimum temperature in Chattogram city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve. 4 Changes in Precipitation In this subsection, precipitation data recorded by BMD between 1976 and 2019 are analyzed. Rainfall-related data are very location-specific and therefore using national averages for analysis is not the best possible option. Besides, there are 43 weather stations in Bangladesh that are not uniformly distributed across the country. In the absence of more reliable data, this generalized analysis is being used to estimate overall trends. Figure 13 shows changes in annual mean rainfall in Bangladesh for the years 1976 to 2019, using three-year averages for the years 1978–80 and 2017–19. This is done to counter potential one-off anomalies in weather patterns for any single year over the duration. The variation in rainfall across the years is quite substantial, ranging between 150 millimeters in 1992 and 250 millimeters in 2017, for example. This is why the trendline represented by the horizontal blue line (in figure 13) is relatively flat, indicating no major change. Figure 14 shows the variation in rainfall patterns in various parts of the country over the years 1980 and 2019, using three-year averages. Over time, the southern part of Bangladesh appears to have become drier, with average rainfall decreasing. In 1980, average rainfall recorded for the southwest and south was in the range of 150–200 millimeters, which declined to 129–150 millimeters in 2019. As mentioned above, this is a generalized analysis to document overall patterns in the absence of more localized information. Further analysis of rainfall data for Dhaka and Chattogram follow separately. Rainfall patterns for Dhaka and Chattogram are quite different, with Chattogram experiencing higher rainfall than Dhaka over the last 44 years (figures 15 and 16). Average rainfall for Dhaka is on the increase between the months of April and August, except in May when the overall trend indicates a decreasing pattern. Chattogram has had more rainfall than Dhaka in the last 44 years, on average. Average monthly rainfall in Chattogram for the months of June to August was close to 800 millimeters in recent years, and trends for June and July indicate that it may increase further. It should also be noted that rainfall data for Dhaka and Chattogram, as presented, are not very accurate because both of these divisions are geographically spread out over large areas, and one weather station each for Dhaka and Chattogram is insufficient. More localized information is required for more accurate analysis and predictions. 13 14 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 13. Annual mean rainfall (in mm) for Bangladesh, 1976 to 2019 300 250 200 Rainfall (millimeters) 150 100 50 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 00 00 00 00 00 00 00 00 00 01 01 01 01 01 01 01 01 01 01 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Note: The horizontal orange line represents the trend, while the vertical bars depict average rainfall in millimeters for the specific years indicated. FIGURE 14. Rainfall patterns across Bangladesh (in mm), 1980 and 2019 a. 1980 b. 2019 Note: Figures are based on three-year moving averages; that is, 1980 represents the average rainfall for the years 1978, 1979 and 1980; and 2019 represents the average for 2017, 2018 and 2019. This is done to counter potential one-off anomalies in weather patterns for any single year over the duration. The zones cover the following administrative divisions of Bangladesh – Central: Dhaka and Mymensingh; Northeast: Sylhet; Southeast: Chattogram; South: Barisal; Southwest: Khulna; and North: Rangpur and Rajshahi. Changes in Precipitation | 15 FIGURE 15. Monthly average rainfall (in mm), Dhaka city, 1976 to 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 800 600 Rainfall (millimeters) 400 200 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows the monthly average rainfall in Dhaka city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve FIGURE 16. Monthly average rainfall (in mm), Chattogram city, 1976 to 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1600 1400 1200 1000 Rainfall (millimeters) 800 600 400 200 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows trends in monthly average rainfall in