Climate Change in Bangladesh and Disaster Risks
Bangladesh’s climate zones and its seasonal cycle for mean temperature and precipitation for the latest climatology, 1991-2020. Climate zone classifications are derived from the Köppen-Geiger climate classification system, which divides climates into five main climate groups divided based on seasonal precipitation and temperature patterns.
The five main groups are A (tropical), B (dry), C (temperate), D (continental), and E (polar). All climates except for those in the E group are assigned a seasonal precipitation sub-group (second letter). Climate classifications are identified by hovering your mouse over the legend. A narrative overview of Bangladesh’s country context and climate is provided following the visualizations.
Climatology / Climate Background of Bangladesh
Pre-monsoon, monsoon, and post-monsoon circulations influence the humid, warm climate of Bangladesh, which frequently encounters tropical cyclones and significant precipitation. The historical climate of Bangladesh has had annual temperatures that range from 150°C to 340°C, with an average of roughly 260°C.
The wet season (April-September) has the warmest months, whereas the winter season (December-February) is colder and dryer. With an annual average rainfall of 2,200 millimeters (mm), Bangladesh is a fairly rainy nation. Most places receive at least 1,500 mm of rainfall each year, and others, like the northeastern border regions, get as much as 5,000 mm.
The monsoon season sees the highest levels of humidity throughout the entire year (June to October). The Southwest monsoon, which rises over the Indian Ocean and transports warm, humid, and unstable air, is what causes rain to fall. Once every two to three years, a tropical cyclone (of strength classification Tropical Storm or higher) will make landfall in Bangladesh, bringing with it torrential rain, extremely high winds, and storm surges.
Climate Change in Bangladesh
Past, present, and future climate trends must always be understood in the context of the inherent variability. Here, the term “climate variability” refers to the ways in which some aspects of the climate, such as temperature and precipitation, “flicker” from year to year within their respective “ranges of variability”.
The connected atmosphere-ocean-land-ice system’s quasi-random internal variability may be the source of this natural variability (as weather variability is drawn out over many years). El Nio-Southern Oscillation-induced variability is a prime example of a cause falling within that category.
Other factors may include the influence of recurring natural disasters like violent volcanic eruptions that act as “forcing” events. “Internal climatic variability” is a summary of these external and internal natural forces. This internal climate variability is constant, albeit it can vary in intensity from time to time.
As a result, a climatology must be viewed as a mean with variability surrounding it. High latitudes are an example of an environment where variability can be very big from year to year, although it can also be minor in some places and for some variables (i.e., temperatures in the tropics).
A different forcing on the climate system than natural variability is imposed by anthropogenic releases of greenhouse gases and variations in air concentrations (such as CO2 and methane) along with changes in land surface and aerosol. In order to distinguish the effects of climate change from the inherent background variability, researchers look for signs. A regular trend over time or changes in the variability’s size can both indicate the presence of that signal.
Climate Change and Risk in Bangladesh
Based on the interaction of climate-related hazards (including dangerous events and trends), vulnerability of communities (susceptibility to harm and lack of capacity to adapt), and exposure of human and environmental systems, the overall risks from climate-related impacts are assessed. Hazards, exposure, and susceptibility are influenced by changes in the climatic system as well as socioeconomic processes, including adaptation and mitigation measures (IPCC Fifth Assessment Report, 2014).
This section gives an overview of the major natural disasters and the socioeconomic effects they have in a particular nation. Furthermore, it enables rapid assessment of the most vulnerable locations by spatially comparing data on natural hazards with data on development, thereby identifying sensitive livelihoods and natural systems.
Climate Change and Costal Risks in Bangladesh
Global mean sea level is directly rising as a result of the planet’s systematic warming in two main ways: (1) melting mountain glaciers and polar ice sheets are adding water to the ocean; and (2) as the oceans warm, the water expands, adding to the volume. Since 1880, the average sea level has increased by roughly 210–240 millimeters (mm), with the last two and a half decades accounting for almost a third of that increase. Currently, there is an annual rise of about 3mm.
Natural fluctuations in local winds and ocean currents, which can last for days, months, or even decades, are to blame for regional variances. Locally, however, other causes may also be significant, including ground uplift (such as the continuous recovery from Ice Age glacier weight), subsidence, changes in water levels brought on by water management practices or water extraction, and even the results of local erosive processes.
Sea level rise puts stress on coastal ecosystems as well as the actual coastline. Freshwater aquifers, many of which support municipal and agricultural water sources as well as natural ecosystems, can get contaminated by saltwater incursions.
Because there is a significant lag until an equilibrium is reached, sea level will keep rising as long as global temperatures continue to rise. Future carbon dioxide emissions and global warming will have a significant impact on the amount of the rise, while melting glaciers and ice sheets will likely have an increasing impact on the rate of the rise.
The analysis of historical sea surface temperatures, historical sea level anomalies (based on satellite observations), and projected future sea level rise on this page aids in the investigation of how our oceans are changing (model-based). Potential flood risk maps are shown in Projected Coastal Inundation due to Mean Sea Level Rise and Projected Coastal Inundation due to Mean Sea Level Rise + Storm Surge across scenarios and through the year 2150.
Recentclimate – Climate Change in Bangladesh