Increasingly variable rainfall patterns are likely to affect the supply of fresh water. A lack of safe water can compromise hygiene and increase the risk of diarrheal disease, which kills over 500 000 children aged under 5 years, every year. In extreme cases, water scarcity leads to drought and famine. By the late 21st century, climate change is likely to increase the frequency and intensity of drought at regional and global scale.

Floods and extreme precipitation are also increasing in frequency and intensity. Floods contaminate freshwater supplies, heighten the risk of water-borne diseases, and create breeding grounds for disease-carrying insects such as mosquitoes. They also cause drownings and physical injuries, damage homes and disrupt the supply of medical and health services.

In contrast, drought and chronic water shortages harm rural areas and 150 million city dwellers. If localities don’t adjust quickly, that number could be nearly a billion by 2050.

Rainfall pattern in Bangladesh

Spatial patterns of annual and seasonal rainfall trends of Bangladesh over the time period 1970–2017 has been assessed using rainfall data recorded at 35 stations distributed over the country. Historical dry and wet months are identified by using standardized precipitation index method and their trends are analyzed to assess the possible change in wet and dry events in Bangladesh. The result shows a significant increase in the average annual and pre-monsoon rainfall of Bangladesh. The number of wet months is found to increase and the dry months to decrease in most parts of the country. Seasonal analysis of wet and dry months shows a significant decrease of dry months in monsoon and pre-monsoon.