Chattogram city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve. 5 Changes in Relative Humidity In this subsection, data on relative humidity (in percentage) recorded by BMD between 1976 and 2019 are analyzed. Like rainfall, humidity-related data are location-specific; using national averages for analysis is therefore not the best possible option. The 43 weather stations in Bangladesh are not uniformly distributed across the country. In the absence of more accurate data, this generalized analysis is being used to estimate overall trends. Figure 17 shows the relative humidity in various parts of the country and how it has changed between 1980 and 2019, using three-year averages. It appears that the North, Northeast and South of Bangladesh are becoming more humid over time; in 2019 the humidity levels were 80 percent or more in these regions. Humidity levels for Central Bangladesh (covering Dhaka and Mymensingh), Southwest (Khulna) and Southeast (Chattogram) remained unchanged over this period. 17 18 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 17. Variations in relative humidity (percentage) across Bangladesh, 1980 and 2019 a. 1980 b. 2019 Note: Figures are based on three-year moving averages; that is, 1980 represents the average humidity for the years 1978, 1979 and 1980; and 2019 represents the average for 2017, 2018 and 2019. The zones cover the following administrative divisions of Bangladesh – Central: Dhaka and Mymensingh; Northeast: Sylhet; Southeast: Chattogram; South: Barisal; Southwest: Khulna; and North: Rangpur and Rajshahi. The pattern of changes in humidity in Dhaka is significantly different from that in Chattogram. In Dhaka, average monthly humidity is declining (figure 18), while in Chattogram it is increasing during summer (figure 19), especially in June and July. Particularly in recent years (represented by the green and yellow dots in the scatter plots), humidity in the summer months in Dhaka has been falling and has been below 80 percent. In Chattogram city, however, humidity in recent years was close to or higher than 80 percent. Changes in Relative Humidity | 19 FIGURE 18. Humidity (percentage), Dhaka city, between 1976 and 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 80 Humidity (percentage) 60 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: the graph shows the monthly average humidity in Dhaka city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve (a trendline based on the scatterplot for each month). FIGURE 19. Humidity (percentage), Chattogram city, between 1976 and 2019 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Humidity (percentage) 80 60 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 1976 2019 Note: The graph shows the monthly average humidity recorded for Chattogram city for each year between 1976 and 2019. Trendlines across the years for each month (in red) are represented by a fitted Lowess Curve (a trendline based on the scatterplot for each month). 6 The Heat Index The change in the heat index for Dhaka and Chattogram, expressed in °C, is analyzed for the period 1976 to 2019 (figure 20). The heat index is a measure of the real-world feel when relative humidity is factored in along with the actual air temperature. The heat index was constructed using BMD’s data for maximum temperature and humidity to represent composite conditions, using the Rothfusz (1990) equation. Overall, the heat indexes reach danger levels during the months of April to October, with little variation over the years. A danger level of the heat index indicates that, with continued outdoor activity, heat cramps and heat exhaustion are likely, while heat stroke is probable. The major difference between Dhaka and Chattogram is noted in January, with Dhaka being relatively cooler than Chattogram. The greater number of green cells for Dhaka indicates that the heat is within normal limits of less than 27°C. A deeper look at the two indexes reveals differences over time; for example, in 1976 it was in the 40°C–45°C range for Dhaka and 40°C–47°C for Chattogram. But in 2018–2019, the range increased to 45°C–51°C for both cities. Heat waves and exposure to high temperatures negatively impact human health, with heat-related stress causing morbidity and mortality (Watts et al. 2020). Densely populated areas of