Abdur Rahaman Rana
Weather and climate have affected human health for millennia. Climate change is altering weather and climate patterns that have previously been relatively stable. Over a longer time period, increased temperatures have other effects ranging from drought to ecosystem changes that can affect health. Droughts can result in shortages of clean water and may concentrate contaminants that negatively affect the chemistry of surface waters in some areas. Drought may also strain agricultural productivity and can result in increased food prices and food shortages, worsening strain on those affected by hunger and food insecurity. Ecosystem changes include migration of the vectors (organisms that do not cause disease but transmit infection by carrying pathogens from one host to another) and animal hosts that increase the prevalence of certain diseases. The dynamics of disease migration are complex and temperature is just one factor affecting the distribution of these diseases.
Winters will also be warmer, which is likely to lead to decreases in illness and death associated with exposure to cold, yet extreme weather and their direct health impacts, such as injuries and drowning from floods, will become more frequent. Indirect effects outnumber the direct effects and will likely be more costly. Potential indirect effects include aggravation of chronic diseases due to interruptions in health care service, significant mental health concerns both from interrupted care and relating to geographic displacement, and socioeconomic disruption resulting from population displacement and infrastructure loss. Sea level rise increases the risk from extreme weather events in coastal areas, threatening critical infrastructure and worsening immediate and chronic health effects. Salt-water entering freshwater drinking supplies is also a concern for these regions, and increased salt content in soil can hinder agricultural activity in coastal areas.
A comparative assessment of flood, drought and salinity prone areas in Bangladesh has produced results which show correlation coefficients between climate factors and health disorders, which varied among the study locations. Incidence of diarrhoea was found to have positive correlation with total annual rainfall in Rajshahi (drought prone) and Patuakhali (saline prone). Total monsoon rainfall was also found to have positively correlated with diarrhoea in Rajshahi (+0.21) and Patuakhali (+0.27). In contrast, dry seasonal rainfall was found to have a positive correlation with the study area.
The difference between annual maximum and minimum temperatures was found to be positively correlated with the incidence of diarrhoea in two study locations, Rajshahi and Patuakhali. However, the correlation was found to be negative in Sirajganj (flood prone).
A positive correlation implies that the incidence of diarrhoea increases as the variation of temperatures also increases. A negative correlation means a decrease in the incidence of diarrhoea when the temperature differential rises.
Skin diseases and malnutrition are also found to be positively correlated with temperature differentials in both Rajshahi and Patuakhali, while these are negatively correlated in the study area of Sirajganj (flood prone). The negative correlation of diarrhoea and skin diseases with temperature variation might have been due to non-climatic factors, as well as improved health services. The study shows that the households in Sirajganj have better access to safe water, sanitation and health services.
In spite of the apparent discrepancy in the correlation in time series data among three study locations, variation in temperature has been identified as a major cause of diarrhoea, skin disease and malnutrition in all the three locations.
The study also shows the climate-sensitivity of diarrhoea, skin disease and malnutrition as each of these diseases was found to have positively correlated with at least one of the climate variables. Moreover, skin disease and malnutrition are more or less highly (positively) correlated with all three climate variables (rainfall, temperature and salinity).
The study also reveals that poor and marginalised people of the areas monitored are suffering most, as they have no opportunity to access safe drinking water facilities, improved sanitation, hygiene facilities, or improved health facilities. The people who live below the poverty line make up the majority of the victims of climate induced diseases. Moreover, the burden of under privileged people in the study areas is increasing due to climate change and extreme events.
To overcome this worsening situation, safe drinking water supply, and improved sanitation and health facilities should be ensured for marginalised people in areas of Bangladesh prone to drought, flood and salinity.
Abdur Rahaman Rana is convener of the Bangladesh Youth Environment Safeguard (B-YES) – Outreach magazine
