Climate Change and Health
Climate-related diseases are responsible for a large proportion of the global burden of disease. Human health is therefore not surprising predicted to be adversely affected by projected climate change.
Temperature rises and changes in rainfall patterns effect the prevalence of disease vectors such as malaria. Temperature increases decrease the larval development time resulting in an increase in the number of mosquitoes. This is concerning when the size of the vector population is proportional to the transmission of malaria. Land-use change also impacts transmission. Stagnant water, linked to increased irrigation or poor drainage, provides suitable habitats for mosquito breeding. In Uganda, a study found that cultivated swamp areas had higher temperatures than natural swamps, that explained increased local malaria transmission. Some assessments expect malaria transmission to decrease in large parts of the Western Sahel, but increase in southern and Eastern Africa, specifically in the highlands, that are currently malaria free. In Africa, there are currently 12.4 million cases of malaria a year, resulting in 155,000 – 310,00 deaths due to epidemics. As poverty increases from other factors, so disease incidence and prevalence is expected to grow further. Of particular concern is the co-infection of malaria and HIV.
Flooding is expected to increase with sea-level rise and the changing frequency of extreme events. When flooding occurs where sanitary infrastructure is inadequate, an increased frequency of epidemics and enteric diseases, such as cholera, typhoid, dysentery and mosquito-born diseases, can be expected. Heavy rain can also contaminate water supplies, moving soil-borne diseases such as anthrax and increasing contaminants such as heavy metals and organic chemicals. More frequent outbreaks of Rift Valley fever in East Africa could result from increased rainfall and a higher frequency of El Nino events.
Drought can directly affect health through dehydration, as well as compromising water quality. Lack of water also makes it difficult to keep clean, increasing risk of disease. The links between drought, crop production and malnutrition are probably most concerning, highlighting the links between climate, disease, food security and other stresses.
Increases in minimum temperatures may result in fewer dying of cold, but more people may die of heat stress in warmer weather. Higher levels of pollutants and increased deaths from respiratory diseases are expected from forest fires and increasing urbanisation. Meningococcal meningitis is associated with dryness, dust and very low humidity and transmission has been linked to wind speeds. Currently, 162 million people in Africa are exposed to this disease. Increased temperatures of coastal waters could aggravate cholera epidemics in coastal areas.
The short supply of health workers and poor health infrastructure in many African countries contributes to the challenge of managing growing health problems linked to climate change.
- AfricaAdapt Health Theme
- WHO factsheet on Climate Change and Health
- other WHO Publications on Climate Change and Health
- World Health Day 2008 – Key messages on Climate Change and Health
- World Health Day 2014 – Vector-Borne Diseases