the world are increasingly exposed to warmer climatic conditions and are experiencing higher changes in mean summer temperatures, compared to the global average (WMO 2020). Such extreme heat conditions are taking a toll on human health and overwhelming health systems, with greater consequences for places where extreme heat occurs in the context of aging populations, urbanization, urban heat island effects, and health inequalities (WMO 2020). The elderly, people with disabilities or preexisting medical conditions or both, and those exposed to heat from working outdoors or in uncooled environments are the worst affected by heat waves (Watts et al. 2020). Heat-related mortality among the elderly—people ages 65 years and over—has increased by 53.7 percent in the past 20 years (Watts et al. 2020). Due to heat stress, people’s productivity at work has declined: in Bangladesh an estimated 148 work hours per person was lost in 2019, which translates to 18.2 billion work hours lost in total for the country, compared to 13.3 billion work hours lost in 2013 (Watts et al. 2020). 21 22 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 20. Heat index (in °C) for cities of Dhaka and Chattogram for each month between 1976 and 2019 a. Dhaka b. Chattogram Month Month 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1976 27 31 40 38 45 42 42 41 44 41 36 27 1976 27 30 40 46 47 40 43 46 40 36 27 1977 25 31 43 42 41 42 44 43 47 38 33 27 1977 28 31 42 37 40 39 40 42 44 41 37 30 1978 25 28 35 44 43 44 44 44 43 44 35 29 1978 25 31 36 43 45 42 44 46 42 44 37 31 1979 28 28 38 47 54 46 44 45 44 42 37 26 1979 29 29 36 43 45 42 42 40 42 41 38 27 1980 25 29 38 51 44 45 42 43 43 39 34 28 1980 26 29 36 44 43 43 42 41 46 38 33 28 1981 26 28 35 38 43 47 42 47 45 41 34 26 1981 26 30 35 36 42 42 40 43 42 41 36 1982 28 29 35 43 50 45 46 42 46 43 31 27 1982 28 30 35 41 46 41 42 40 41 41 32 27 1983 25 28 38 43 45 50 46 43 44 41 35 27 1983 26 28 34 41 43 45 43 42 44 42 35 27 1984 25 29 42 48 43 42 43 43 43 43 34 28 1984 26 29 36 42 45 43 42 43 45 46 36 28 1985 28 31 46 47 45 45 42 45 45 44 36 31 1985 28 30 37 44 44 44 40 44 44 43 33 30 1986 28 31 43 47 49 51 46 49 43 42 35 30 1986 27 32 39 41 45 45 42 45 42 43 35 30 1987 28 34 38 47 52 52 45 45 46 44 36 30 1987 28 32 36 41 45 45 42 42 45 45 38 30 1988 29 35 41 53 49 46 47 45 49 46 37 30 1988 29 33 39 44 45 43 44 44 45 44 38 31 1989 26 31 41 52 52 48 46 47 47 43 36 28 1989 25 31 37 42 46 44 42 44 43 38 35 29 1990 26 29 33 42 42 46 44 46 46 37 36 28 1990 27 32 33 40 45 44 39 45 46 41 38 29 1991 25 31 40 48 45 45 46 45 42 41 31 25 1991 26 33 43 44 40 43 46 43 42 32 28 1992 24 26 39 56 47 50 44 44 45 43 34 27 1992 25 27 37 45 45 45 43 45 45 42 35 27 1993 25 32 35 43 42 44 43 42 44 43 35 29 1993 27 30 35 44 45 42 43 42 43 43 35 30 1994 28 28 40 44 48 44 44 44 46 45 36 30 1994 29 30 37 43 47 45 44 46 47 44 37 30 1995 26 30 40 52 53 48 45 47 47 47 36 29 1995 27 30 39 46 48 47 43 45 45 47 36 30 1996 27 33 46 49 53 47 49 45 53 44 37 29 1996 28 32 39 44 49 47 46 42 47 45 40 33 1997 25 29 41 39 48 46 45 48 45 43 37 26 1997 27 30 39 38 46 46 44 48 46 45 41 28 1998 23 31 35 44 48 53 46 45 48 49 39 32 1998 26 31 36 43 49 53 45 45 49 52 46 34 1999 29 36 43 53 46 47 44 44 44 44 37 29 1999 31 38 43 50 46 48 46 44 46 46 40 32 2000 25 26 35 44 44 45 43 44 44 41 35 28 2000 29 31 39 46 45 47 46 46 47 46 40 31 2001 25 31 37 46 43 42 43 46 45 43 34 27 2001 28 35 42 47 42 39 41 44 45 44 37 32 2002 26 30 36 41 44 45 45 43 45 40 33 27 2002 31 38 42 40 41 42 39 42 44 44 37 31 2003 22 30 34 47 47 43 45 45 44 42 33 27 2003 27 36 39 46 47 40 47 46 46 50 39 32 2004 24 30 39 43 49 46 43 44 41 39 33 29 2004 28 33 40 42 50 45 42 45 44 46 39 33 2005 25 31 40 46 46 49 43 45 48 39 33 29 2005 29 35 39 47 48 48 44 43 50 51 40 35 2006 26 37 38 44 47 46 46 45 44 43 34 28 2006 32 39 44 47 48 51 45 46 47 48 41 32 2007 25 29 34 45 49 46 44 46 44 42 34 27 2007 29 33 39 45 49 47 43 47 45 47 42 32 2008 25 31 38 45 49 46 45 45 47 41 34 27 2008 30 30 42 49 49 44 42 44 47 46 39 31 2009 27 31 38 50 50 51 46 47 47 42 34 27 2009 28 32 40 44 46 45 40 42 44 42 36 28 2010 24 30 42 50 48 48 47 48 46 43 35 27 2010 25 31 39 43 44 44 44 45 45 45 36 28 2011 24 30 36 42 48 47 45 42 45 43 34 25 2011 25 32 36 40 42 41 43 41 41 41 33 26 2012 24 29 39 45 49 47 46 45 47 42 32 24 2012 26 32 37 42 46 43 41 44 43 43 33 25 2013 24 30 39 44 43 48 45 44 47 42 34 28 2013 25 32 40 43 40 45 43 40 43 39 34 28 2014 25 28 36 47 50 48 46 46 46 42 35 25 2014 26 30 36 47 45 43 43 41 42 41 37 30 2015 25 30 35 42 47 46 44 46 46 43 35 27 2015 28 32 39 44 49 47 43 46 48 43 36 28 2016 25 33 39 52 47 49 46 47 48 45 35 30 2016 27 34 42 46 47 48 43 45 48 46 35 33 2017 27 31 35 43 50 48 45 48 49 44 35 29 2017 29 34 36 43 49 48 45 48 46 43 39 31 2018 24 32 40 43 45 51 48 50 51 41 35 27 2018 25 32 41 46 47 47 46 48 49 39 37 29 2019 28 30 36 45 50 49 49 50 49 44 2019 29 33 38 45 50 49 46 44 48 44 27-32°C Caution Fatigue is possible with prolonged exposure and activity. Continuing activity could result in heat cramps. 33-40°C Extreme caution Heat cramps and heat exhaustion are possible. Continuing activity could result in heat stroke. 41-54°C Danger Heat cramps and heat exhaustion are likely; heat stroke is probable with continued activity. Over 54°C Extreme danger Heat stroke is imminent. Note: The heat index is available at National Weather Service Weather Prediction Center (https://www.wpc.ncep.noaa.gov/html/heatindex.shtml). The light blue cells represent a “normal” temperature range” that does not adversely affect humans. 7 Future Climate Change: Risks and Impacts Using data from the World Bank Climate Change Knowledge Portal, this section discusses climate projections up to 2099 (World Bank n.d.). According to an assessment conducted by the Intergovernmental Panel on Climate Change (IPCC), continued emissions of greenhouse gases (GHGs) will cause further warming in Bangladesh (IPCC 2014). Mean temperatures across Bangladesh are projected to increase 1.4°C by 2050 and 2.4°C by 2100. This warming is expected to be more pronounced during the winter months, from December to February. Figure 21 presents the projected temperature changes for Bangladesh. The observed data indicate that the temperature is generally increasing in the monsoon season of June to August. Average monsoon season maximum and minimum temperatures show an increasing trend of 0.05°C and 0.03°C per year, respectively. Rising temperatures leading to more intense and unpredictable rainfalls during the monsoon season, and a higher probability of catastrophic cyclones, are expected to result in increased tidal inundation. This was evident during the 2020 super Cyclone Amphan, when Bangladesh experienced heavy monsoon rains that led to flooding in various parts of the country. More than a third of the country was flooded, and more than 4.9 million people were affected, with 42 fatalities. Figure 22 presents the projected change in maximum rainfall in Bangladesh. Peak five-day rainfall intensity—a substitute for an extreme storm event—is projected to increase. Annual precipitation will rise by 74 millimeters by 2040–2059. The frequency of tropical cyclones in the Bay of Bengal may increase, and according to the IPCC there is “evidence that the peak intensity may increase by 5% to 10% and precipitation rates may increase by 20% to 30%” (IPCC 2001). Cyclone-induced storm surges are likely to be exacerbated by a potential rise in sea level of more than 27 centimeters by 2050. 23 24 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL FIGURE 21. Projected change in monthly temperature compared to 1986–2005 a. 2020-2039 b. 2040-2059 c. 2060-2079 c. 2080-2099 Scale Monthly temperature (°C) -5 -4 -3 -2 -1 0 1 2 3 4 5 6 Source: World Bank n.d. Note: Future climate information is derived from 35 available global circulation models (GCMs) used in the IPCC 5th Assessment Report. Data are presented at a 1°x1° global grid spacing, produced through bilinear interpolation. FIGURE 22. Projected change in maximum five-day rainfall compared to 1986–2005 a. 2020-2039 b. 2040-2059 c. 2060-2079 d. 2080-2099 Scale Maximum five-day rainfall (millimeters) -60 -50 -40 -30 -20 -10 0 10 20 30 60 90 120 Source: World Bank n.d. Note: The maps are based on changes in the largest consecutive 5-day cumulative precipitation sum per month or year, relative to the reference period (1986–2005). These values are often larger during the warm season, and are broadly expected to increase because the atmosphere has a higher capacity to carry moisture as temperatures warm. 26 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL fever has risen by 9.5 percent globally since 1950, due to changing climatic conditions in dengue- endemic countries (Watts et al. 2018b). WHO and the United Nations Framework Convention on Climate Change (2015) have projected that mean annual temperatures will rise by 1.4–4.8°C over the period 1990–2100 in Bangladesh. By 2070, it is estimated, between 117 million and 147 million people will be at risk of malaria, depending on emission levels. The report states: “The health sector currently does not have adequate funding, infrastructure, human resource capacity, logistics and services required to fully address the impact of climate change on human health.” In 2008 the Bangladesh Ministry of Environment and Forests prepared Bangladesh Climate Change Strategy and Action Plan 2008, highlighting the need to implement surveillance systems for existing and new disease risks and to ensure that health systems are prepared to meet future demands. The strategy document states: “Climate change is likely to increase the incidence of water-borne and air-borne diseases. Bacteria, parasites, and disease vectors breed faster in warmer and wetter conditions and where there is poor drainage and sanitation” (Government of Bangladesh 2008). The combination of climate change and poverty is projected to affect between 35 million and 122 million people by 2030 (Balasubramanian 2018). If the average global temperature increases by 4°C—the worst-case scenario for global warming presented at the Paris Climate Change Conference of Parties in 2015—stresses on human health could overburden healthcare systems to a point where adaptation will no longer be possible (World Bank 2012). Hence, the urgency for the public sector to be better prepared to respond to the crisis. Although populations around the world are developing adaptive mechanisms such as public health strategies and improved surveillance to cope with the impacts, it is expected that the current levels of adaptation will be insufficient in the future (Watts et al. 2018a). 8.2 PATHWAYS BY WHICH CLIMATE CHANGE CAN DIRECTLY OR INDIRECTLY AFFECT HEALTH The effects of climate change on human health can be direct and indirect, immediate or delayed (McMichael 2012). The main pathways and categories of the health impacts of climate change are shown in figure 23. The direct or immediate effects include risks associated with increased frequency and intensity of heatwaves and extreme weather events such as floods, cyclones, storm surges, droughts, and altered air quality (McMichael 2012). The indirect effects occur through changes and disruptions to ecological and biophysical systems, which may result in altered food production, leading to undernutrition, water insecurity, air pollution, infectious diseases, mental health issues, and forced migration, with accompanying societal disruptions and further downstream effects (Patz et al. 2003; Takaro et al. 2013). Climatic conditions alter the epidemiology of infectious diseases. Despite an overall declining trend of infectious disease-related mortality around the world, it still accounts for 20 percent of the global burden of disease (Watts et al. 2018a). For instance, in 2016, deaths from dengue fever were the highest in the Southeast Asia region, which includes Bangladesh, and the overall trend is increasing, based on data gathered from 1990 to 2016. Furthermore, these climatic factors interact with behavioral, demographic, socioeconomic and other factors that influence the incidence, emergence, and distribution of such infectious diseases (Watts et al. 2018). Climate suitability for climate-sensitive infectious diseases has increased globally (Watts et al. 2020). Why Does Climate Change Matter for Human Health and Wellbeing? | 27 FIGURE 23. Pathways by which climate change affects human health Injuries, fatalities, Asthma, mental health impacts cardiovascular disease Severe Air weather pollution Malaria, dengue, Heat-related illness and deaths, encephalitis, hantavirus, cardiovascular failure Rift Valley fever, Lyme disease, ures chikungunya, West Nile virus erat Mo Extreme mp re Changes in te e heat vector ing xt rem ecology Ris e we 2 levels ather CO Environmental Increasing Ris g sin degredation allergens in a g re se Inc a le vel Forced migration, civil con ict, Respiratory mental health impacts allergies, asthma Water and food Water supply impacts quality impacts Cholera, Malnutrition, cryptosporidiosis, diarrheal disease campylobacter, leptospirosis, harmful algal blooms Source: World Bank Group and WHO (2018) Because of changes in temperature and rainfall patterns triggered by climate change, vectorial capacity is increasing for a number of climate-sensitive diseases. This increase in transmissibility is occurring along a wide range of temperatures and rainfall patterns. These are most acutely experienced in low- and middle-income countries (LMICs) (Watts et al. 2019). The number of cases of dengue fever, which is spread by mosquitoes, recorded annually has doubled every decade since 1990; one of the potential factors that has contributed to this increase is climate change (Watts et al. 2020). For malaria, another mosquito-borne disease, climate suitability has remained the same for the Southeast Asia region. Empirical evidence from Bangladesh shows, on average, that the likelihood of contracting an infectious disease is 19.7 percentage points lower in the dry season than during the monsoon. Humidity and mean temperature are negatively correlated with waterborne diseases but positively correlated with respiratory illnesses. One percent increase in relative humidity reduces the likelihood of contracting a waterborne disease by 1.6 percentage points, while an increase of 1°C in mean temperature reduces its 28 | BANGLADESH: FINDING IT DIFFICULT TO KEEP COOL likelihood by 4.2 percentage points. For respiratory illnesses, a one percent increase in humidity raises the likelihood by 1.5 percentage points, while an increase of 1°C in mean temperature raises it by 5.7 percentage points. For vector-borne diseases, an increase in temperature reduces the likelihood by 1.4 percentage points, although this is not statistically significant. 9 Conclusions Bangladesh’s vulnerability to the deteriorating effects of climate change is well documented. On account of its geographical attributes and location, Bangladesh is among the top-ten countries in the world most vulnerable to climate change. Evolving climatic conditions have already negatively impacted human health in the country, and the effects are expected to intensify with predicted changes in weather patterns. In tropical countries such as Bangladesh, infectious disease transmission is likely to precipitate certain vector-borne diseases such as malaria and dengue fever, and waterborne diseases such as diarrhea and cholera. Incidences of respiratory diseases can rise as a result of extreme temperatures that aggravate airborne allergens and pollution (World Bank 2012). A global rise in temperature of 4°C—by wide consensus regarded as the worst-case scenario of global warming2—would create unprecedented levels of stress on health that would likely overburden global health systems to a point where adaptation would no longer be feasible (World Bank 2012). The prevailing situation therefore underscores the urgency for the public sector to be better prepared to respond to the climate change crisis. Significant changes to the climate have already occurred in Bangladesh. Over the last 44 years, Bangladesh has become hotter, with a 0.5°C increase in mean temperature recorded between 1976 and 2019. Trend analyses indicate that maximum temperature continues to rise for all months except December, and that it has already substantially increased from February to November. Overall, summers are becoming hotter and longer, with the monsoon period now extending between February and October, while winters are becoming warmer. Bangladesh, in summary, appears to be losing its seasonal distinctions. The projected changes in climate will have significant ramifications on the health of several strata of the population. With further climatic changes predicted across Bangladesh—temperature is expected to rise approximately 1.4°C by about 2050, and annual rainfall to rise by 74 millimeters by 2040–2059—the deleterious effects on human physical and mental health are likely to escalate. 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NOTES 1 Climate projections are available from this portal. 2 This consensus was reached at the Paris Climate Change Conference of Parties in 2015, where the Paris Agreement was signed.